Carrier Rtu Open 11 808 427 01 Users Manual

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RTU Open
Installation and Start-up Guide

CARRIER CORPORATION ©2010
A member of the United Technologies Corporation family · Stock symbol UTX · Catalog No. 11-808-427-01 · 11/19/2010

Table of Contents
Introduction .................................................................................................................................................................. 1
What is the RTU Open controller? ......................................................................................................................1
Specifications ........................................................................................................................................................3
Safety considerations...........................................................................................................................................4
Installation ................................................................................................................................................................... 5
Field-supplied hardware ......................................................................................................................................5
To mount the RTU Open.......................................................................................................................................6
To wire the controller for power..........................................................................................................................7
Using the rooftop equipment control power transformer ................................................................... 7
Using an auxiliary control power transformer ...................................................................................... 8
To set the RTU Open's address ...........................................................................................................................9
To set the RTU Open's communications protocol and baud rate............................................................... 10
Wiring the RTU Open to the MS/TP network ................................................................................................. 10
Wiring specifications ........................................................................................................................... 11
To wire the controller to the network ................................................................................................. 11
Wiring inputs and outputs ................................................................................................................................ 12
Input wiring specifications .................................................................................................................. 13
Inputs ................................................................................................................................................... 13
Binary outputs ..................................................................................................................................... 14
Analog output ...................................................................................................................................... 14
To wire inputs and outputs ................................................................................................................. 14
Wiring sensors to inputs ................................................................................................................................... 18
Field-supplied sensor hardware ......................................................................................................... 19
Wiring an SPT sensor .......................................................................................................................... 20
Rnet wiring specifications ........................................................................................................ 20
To wire the SPT sensor to the controller ................................................................................. 21
Wiring a Supply Air Temperature sensor ............................................................................................ 21
Wiring specifications ................................................................................................................ 22
To wire the SAT sensor to the controller ................................................................................. 22
Wiring a Duct Air Temperature sensor ............................................................................................... 22
Wiring specifications ................................................................................................................ 22
To wire a duct sensor to the controller ................................................................................... 23
Wiring an Outdoor Air Temperature sensor ....................................................................................... 23
Wiring specifications ................................................................................................................ 23
To wire an OAT sensor to the controller .................................................................................. 23
Wiring a CO2 sensor............................................................................................................................ 24
Wiring specifications ................................................................................................................ 24
To wire the CO2 sensor to the controller ................................................................................ 24
Wiring an Outdoor Air Quality sensor ................................................................................................. 25
Wiring specifications ................................................................................................................ 26
To wire the OAQ sensor to the controller ................................................................................ 26
Wiring a Relative Humidity sensor ..................................................................................................... 26
Wiring specifications ................................................................................................................ 27
To wire the RH sensor to the controller................................................................................... 27
Wiring a Humidistat ............................................................................................................................. 27
Wiring specifications ................................................................................................................ 27
To wire a humidistat to the controller ..................................................................................... 28
Wiring an enthalpy switch ................................................................................................................... 28
Wiring specifications ................................................................................................................ 28
To wire an enthalpy switch (outdoor air) to the controller ..................................................... 29
To wire an enthalpy switch (differential) to the controller...................................................... 30
RTU Open

Table of Contents

Wiring a status switch ......................................................................................................................... 31
Wiring specifications ................................................................................................................ 31
To wire a status switch to the controller ................................................................................. 32
Wiring a compressor safety ................................................................................................................ 32
Wiring specifications ................................................................................................................ 32
To wire a compressor safety input to the controller ............................................................... 33
Wiring an occupancy switch or door contact ..................................................................................... 33
Wiring specifications ................................................................................................................ 33
To wire an occupancy switch or door contact ......................................................................... 34
Start-up ....................................................................................................................................................................... 35
Service Test......................................................................................................................................................... 36
Configuring the RTU Open's properties .......................................................................................................... 37
Unit Configuration properties ............................................................................................................. 37
Setpoint properties.............................................................................................................................. 39
Service Configuration properties ........................................................................................................ 40
Sequence of Operation ............................................................................................................................................. 42
Occupancy........................................................................................................................................................... 42
Supply fan ........................................................................................................................................................... 43
Cooling ................................................................................................................................................................. 43
Economizer ......................................................................................................................................................... 44
Power Exhaust.................................................................................................................................................... 44
Unoccupied Free Cooling .................................................................................................................................. 45
Optimal Start ...................................................................................................................................................... 45
Enthalpy control ................................................................................................................................................. 46
Indoor Air CO2 .................................................................................................................................................... 46
Heating ................................................................................................................................................................ 47
Heat Pump operation ........................................................................................................................................ 48
Dehumidification ............................................................................................................................................... 48
Demand Limit..................................................................................................................................................... 49
Door switch ......................................................................................................................................................... 49
Remote occupancy ............................................................................................................................................ 49
Fire Shutdown .................................................................................................................................................... 49
Compressor Safety ............................................................................................................................................ 49
Fan Status ........................................................................................................................................................... 50
Filter Status ........................................................................................................................................................ 50
Alarms ................................................................................................................................................................. 50
Linkage ................................................................................................................................................................ 53
Linkage Air Source Modes................................................................................................................................ 54
Troubleshooting ......................................................................................................................................................... 55
Serial number ..................................................................................................................................................... 55
LED's .................................................................................................................................................................... 55
Replacing the RTU Open's battery .................................................................................................................. 56
Compliance ................................................................................................................................................................ 57
FCC Compliance ................................................................................................................................................. 57
CE Compliance ................................................................................................................................................... 57
BACnet Compliance........................................................................................................................................... 57
Appendix A: RTU Open Points/Properties .............................................................................................................. 58
Status................................................................................................................................................................... 58
Unit Configuration .............................................................................................................................................. 59
Setpoints ............................................................................................................................................................. 61
Alarm Configuration .......................................................................................................................................... 65
Service Configuration ........................................................................................................................................ 66
Maintenance ....................................................................................................................................................... 68
Alarms ................................................................................................................................................................. 70

RTU Open

Table of Contents

Linkage ................................................................................................................................................................ 71
I/O Points ............................................................................................................................................................ 71
Appendix B: Single Point Linkage and Device Address Binding ............................................................................ 73
Single Point Linkage ......................................................................................................................................... 73
Device Address Binding .................................................................................................................................... 74
Index ........................................................................................................................................................................... 75

RTU Open

iii

Introduction
What is the RTU Open controller?
The RTU Open controller is available as an integrated component of a Carrier rooftop unit, or as a fieldinstalled retrofit product. Its internal application programming provides optimum rooftop performance and
energy efficiency. RTU Open enables the unit to run in 100% stand-alone control mode or it can communicate
to the Building Automation System (BAS).
On board DIP switches allow you to select the baud rate and choose one of the following protocols:
•

BACnet

•

Modbus

•

Johnson N2

•

LonWorks

Carrier’s diagnostic display tools such as BACview6 Handheld or Virtual BACview can be used with the RTU
Open controller via the J12 Access Port. See illustration on the following page.

RTU Open

Introduction

RTU Open

Specifications
RTU Open driver

drv_rtuopn_std

Power

24 Vac ±10%, 50–60 Hz
20 VA power consumption (26 VA with BACview attached)
26 Vdc (25 V min, 30 V max)
Single Class 2 source only, 100 VA or less

Access port J12

To connect a BACview6 Handheld, Virtual BACview, or Field Assistant

Rnet port J13

For SPT sensors and a BACview6 in any of the following combinations, wired
in a daisy-chain configuration:
•
•
•

1 SPT Plus or SPT Pro
1–4 SPT Standards
1–4 SPT Standards, and 1 SPT Plus or SPT Pro

Any of the above combinations, plus a BACview6, but no more than 6 devices
total
Comm Option port

For communication with the LonWorks Option Card.

Inputs

12 inputs:
Inputs 1 - 2:

4-20 mA only

Inputs 3, 5, 8, 9:

Binary, 24 Vac

Inputs 6 - 7:

Thermistor

Inputs 10 - 11:

Thermistor

Rnet sensor
Binary outputs

8 relay outputs, contacts rated at 3 A max @ 24 Vac
Configured normally open.

Analog output

1 analog output
AO1: 2 - 10 Vdc or 4-20 mA

Output resolution

10 bit D/A

Real-time clock

Battery-backed real-time clock keeps track of time in event of power failure

Battery

10-year Lithium CR2032 battery provides a minimum of 10,000 hours of
data retention during power outages

Protection

Incoming power and network connections are protected by non-replaceable
internal solid-state polyswitches that reset themselves when the condition
that causes a fault returns to normal. The power, network, and output
connections are also protected against voltage transient and surge events.

Status indicators

LED's indicate status of communications, running, errors, power, and digital
outputs

Environmental operating
range

-40 to 158°F (-40 to 70°C), 10–95% relative humidity, non-condensing
NOTE Controllers should be mounted in a protective enclosure.
Vibration during operation: all planes/directions, 1.5G @ 20–300 Hz
Shock during operation: all planes/directions, 5G peak, 11 ms
Shock during storage: all planes/directions, 100G peak, 11 ms

RTU Open

Introduction

Overall dimensions

A:
B:

6-1/2 in. (16.5 cm)
6-1/2 in. (16.5 cm)

Mounting dimensions

7 mounting holes in various positions

Panel depth

2-1/2 in. (6.4 cm)

Weight

11.2 oz (0.32 kg)

BACnet support

Conforms to the Advanced Application Controller (B-AAC) Standard Device
Profile as defined in ANSI/ASHRAE Standard 135-2004 (BACnet) Annex L

Listed by

UL-873, FCC Part 15-Subpart B-Class A, CE EN50082-1997

Safety considerations

Disconnect electrical power to the RTU Open before wiring it. Failure to follow this warning could cause
electrical shock, personal injury, or damage to the controller.

RTU Open

Installation
To install the RTU Open:
1

Mount the controller (page 6).

Wire the controller for power (page 7).
○

Using the rooftop equipment control power transformer (page 7).

○

Using an auxiliary control power transformer (page 8).

Set the controller's address (page 9).

Wire inputs and outputs (page 12).

Wire sensors to the controller (page 18).

Field-supplied hardware
An RTU Open retrofit installation may require the following field-supplied components:
•

wiring harness: Part #OPN-RTUHRN

•

transformer – 24 Vac, 20 VA minimum

•

wiring

Application-dependent components:

RTU Open

•

carbon dioxide sensors

•

damper/damper actuator

•

differential pressure switch

•

enthalpy switch

•

fan status switch

•

door switch

•

fan section door switch

•

relative humidity sensor

•

remote occupancy contact

•

smoke detector

•

temperature sensors

Installation

To mount the RTU Open

When you handle the RTU Open:
•

Do not contaminate the printed circuit board with fingerprints, moisture, or any foreign material.

•

Do not touch components or leads.

•

Handle the board by its edges.

•

Isolate from high voltage or electrostatic discharge.

•

Ensure that you are properly grounded.

When you mount the RTU Open:
•

Do not locate in an area that is exposed to moisture, vibration, dust, or foreign material.

•

Follow NEC and local electrical codes.

•

Do not obstruct access for unit maintenance.

•

Protect from impact or contact during unit maintenance.

We highly recommend that you mount the RTU Open in the unit control panel!

RTU Open

Screw the RTU Open into an enclosed panel using the mounting slots on the cover plate. Leave about 2 in. (5
cm) on each side of the controller for wiring.

To wire the controller for power
CAUTIONS
○

The RTU Open is powered by a Class 2 power source. Take appropriate isolation measures when
mounting it in a control panel where non-Class 2 circuits are present.

○

Do not power pilot relays from the same transformer that powers the RTU Open.

○

In most cases, the RTU Open will be powered from the control power transformer provided with the
rooftop equipment. If you must use a separate control power transformer, additional precautions
must be taken to ensure that the auxiliary transformer is in-phase with the rooftop equipment’s
control power transformer. See Using an auxiliary control power transformer (page 8).

Using the rooftop equipment control power transformer

RTU Open

Remove power from the 24 Vac transformer.

Remove connector assembly from RTU Open's J1 connector.

Installation

If the rooftop equipment has thermostat connection terminals, connect wiring harness J1 wire 1 to R,
and J1 wire 3 to C. Alternately, connect the control power transformer wires to J1 connector wires 1 (24
Vac) and 3 (Gnd).

Apply power to the rooftop equipment.

Measure the voltage at the RTU Open’s J1 terminals 1 and 3 to verify that the voltage is within the
operating range of 21.6–26.4 Vac.

Attach harness to RTU Open connector J1.
NOTE The harness and connector are keyed and must be oriented properly for correct installation.

Verify that the Power LED is on and the Run LED is blinking.

Using an auxiliary control power transformer
If you use a separate control power transformer, it is essential that the auxiliary transformer and the rooftop
transformer are in-phase. You must verify this prior to connecting the auxiliary transformer to the RTU Open.
Follow these steps:
1

Verify the available primary voltage at the rooftop equipment.

Remove power from the rooftop equipment and install the appropriate auxiliary transformer. Follow the
manufacturer’s installation instructions.

Ground one leg of the auxiliary transformer’s secondary wiring.

Apply power to the rooftop equipment. Measure the potential between the rooftop equipment control
power and auxiliary transformer's secondary hot (non-grounded) legs. If the voltage measured is less
than 5 volts, the transformers are in-phase; proceed to step 7. If you measure a voltage greater than 24
Vac, then the phases are reversed.

Correct the phase reversal by either of the following methods:
○

Remove the ground from the secondary at the auxiliary transformer and connect it to the other
secondary

○

Reverse the primary wiring at the auxiliary transformer

Repeat step 4 to rewire.

Remove connector assembly from RTU Open's J1 connector.

Connect the auxiliary transformer wires to J1 wires 1 (24 Vac) and 3 (Gnd).

Apply power to the transformer.

10 Measure the voltage at the RTU Open’s J1 - 1 and 3 to verify that the voltage is within the operating
range of 21.6–26.4 Vac.
11 Attach harness to RTU Open's connector J1. See illustration below.
NOTE The harness connectors are keyed and must be oriented properly for correct installation.
12 Verify that the Power LED is on and the Run LED is blinking.

RTU Open

Optional
*

Safety chain devices, field-installed - normally closed. Apply 24 Vac to this terminal
(jumper from J1 - 1 to J1 - 9) where no safety devices are installed.

Fire shutdown device, field-installed, configurable as normally open or closed

***

Enthalpy switch, field-installed - configurable as normally open or closed

To set the RTU Open's address
The RTU Open's two rotary switches determine the RTU Open's MAC address when it is placed on an MS/TP
network. The rotary switches define the MAC address portion of the RTU Open's BACnet device instance
number, which is composed of the MS/TP network number and the MAC address. They also set the slave
address on a Modbus or N2 network when less than 100. See the RTU Open Integration Guide for additional
information on integration.
CAUTION The MAC address of the controller must be unique on its network.

RTU Open

Installation

Turn off the RTU Open's power. The controller reads the address each time you apply power to it.

Using the rotary switches, set the MSB (SW1) (10's) switch to the tens digit of the address, and set the
LSB (SW2) (1's) switch to the ones digit.
EXAMPLE To set the RTU Open’s address to 01, point the arrow on the MSB (SW1) switch to 0 and the
arrow on the LSB (SW2) switch to 1.

Turn on the RTU Open's power.

NOTE The factory default setting is "00" and must be changed to successfully install your RTU Open.

To set the RTU Open's communications protocol and baud rate
RTU Open's SW3 DIP switches are used to set the controller's protocol and baud rate. The protocol and speed
selection is determined by the network on which the controller will be installed. For Carrier BACnet
implementations, select MS/TP @ 76.8 k as follows:
1

Power down the RTU Open. The controller reads the protocol and baud rate each time you apply power to
it.

Set SW3 DIP switches 1, 2, and 4 to On to configure the controller for BACnet MS/TP and 76.8 k baud.

Power up the RTU Open.

NOTE Other protocols and baud rates are available. See the RTU Open Integration Guide for additional
instructions.

Wiring the RTU Open to the MS/TP network
The RTU Open communicates using BACnet on an MS/TP network segment communications at 9600 bps,
19.2 kbps, 38.4 kbps, or 76.8 kbps.
Wire the controllers on an MS/TP network segment in a daisy-chain configuration.

RTU Open

Install a BT485 on the first and last controller on a network segment to add bias and prevent signal
distortions due to echoing.

See the MS/TP Networking and Wiring Installation Guide for more details.

Wiring specifications
Cable:

22 AWG or 24 AWG, low-capacitance, twisted, stranded, shielded copper wire

Maximum length:

2000 feet (610 meters)

To wire the controller to the network
1

Pull the screw terminal connector from the controller's power terminals labeled Gnd and 24 Vac or Hot.

Check the communications wiring for shorts and grounds.

Connect the communications wiring to the BACnet port’s screw terminals labeled Net +, Net -, and
Shield.
NOTE Use the same polarity throughout the network segment.

Verify that the MSTP jumper is set to MSTP.

Set DIP switches 1 and 2 to the appropriate baud rate. See the MSTP baud diagram on the RTU Open.
The default baud rate is 76.8 kbps.
NOTE Use the same baud rate for all controllers on the network segment.

RTU Open

Insert the power screw terminal connector into the RTU Open's power terminals.

Verify communication with the network by viewing a module status report.

Installation

Wiring inputs and outputs
RTU Open Inputs and Outputs Table
Channel
Number

Type

Signal

Function

Part Number

Wire/Terminal
Numbers

Alternate
Terminals

Input 1

4-20 mA

CO2
OAQ
Space Relative Humidity

J4 - 5 & 6

N/A

Input 2

4-20 mA

CO2
OAQ
Space Relative Humidity

J4 - 2 & 3

N/A

Input 3

24 Vac

Compressor Safety **
Fan Status
Filter Status
Remote Occupancy
Door Contact

33ZCT55CO2
33ZCT56CO2
33ZCSENCO2 w/
33ZCASPCO2
33ZCSENSRH-01
33ZCT55CO2
33ZCT56CO2
33ZCSENCO2 w/
33ZCASPCO2
33ZCSENSRH-01
N/A
33CSAS-01
33CSFS=01
Field-supplied
Field-supplied

J1 - 2

J5 - 5 & 6

J1 - 9
J1 - 10

N/A

J2 - 1 & 2

N/A

J2 - 3 & 2

N/A

33SENTHSW
33CSAS-01
33CSFS-01
Field-supplied
Field-supplied
TSTATCCPLH01-B
33CSAS-01
33CSFS-01
Field-supplied
Field-supplied
33ZCT55SPT 33ZCT56SPT
33ZCT59SPT
33ZCT56SPT 33ZCT59SPT

J2 - 6 & 7

J5 - 1 & 2

J5 - 7 & 8

N/A

J20 - 1 & 2

N/A

J20 - 3 & 4

N/A

***

Input 4

24 Vac

Safety Chain *

N/A

Input 5

24 Vac

Input 6

Input 7

Field-supplied
33CSAS-01
33CSFS-01
Field-supplied
Field-supplied
33ZCSENSAT
33ZCSENDAT
33ZCSENOAT

Input 8

10K
Thermistor
10K
Thermistor
24 Vac

Fire Shutdown **
Fan Status
Filter Status
Remote Occupancy
Door Contact
Supply Air Temperature

Input 9

24 Vac

Input 10

10K
Thermistor

Input 11

100K
Thermistor

Rnet

Space Temperature
Setpoint Adjust
Zone Temperature

SPS / SPPL / SPP

J13 - 1, 2, 3, 4

N/A

AO - 1

Economizer

Actuator-Field-supplied

N/A

AO - 2

N/A

Not used

N/A

BO - 1

N/A - Relay

Fan (G)

N/A

BO - 2

N/A - Relay

Heat 2 (W2) Output

N/A

BO - 3

N/A - Relay

Heat 1 (W1) Output

N/A

BO - 4

N/A - Relay

Cool 2 (Y2) Output

N/A

BO - 5

N/A - Relay

Cool 1 (Y1) Output

N/A

J2 - 5 & 4
J22 - 1 & 2
J1 - 4
J1 - 5
J1 - 6
J1 - 7
J1 - 8

BO - 6

N/A - Relay

Humidi-MiZer™

N/A

BO - 7

N/A - Relay

Reversing Valve

N/A

J11 - 7 & 8
J11 - 4 & 6

Outside Air Temperature
Enthalpy **
Fan Status
Filter Status
Remote Occupancy
Door Contact
Humidistat **
Fan Status
Filter Status
Remote Occupancy
Door Contact
Space Temperature

J5 - 3 & 4
***

***

N/A
N/A
N/A
N/A
N/A
N/A
N/A

RTU Open

Channel
Number

Type

Signal

Function

Part Number

Wire/Terminal
Numbers

Alternate
Terminals

BO - 8

N/A - Relay

Power Exhaust

N/A

J11 - 1 & 3

N/A

Legend
AI - Analog Input

BI - Digital Input

AO - Analog Output
BO - Digital Output

* Safety Chain Feedback - 24 Vac required at this wire to provide Run Enabled status. Provide a jumper from J1 - 1 to J1 - 9 if no
safeties are utilized. See To wire inputs and outputs (page 14) for additional information on the RTU Open wiring harness assembly
terminations.
** Default input function
*** Parallel screw terminal at J5 (J5 - 1 = J2 - 6, J5 - 3 = J1 - 10, J5 - 5 = J1 - 2) may be used in place of the associated flying leads at
the harness (OPN-RTUHRN). See To wire inputs and outputs (page 14) for additional information.

Input wiring specifications
Input

Maximum length

Minimum gauge

Shielding

Thermistor

1000 feet
(305 meters)

22 AWG

Unshielded

4-20 mA

3000 feet
(914 meters)

22 AWG

Unshielded

1000 feet
(305 meters)

22 AWG

Unshielded

500 feet
(152 meters)

22 AWG
4 conductor

Unshielded

Binary input

SPT (RNET)

Inputs
These RTU Open inputs accept the following signal types:

RTU Open

These
inputs...

Support this
signal type...

1, 2

4-20 mA

The input resistance on the positive (+) terminal is 250 Ohms.
The Aux Power Out terminal is capable of supplying 24 Vdc to
a 4-20 mA transducer, but the total current demanded must
not exceed 40 mA. If the voltage measured from the Aux
Power Out terminal to Gnd is less than 18 Vdc, you need to
use an external power supply.

3, 5, 8, 9

Binary (24 Vac)

24 Vac voltage, resulting in a 25 mA maximum sense current
when the contacts are closed

6, 7, 10

Thermistor

10 kOhm at 77° F

100k Potentiometer

Typically used for 33CZT56SPT Setpoint Offset Potentiometer

Description

Installation

Binary outputs
The RTU Open has 8 binary outputs. You can connect each output to a maximum of 24 Vac/Vdc. Each output
is a dry contact rated at 3 A, 24 V maximum, and is normally open.
To size output wiring, consider the following:
•

Total loop distance from the power supply to the controller, and then to the controlled device
NOTE Include the total distance of actual wire. For 2-conductor wires, this is twice the cable length.

•

Acceptable voltage drop in the wire from the controller to the controlled device

•

Resistance (Ohms) of the chosen wire gauge

•

Maximum current (Amps) the controlled device requires to operate

Analog output
The RTU Open has 1 analog output that supports voltage or current devices. The controlled device must share
the same ground as the controller and have input impedance of 500 Ohms maximum for the 4-20 mA mode
on AO - 1.

To wire inputs and outputs
1

Turn off the RTU Open's power.

Connect the input wiring to the screw terminals on the RTU Open.

Turn on the RTU Open's power.

Set the appropriate jumpers on the RTU Open.

J3
W1
W2
W3
W4
W5
W6

AO - 1

0 - 10 Vdc/4-20 mA

Battery Jumper

In (Do not remove)

Format Jumper*

Out

Input 11 mA Jumper

Out (mA not utilized on this channel)

Input 11 Thermistor

In (default position)

Input 10 mA Jumper

Out (mA not utilized on this channel)

Input 10 Thermistor Jumper

In (default position)

*Formatting the controller may result in lost information and should only be done under the guidance of
Carrier Control Systems Support.

RTU Open

Optional
*

Safety chain devices, field-installed - normally closed. Apply 24 Vac to this terminal
(jumper from J1 - 1 to J1 - 9) where no safety devices are installed.

Fire shutdown device, field-installed, configurable as normally open or closed

***

Enthalpy switch, field-installed - configurable as normally open or closed

J4 Inputs
1

Turn off the RTU Open's power.

Connect the input and output wiring to the screw terminals on the RTU Open.

NOTE When utilizing the controller's 24 Vdc auxiliary power out, the total current demand for these two
input channels must not exceed 40 mA (100mA per channel).

RTU Open

Installation

NOTE J4 Analog Inputs 1 and 2 may be set for the following device types:
○

IAQ Sensor

○

OAQ Sensor

○

Space RH Sensor

J5 Inputs

The terminals for Inputs 3, 5, and 8 are available for use in place of the flying wire leads at Molex
connectors J1 and J2 identified below:

NOTE J5 binary inputs 3, 5, and 8 are the same input channels as:

○

J1 wire 2, J5 - Input - 3 (Compressor Safety)

○

J1 wire 10, J5 - Input - 5 (Fire Shutdown)

○

J2 wire 6, J5 - Input - 8 (Enthalpy Switch).

RTU Open

These terminals are available for use in place of the flying wire leads at Molex connectors J1 and J2.
Binary inputs are configurable and may be used for the following functions:

Input

Default input function

Additional functions

Compressor Safety

Fire Shutdown

Enthalpy Switch

Fan Status
Filter Status
Remote Occupancy
Door Contact
Fan Status
Filter Status
Remote Occupancy
Door Contact
Fan Status
Filter Status
Remote Occupancy
Door Contact

HumidiStat

Fan Status
Filter Status
Remote Occupancy
Door Contact

J11 Outputs

RTU Open

Installation

NOTE Output relay contacts rated at 3A, 24V maximum. Install pilot relays required by application.

NOTE J20 Analog Inputs 10 and 11 are reserved for a 10k Ohm space temperature sensor with an
optional 100k Ohm offset potentiometer used for setpoint adjustment.

Wiring sensors to inputs
You may wire various sensors to the RTU Open's inputs. See the table below for details.
NOTE This document gives instructions for wiring the sensors to the RTU Open. For specific mounting and
wiring instructions, see the Carrier Sensors Installation Guide.
All field control wiring that connects to the RTU Open must be routed through the raceway built into the corner
post. The raceway provides the UL-required clearance between high-and low-voltage wiring.

Pass the control wires through the hole provided in the corner post.

Feed the wires through the raceway to the RTU Open.

Connect the wires to the removable Phoenix connectors.

Reconnect the connectors to the board (where removed).

RTU Open

NOTE For rooftop unit installation, see the base unit installation instructions.

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could cause personal injury, death, and/or equipment damage.
Disconnect all power to the unit before performing maintenance or service. Unit may automatically start if
power is not disconnected.

Field-supplied sensor hardware
The RTU Open controller is configurable with the following field-supplied sensors:
Sensor

Part numbers

Space temperature sensor
(page 20)

SPS, SPPL, SPP, 33ZCT55SPT,
33ZCT56SPT, 33ZCT59SPT

Supply air temperature sensor
(page 21)

33ZCSENSAT

Duct air temperature sensor
(page 22)

33ZCSENDAT

Outdoor air temperature sensor
(page 23)

33ZCSENOAT

Factory-supplied with Economizer

CO2 sensor (page 24)

33ZCSENCO2, 33ZCT55CO2,
33ZCT56CO2

Required only for demand control
ventilation - a dedicated 24-vac
transformer is required

Outdoor air quality sensor (page 33ZCTSENCO2
25)
Duct relative humidity sensor
(page 26)

33ZCSENDRH-01

Space relative humidity sensor
(page 26)

33ZCSENSRH-01

Humidistat (page 27)

TSTATCCPLH01-B

CO2 aspirator box (page 24)

C33ZCCASPCO2

Outdoor air enthalpy switch
(page 28)

33CSENTHSW

Return air enthalpy sensor
(page 28)

33CSENTSEN

Filter status switch (page 31)

33CSFS-01

Fan status switch (page 31)

33CSAS-01 or field-supplied

Notes

Factory-installed

Optional with demand control
ventilation

Required for CO2 return duct/outside
air applications

Optional with
33CSSENTHSW

For specific details about sensors, see the Carrier Sensors Installation Guide.

RTU Open

Installation

Wiring an SPT sensor
The RTU Open is connected to a wall-mounted space temperature sensor to monitor room temperature.
An i-Vu Open Control System offers the following SPT sensors:
Sensor

Part #

Features

SPT Standard

SPS

•
•

Local access port
No operator control

SPT Plus

SPPL

SPT Pro

SPP

•
•
•
•
•
•
•
•

Slide potentiometer to adjust setpoint
MANUAL ON button to override schedule
LED to show occupied status
Local access port
LCD display
MANUAL ON button to override schedule
WARMER and COOLER buttons to adjust setpoint
INFO button to cycle through zone and outside air temperatures,
setpoints, and local override time
Local access port

•

You wire SPT sensors to the RTU Open's Rnet port. An Rnet can consist of any of the following combinations
of devices wired in a daisy-chain configuration:
•
•
•
•

1 SPT Plus or SPT Pro
1–4 SPT Standards
1–4 SPT Standards, and 1 SPT Plus or SPT Pro
Any of the above combinations, plus up to 2 BACview6's but no more than 6 devices total

NOTES
•

If you have 2 BACview6's, the second BACview6 must have a separate power supply with the same
ground as the controller.

•

If the Rnet has multiple SPT Standard sensors, you must give each a unique address on the Rnet. See
the Carrier Sensors Installation Guide.

•

If the Rnet has multiple BACviews, you must give each a unique address on the Rnet. See the BACview
Installation and User Guide.

Rnet wiring specifications
NOTE Use the specified type of wire and cable for maximum signal integrity.

Description

4 conductor, unshielded, CMP, plenum rated cable

Conductor

18 AWG

Maximum length

500 feet (152 meters)

Recommended coloring

Jacket: White
Wiring: Black, white, green, red

UL temperature rating

32–167°F (0–75°C)

RTU Open

Voltage

300 Vac, power limited

Listing

UL: NEC CL2P, or better

To wire the SPT sensor to the controller
1

Partially cut, then bend and pull off the outer jacket of the Rnet cable(s). Do not nick the inner insulation.
Strip about .25 inch (.6 cm) of the inner insulation from each wire.
Outer Jacket

.25 in.
(.6 cm)

Inner insulation

Wire each terminal on the sensor to the same terminal on the controller. See diagram below.
NOTE Carrier recommends that you use the following Rnet wiring scheme:
Connect this wire...

To this terminal...

Red

+12V

Black

Rnet-

White

Rnet+

Green

Gnd

Wiring a Supply Air Temperature sensor
Part #33ZCSENSAT
The RTU Open requires a temperature sensor installed in the supply air stream. The Supply Air Temperature
(SAT) sensor is used when the rooftop unit is equipped with electric heating.

RTU Open

Installation

Wiring specifications
Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

To wire the SAT sensor to the controller
1

Connect the wiring harness (OPN-RTUHRN). For details, see To wire inputs and outputs (page 14).

Wire the sensor to the wiring harness. See diagram below.

Connect to J2 wires 1 and 2.

Verify your sensor readings.

Wiring a Duct Air Temperature sensor
Part #33ZCSENDAT
The RTU Open requires a temperature sensor installed in the supply air stream. The Duct Temperature (DAT)
sensor is generally used when the rooftop unit is NOT equipped with electric heating.

Wiring specifications

Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

RTU Open

To wire a duct sensor to the controller
1

Connect the wiring harness (Part#OPN-RTUHRN). For details, see To wire inputs and outputs (page 14).

Wire the sensor to the wiring harness. See diagram below.

Connect to J2 wires 1 and 2.

Verify your sensor readings.

Drill .25" diameter hole. Pass sensor leads through bushing and insert assembly into hole. Secure leads
to ductwork with aluminum tape.

NOTE Sensor termination requires installation of RTU Open wiring harness assembly (Part #OPN-RTUHRN).

Wiring an Outdoor Air Temperature sensor
Part #33ZCSENOAT
Outdoor Air Temperature (OAT) is required to utilize all of the RTU Open’s features. OAT may be provided by a
local sensor (shown below) or a linked sensor in another controller. See Single Point Linkage (page 73).

Wiring specifications
Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

To wire an OAT sensor to the controller

RTU Open

Connect the wiring harness (Part#OPN-RTUHRN). For details, see To wire inputs and outputs (page 14).

Wire the sensor to the wiring harness. See diagram below.

Installation

Connect to J2 wires 3 and 4.

Verify your sensor readings.

Wiring a CO2 sensor
Part #33ZCSENCO2 (Display model)
Part #33ZCT55CO2 (No display)
Part #33ZCT56CO2 (No display)
A CO2 sensor monitors carbon dioxide levels. As CO2 levels increase, the RTU Open adjusts the outside air
dampers to increase ventilation and improve indoor air quality. A CO2 sensor can be wall-mounted or
mounted in a return air duct. Duct installation requires an Aspirator Box Accessory (Part #33ZCASPCO2).
The sensor has a range of 0–2000 ppm and a linear 4-20 mA output. The CO2 sensor’s power requirements
exceed what is available at J4 - 1 and 4. Provide a dedicated 24Vac transformer or DC power supply

Wiring specifications
Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

To wire the CO2 sensor to the controller

Wire the sensor to the controller. See appropriate diagram below.

Install a field-supplied dedicated 24 Vac transformer or DC power supply.

Wire the sensor to the controller.

RTU Open

Wiring diagram for #33ZCSENCO2:

Wiring diagram for #33ZCT55/56CO2:

Wiring an Outdoor Air Quality sensor
Part #33ZCSENCO2 (Display model)
An outdoor air quality (OAQ) sensor monitors outside air carbon dioxide levels. The RTU Open uses this
information, in conjunction with a CO2 sensor, to adjust the outside air dampers to provide proper ventilation.
An OAQ sensor is typically duct-mounted in the outside air stream. Duct installation requires an Aspirator Box
Accessory (Part #33ZCASPCO2).

RTU Open

Installation

The sensor has a range of 0–2000 ppm and a linear 4-20 mA output. The CO2 sensor’s power requirements
exceed what is available at J4 - 1 and 4. Provide a dedicated 24 Vac transformer or DC power supply.

Wiring specifications
Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

To wire the OAQ sensor to the controller
1

Wire the sensor to the controller. See appropriate diagram below.

Install a field-supplied dedicated 24 Vac transformer or DC power supply.

Apply power and verify sensor readings.

Wiring diagram for #33ZCSENCO2:

NOTE Sensor may be terminated at Input 1 or 2.

Wiring a Relative Humidity sensor
Wall sensor - Part #33ZCSENSRH-01
Duct sensor - Part #OPNSENRH-01
The Relative Humidity (RH) sensor may be used for zone humidity control (dehumidification) when applied to
a Carrier rooftop unit equipped with the Humidi-MiZer™ option. On units not equipped for dehumidification,
the sensor monitors humidity, but provides no control.
NOTE You cannot use a relative humidity sensor when using both a CO2 and OAQ sensor on the controller.

RTU Open

Wiring specifications
Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

To wire the RH sensor to the controller
1

Strip the outer jacket from the cable for at least 4 inches (10.2 cm). Strip .25 inch (.6 cm) of insulation
from each wire.

Wire the sensor to the controller. See diagram below.

Apply power and verify sensor readings.

NOTE Sensor may be terminated at Input 1 or 2.

Wiring a Humidistat
Locally Purchased
A humdistat may be used for zone humidity control (dehumidification) when applied to a Carrier rooftop unit
equipped with the Humidi-MiZer™ option. On units not equipped for dehumidification, the humidistat will
indicate a high humidity condition only.

Wiring specifications

RTU Open

Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

Installation

To wire a humidistat to the controller
1

Strip the outer jacket from the cable for at least 4 inches (10.2 cm). Strip .25 inch (.6 cm) of insulation
from each wire

Wire the humidistat to the controller. See diagram below.

Apply power and verify sensor readings.

NOTE Humidistat may be return duct or space mounted.

Wiring an enthalpy switch
Outdoor Air - Part #33CSENTHSW
Return air - Part #33CSENTSEN
The 33CSENTHSW is an outdoor air enthalpy switch/receiver. This control determines the suitability of the
outdoor air as a cooling source, based on the heat content of the air. Differential enthalpy control requires
installing a 33CSENTSEN enthalpy sensor in the rooftop unit's return air duct.

Wiring specifications

Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

RTU Open

To wire an enthalpy switch (outdoor air) to the controller
An enhalpy switch is typically mounted in the outdoor air inlet.
Wiring diagram for a field-installed enthalpy switch:

NOTES

RTU Open

•

Factory-installed enthalpy switches terminate at J2 wires 6 (switch input) and 7 (24 Vac).

•

Input channel must be configured for the enthalpy contact (N.O. or N.C.) that you use.

Installation

Wiring diagram for factory-installed enthalpy switch:

NOTE Factory-installed enthalpy switches terminate at J2 wires 6 (switch input) and 7 (24 Vac).

To wire an enthalpy switch (differential) to the controller

RTU Open

Wiring diagram for optional enthalpy sensor mounted in the return air for differential enthalpy:

Wiring a status switch
Filter - Part #33CSFS-01 or field-supplied
Fan status - Part #33CSAS-01 or field-supplied
Filter and/or fan status switches may be installed to provide a Dirty Filter indication or Fan Running status.

Wiring specifications

RTU Open

Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

Installation

To wire a status switch to the controller

NOTES
•

Binary inputs 3, 5, 8, and 9 are configurable and may be used for Fan Status, Filter Status, Remote
Occupancy, or Door Contacts, if they have not already been used for their default functions.

•

Follow device manufacturer's installation and operating instructions.

Wiring a compressor safety
This is typically provided by the manufacturer with the rooftop equipment. A compressor safety status may be
monitored if available.

Wiring specifications

Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

RTU Open

To wire a compressor safety input to the controller

NOTES
•

An isolation relay may be required if the RTU Open is powered separately from the equipment's control
power circuit.

•

Follow device manufacturer's installation and operating instructions.

Wiring an occupancy switch or door contact
Occupancy switch - field-supplied
Door contact - field-supplied
Occupancy or door contact switches may be installed to provide an alternate means of occupancy
determination or heating and cooling lockout. See Sequence of Operation (page 42) for additional details.

Wiring specifications

RTU Open

Cable from sensor to controller:

If <100 ft (30.5 meters)
If >100 ft (30.5 meters)

Maximum length:

500 feet (152 meters)

22 AWG, unshielded
22 AWG, shielded

Installation

To wire an occupancy switch or door contact

NOTES

•

Binary Inputs 3, 5, 8, and 9 are configurable and may be used for Fan Status, Filter Status, Remote
Occupancy, or Door Contacts - provided they have not been utilized for their default functions.

•

Follow device manufacturer's installation and operating instructions.

RTU Open

Start-up
To start up the RTU Open, you need one of the following user interfaces to the controller. These items let you
access the controller information, read sensor values, and test the controller.
This interface...

Provides a...

i-Vu Open software

Permanent interface

Field Assistant software runs on a laptop connected to controller's Local Access port 1

Temporary interface

Virtual BACview software runs on a laptop connected to controller's Local Access port 1, 2

Temporary interface

BACview6 Handheld keypad/display unit connects to controller's Local Access port 1, 2

Temporary interface

BACview6 keypad/display unit
connected to controller's Rnet port 2

Permanent interface

1
2

RTU Open

Requires a USB Link (USB-L).
See the BACview Installation and User Guide for instructions on connecting and using the above items.

Start-up

Service Test
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Service Configuration > Service Test
HOME > CONFIG > SERVICE > TEST

Service Test can be used to verify proper operation of compressors, heating stages, indoor fan, power
exhaust fans, economizer, and dehumidification. It is highly recommended to use Service Test at initial
system start-up and during troubleshooting. See Appendix A: Points/Properties (page 58) for more
information.
Service Test differs from normal operation as follows:
•

Outdoor air temperature limits for cooling circuits, economizer, and heating are ignored.

•

Normal compressor time guards and other staging delays are ignored.

•

Alarm statuses (except Fire and Safety Chain) are ignored, but all alarms and alerts are still broadcast on
the network, if applicable.

Service Test can be turned on or off from BACview, Field Assistant, or i-Vu. Select Default Value of Enable to
turn on and Disable to turn off.
NOTES
•

Service Test mode is password-protected when accessed from a BACview.

•

Service Test allows testing of each controller output.

•

Binary Service Test functions are on when the Default Value is set to Enable and off when set to Disable.

•

The output of the Analog Service Test is controlled by the percentage (0-100%) entered into the Default
Value.

•

It is recommended to return every Service Test variable to Disable or 0.00 after testing each function
(unless that test variable must be active to test a subsequent function, as in Compressor 2 Test).

•

All outputs return to normal operation when Service Test is set to Disable.

Service Test functions

•

Use Fan Test to activate and deactivate the Supply Fan (BO - 1) output. Note that this output may enable
simultaneously with other Service Test modes even with its Default Value set to Disable.

•

Use Compressor 1 Test to activate and deactivate the Compressor 1 (BO - 5) output. The Supply Fan
output will be activated and deactivated in conjunction with this output. Leave Compressor 1 Test on
Enable if Compressor 2 Test is required.

•

Use Compressor 2 Test to activate and deactivate the Compressor 2 (BO - 4) output. Always test the
Compressor 1 output first. Compressor 1 Test output must be set to Enable for Compressor 2 Test to
function.

•

Use the Reversing Valve Test to activate and deactivate the reversing valve (BO - 7) output.

•

Use the Dehumidification Test to activate and deactivate the Humidi-MiZer™ (BO - 6) output. The Supply
Fan output will be activated and deactivated in conjunction with the Dehumidification Test output.

•

Use Heat 1Test to activate and deactivate the Heat 1 (BO - 3) output. The Supply Fan output is activated
and deactivated in conjunction with the Heat 1Test output.

•

Use Heat 2Test to activate and deactivate the Heat 2 (BO - 2) output. The Supply Fan output is activated
and deactivated in conjunction with the Heat 2Test output.

RTU Open

•

Use Power Exhaust Test to activate and deactivate the power exhaust (BO - 8) output.

•

Use Economizer Test to set the (AO - 1) economizer output to any value from 0 to 100% of configured
output (2-10 Vdc or 4-20 mA).

•

Analog Output 2 Test (AO - 2) is currently unused and does not require testing.

•

Service Test mode does not timeout. Return all test variables to Disable or 0.00. Set Service Test to
Disable or cycle power to the RTU Open to return to normal operation.

Configuring the RTU Open's properties
To start up the RTU Open, you need to configure the properties described in the following sections. These
properties affect the unit operation and/or control. Review and understand the meaning and purpose of each
property before changing it.
•
•
•

Unit Configuration properties (page 37)
Setpoint Configuration properties (page 39)
Service Configuration properties (page 40)

See Appendix A (page 58) for a complete list of the controller's points/properties.

Unit Configuration properties
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Unit Configuration
HOME > CONFIG > UNIT

Point Name/Description

Default/Range

Fan Mode – The supply fan's operating mode.

Continuous

Options:
Auto - The fan cycles on/off in conjunction with heating or cooling.
Continuous - The fan runs continuously during occupancy & intermittently during
unoccupied periods with heating or cooling.
Always On - The fan runs continuously regardless of occupancy or calls for heating and
cooling.

Auto
Continuous
Always On

Occupancy Source - The method that the controller uses to determine occupancy.

Always Occupied

Options:
Always Occupied = Controller operates continuously as occupied.
BACnet Schedule = Controller follows a schedule set up in i-Vu or Field Assistant.
BAS On/Off = Occupancy is set over the network by another device or a third party BAS.
Remote Occ Input =Occupancy is set by a remote contact.

Always Occupied
BACnet Schedule
BAS On/Off
Remote Occ Input

Input 1 Function – The type of sensor (4-20 mA) connected to terminals J4 – 4, 5, & 6.

No Sensor

No Sensor
IAQ Sensor
OAQ Sensor
Space RH Sensor

RTU Open

Start-up

Point Name/Description

Default/Range

Input 2 Function – The type of sensor (4-20 mA) connected to terminals J4 – 1, 2, & 3.

No Sensor

No Sensor
IAQ Sensor
OAQ Sensor
Space RH Sensor

Input 3 Function – The usage of Input 3. You must also set Input 3 Switch Configuration.

Compressor Safety

Options:
No Function – The input is not used.
Compressor Safety – Safety device status.
Fan Status – Proves supply fan operation.
Filter Status – Indicates a dirty filter.
Remote Occupancy – Sets occupancy using a hardware contact.
Door Contact – Sets occupancy using a hardware contact.

No Function
Compressor Safety
Fan Status
Filter Status
Remote Occupancy
Door Contact

Input 3 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

Input 5 Function – The usage of Input 5. You must also set Input 5 Switch Configuration.

Fire Shutdown

Options:
No Function – The input is not used.
Fire Shutdown – Fire Safety device status. Inhibits operation when tripped.
Fan Status – Proves supply fan operation.
Filter Status – Indicates a dirty filter.
Remote Occupancy – Sets occupancy using a hardware contact.
Door Contact – Sets occupancy using a hardware contact.

No Function
Fire Shutdown
Fan Status
Filter Status
Remote Occupancy
Door Contact

Input 5 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

Input 8 Function – The usage of Input 8. You must also set Input 8 Switch Configuration.

Enthalpy Switch

Options:
No Function – The input is not used.
Enthalpy Switch – Indicates enthalpy status (high or low).
Fan Status – Proves supply fan operation.
Filter Status – Indicates a dirty filter.
Remote Occupancy – Sets occupancy using a hardware contact.
Door Contact – Sets occupancy using a hardware contact.

No Function
Enthalpy Switch
Fan Status
Filter Status
Remote Occupancy
Door Contact

Input 8 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

Input 9 Function – The usage of Input 9. You must also set Input 9 Switch Configuration.

Humidistat

Options:
No Function – The input is not used.
Humidistat – Indicates high humidity condition.
Fan Status – Proves supply fan operation.
Filter Status – Indicates a dirty filter.
Remote Occupancy – Sets occupancy using a hardware contact.
Door Contact – Sets occupancy using a hardware contact.

No Function
Humidistat
Fan Status
Filter Status
Remote Occupancy
Door Contact

RTU Open

Point Name/Description

Default/Range

Input 9 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

T55

T55
T56 (Use for T59)
SPT Sensor
None

Space sensor type - The type of local space temperature sensor.

Setpoint properties
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Setpoints
HOME > CONFIG > SETPOINT

Select a color band on the setpoint graph to see the current setpoints in the Heating and Cooling fields. See setpoint
descriptions below.

Point Name/Description

Default/Range

Occupied Heating – Green
The heating setpoint the controller maintains while in occupied mode.

70°F

-40 to 245°F

Occupied Cooling – Green
The cooling setpoint the controller maintains while in occupied mode.

74°F

-40 to 245°F

Unoccupied Heating – Gray
The heating setpoint the controller maintains while in unoccupied mode.

55°F

45 to 100°F

90°F

-40 to 245°F

Unoccupied Cooling – Gray
The cooling setpoint the controller maintains while in unoccupied mode.

RTU Open

Start-up

Point Name/Description

Default/Range

Optimal Start – The earliest time, prior to occupancy, at which the Optimal Start function
may begin to adjust the effective setpoints to achieve the occupied setpoints by the time
scheduled occupancy begins. Enter 0 to disable Optimal Start.

4 hr

0 to 4 hr

Occ Relative Humidity Setpoint – The percentage of relative humidity in the space during
occupancy that will energize BO - 6 (Humidi-MiZer™).

60%rh

0 to Unoccupied
RH Control
Setpoint

Unocc Relative Humidity Setpoint – The percentage of relative humidity in the space during
the unoccupied time period that starts the unit and energizes BO - 6 (Humidi-MiZer™).

95%

30 to 100%

650ppm

0 to 9999 ppm

50% Open

20 to 90% Open

DCV Max Ctrl Setpoint – The design difference between indoor and outdoor CO2 levels.
Power Exhaust Setpoint - The outside air damper position at which the controller energizes
the Power Exhaust relay. Configuration >Service Configuration > Economizer Exists must be
set to Yes, and Configuration >Service Configuration > Continuous Occupied Exhaust must
be set to No.

Service Configuration properties
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Service Configuration
HOME > CONFIG > SERVICE

Point Name/Description

Default/Range

Unit Type – The type of equipment that the RTU Open is controlling.

Heat/Cool

Options:
Heat/Cool – Standard rooftop air handling unit.
HP O/B Ctrl – Heat Pump application, uses reversing valve output to control heating and
cooling.
HP Y1/W1 Ctrl – Carrier Heat Pump application only.

Heat/Cool
HP O/B Ctrl
HP Y1/W1 Ctrl

Compressor Stages – The number of mechanical cooling stages.

One Stage

One Stage
Two Stages

Economizer Exists – Set to Yes to enable economizer control for units equipped with an
economizer damper.

No/Yes

Reversing Valve Output – Set to O = Reversing Valve output on with cooling. Set to B =
Reversing Valve output on with heating.

O/B

Heat Type – The type of heating that the unit has.

Electric

Electric/Gas

1 /2 /0 (no heating)

Number Of Heat Stages – The number of heat stages.

RTU Open

Point Name/Description

Default/Range

Continuous Occupied Exhaust – Configures the exhaust fan control strategy (BO-8). If Yes,
the power exhaust runs continuously in occupied mode and is off in unoccupied mode. If
No, the power exhaust is controlled by the Power Exhaust Setpoint.

No/Yes

Indoor CO2 Sensor Value @min (ma) – The CO2 value that corresponds to a 4mA input at
the appropriate input channel.

0ppm

0 to 9999 ppm

Indoor CO2 Sensor Value @max (ma) – The CO2 value that corresponds to a 20mA input at
the appropriate input channel.

2000 ppm

0 to 9999 ppm

Outdoor CO2 Sensor Value @min (ma) – The CO2 value that corresponds to a 4 mA input
at the appropriate input channel.

0ppm

0 to 9999 ppm

2000 ppm

0 to 9999 ppm

Outdoor CO2 Sensor Value @max (ma) – The CO2 value that corresponds to a 20 mA input
at the appropriate input channel.

RTU Open

Sequence of Operation

Sequence of Operation
The RTU Open supports various types of constant volume air source configurations:
•

Standard heat/cool unit types with up to 2-stages of mechanical cooling and gas or electric heating

•

Heat pump units utilizing a reversing valve output for heating and cooling control

•

Heat pump unit (Carrier) with an OEM control board

•

Economizer, CO2, Demand Limiting, and RH control strategies are available for appropriately equipped
units

The RTU Open may operate as part of a linked VVT system or as a stand-alone controller.

Occupancy
The RTU Open’s operation depends upon its occupancy state (Occupied/Unoccupied). The RTU Open
operates continuously in the Occupied mode until you configure an occupancy schedule.
An occupancy schedule may be:
•

A local schedule configured in the controller using BACview or Field Assistant

•

A BACnet schedule configured in i-Vu, networked through an i-Vu Open Router

•

A BACnet or local schedule configured for subordinate VVT Zones, networked through an i-Vu Open
Router(s) and employing Linkage

To set up occupancy schedules, consult the documentation for your user interface.
NOTE A BACnet schedule, downloaded from i-Vu will overwrite a local schedule that was set up with BACview
or Field Assistant.
Occupancy Source - the following settings determine occupancy. See Unit configuration (page 59).
Options:

•

Always Occupied – Controller operates continuously, regardless of any configured schedule

•

BAS On/Off – Occupancy is set over the network by another device or a third party BAS. Refer to the RTU
Open Integration Guide for additional instructions in communication protocols.

•

Remote Occ Input – Controller monitors an input contact connected to one of the available binary inputs
configured to receive it. You must set Unit Configuration > Occupancy Source to Remote Occ Input and
one Input Switch Configuration to Remote Occupancy.

RTU Open

Supply fan
The RTU Open supply fan may be configured for one of three Fan Modes:
•

Auto - The fan cycles on/off in conjunction with heating or cooling

•

Continuous - The fan runs continuously during occupancy and intermittently during unoccupied periods
with heating or cooling

•

Always On - The fan runs continuously regardless of occupancy or calls for heating and cooling

Occupancy can be determined by Linkage, BACnet schedules, BAS schedules, or in response to a remote
occupancy switch.
A Unit Start Delay is used when transitioning from Unoccupied to Occupied. A Fan Off Delay allows the supply
fan to continue operating after heating or cooling stops.
If the following alarms are active, the fan turns off immediately, regardless of the occupancy state or demand:
Fire Shutdown
•
•
Safety chain
•
SAT alarm
•
SPT alarms
The RTU Open does not include smoke-control functions such as smoke-purge, zone-pressurization, or smokeventilation. Each of these modes require a field-designed circuit to operate the following, as required by local
fire codes:
•
RTU supply fan
•
RTU economizer
•
RTU power exhaust
The RTU Open may be configured to accept a Supply Fan Status input to provide proof the supply fan is
operating. When enabled, a loss or lack of fan status will stop heating and cooling operation.
A Supply Fan Alarm Service Timer function is available to track the number of supply fan run hours and
generate an alarm when the accumulated runtime exceeds the set threshold.

Cooling
The RTU Open's application and configuration determines the specific cooling sequence. The RTU Open can
control up to two stages of cooling with an additional output for a reversing valve (heat pump applications).
The following conditions must be true for the cooling algorithm to operate:

RTU Open

•

Outdoor Air Temperature is greater than the Cooling Lockout Temperature setpoint

•

The indoor fan has been on for at least 30 seconds

•

The unit has a valid Supply Air Temperature input

•

The unit has a valid Space Temperature input

•

Heat mode is not active and the time guard between modes has expired

•

Economizer is active and open > 85% with SAT > (Minimum Cooling SAT + 5°F) and SPT > Effective
Cooling Setpoint + 0.5°F, or the Economizer is unavailable

Sequence of Operation

The cooling relays are controlled by the Cooling Control PID Loop and Cooling Stages Capacity algorithm. They
calculate the desired number of stages needed to satisfy the space by comparing the Space Temperature to
the:
•

Effective Occupied Cooling Setpoint when occupied

•

Effective Unoccupied Cooling Setpoint when unoccupied

When the cooling algorithm preconditions have been met, the compressors are energized in stages, as
applicable. Anti-recycle timers are employed to protect the equipment from short-cycling. There are fixed
three-minute minimum on-times, and five-minute off-times for each compressor output.
During compressor operation, the RTU Open may reduce the number of active stages if the rooftop supply air
temperature falls below the Minimum Cooling SAT Setpoint. A compressor staged off in this fashion may be
started again after the normal time-guard period has expired, if the Supply Air Temperature has increased
above the Minimum Cooling SAT Setpoint.
Compressor 2 Service Alarm Timer functions are available (one for each stage of compression). This function
tracks the number of compressor run hours and generates an alarm when the accumulated runtime exceeds
the threshold set by the adjustable compressor service alarm timers.

Economizer
The RTU Open provides an analog economizer output for rooftop units with economizer dampers. Economizer
dampers may be used to provide free cooling and indoor air quality control when outside air conditions are
suitable.
The following conditions must be true for economizer operation:
•

The Outdoor Air Temperature is less than the Space Temperature and less than the Economizer High
OAT Lockout Temp setpoint

•

The indoor fan has been on for at least 30 seconds

•

The unit has a valid Supply Air Temperature input

•

The unit has a valid Space Temperature input

If any of the preceding conditions are not true, the economizer will be set to the Vent Dmpr Pos / DCV Min
Pos setpoint.
If all preceding conditions are true, the economizer PID loop will modulate the damper from the Vent Dmpr
Pos / DCV Min Pos setpoint.
The economizer moves to the Vent Dmpr Pos / DCV Min Pos setpoint if the SAT falls below the Minimum
Cooling SAT (+ 5°F).

Power Exhaust
The RTU Open may enable and disable an exhaust fan, based on either the controller’s occupancy or its
economizer damper position.
If Continuous Occupied Exhaust is Yes, the Power Exhaust binary output (BO-8) is energized while theRTU
Open is occupied and de-energized when unoccupied.
If Continuous Occupied Exhaust is No, the Power Exhaust binary output (BO-8) is energized when the
economizer damper output exceeds the Power Exhaust Setpoint value (default = 50%). The output remains
energized until the economizer output falls below the Power Exhaust Setpoint value by a fixed hysteresis of
10%.

RTU Open

Unoccupied Free Cooling
Unocc Free Cool Enable allows rooftop equipment with an economizer damper to utilize outdoor air for free
cooling during unoccupied periods.
The following conditions must be true for unoccupied free cooling to operate:
•

Unocc Free Cool Enable set to Enable

•

The system is unoccupied

•

The outside air temperature is below the Economizer High OAT Lockout Temp setpoint

•

The outside air temperature is less than the space temperature

•

Enthalpy (if enabled) is Low

When the RTU Open schedule is unoccupied and the space temperature rises at least 1° above the Occupied
Cooling Setpoint, the supply fan starts. The economizer damper opens as necessary to cool the space. The
RTU Open continues to operate in this mode until the space is satisfied or the outside air conditions are no
longer suitable for free cooling.

Optimal Start
The RTU Open may utilize Optimal Start. Optimal Start adjusts the effective setpoints to achieve the occupied
setpoints by the time scheduled occupancy begins.The Optimal Start recovery period may begin as early as 4
hours prior to occupancy. The algorithm works by moving the unoccupied setpoints toward the occupied
setpoints. The rate at which the setpoints move is based on the outside air temperature, design
temperatures, and capacities.
The following conditions must be true for unoccupied free cooling to operate:
•

On the Properties page > Equipment tab > Configuration > Setpoints > Optimal Start, the Default Value
must be set greater than 0 and less than or equal to 4 (0.00 disables Optimal Start).

•

The system is unoccupied

NOTE If the Open controller does not have a valid outside air temperature, then a constant of 65° F is used.
This value is not adjustable.

RTU Open

Sequence of Operation

The actual equation that the controller uses to calculate Optimal Start is nonlinear. An approximation of the
result is shown below.

To change Optimal Start settings:
1

In the navigation tree, select the equipment that you want to change.

Click Properties page > Equipment tab > Configuration > Setpoints.

Enthalpy control
You may use an enthalpy switch to indicate the suitability of outdoor air for economizer cooling. You can use
either an outdoor air or differential enthalpy switch. A differential enthalpy switch has a sensing device in both
the outdoor and return air streams. A differential enthalpy switch indicates when outside air is cooler than the
return air, and is available for economizer cooling. If no enthalpy switch is configured, a network point (Object
Name: oae) is available. This point is displayed in i-Vu and BACview as Enthalpy (BACnet).
The sequence of operation for economizer cooling is the same with or without an enthalpy switch, except that
an enthalpy switch imposes one more validation on the suitability of outside air for economizer cooling. An
Enthalpy Status that is High disables the economizer and the outside air damper goes to its minimum
position. An Enthalpy Status that is Low enables the economizer if a call for cooling exists and the remaining
preconditions are met.

Indoor Air CO2
Indoor Air CO2 is controlled on rooftop equipment with an economizer. Indoor Air CO2 sequence is enabled
by installing an air quality (CO2) sensor. A CO2 sensor may be terminated at the RTU Open, or a subordinate
zone controller, when part of a zoned system.
An outdoor air quality sensor may also be installed and terminated at the RTU Open, but it is not required.
When an outdoor air quality sensor is not installed, the algorithm uses 400ppm as the fixed outdoor air CO2
level.

RTU Open

The following conditions must be true for the Indoor Air CO2 algorithm to operate:
•

The system is occupied

•

The supply fan has been started for at least 30 seconds

•

The CO2 sensor has a valid reading

As the air quality within the space changes, the minimum position of the economizer damper changes, which
allows more or less outdoor air into the space, depending on the relationship of the indoor air CO2 level to the
differential setpoint.
The Indoor Air CO2 algorithm calculates a minimum position value using a PID loop. The CO2 minimum
damper position is then compared against the Vent Dmpr Pos / DCV Min Pos setpoint and the greatest value
becomes the final minimum damper position of the economizer output.
The degree to which the outside air damper may be opened by the Indoor Air CO2 algorithm is limited by the
DCV Max Vent Damper Pos setpoint, which is adjustable between ten and sixty percent (10 – 60%).

Heating
The specific heating sequence is determined by the controller's application and configuration. The RTU Open
controls up to two stages of gas or electric heating with an additional output for a Reversing Valve (Heat
Pump applications).
The following conditions must be true for the heating algorithm to operate:
•

The Outdoor Air Temperature is less than the Heating Lockout Temperature setpoint

•

The indoor fan has been ON for at least 30 seconds

•

The unit has a valid Supply Air Temperature input

•

The unit has a valid Space Temperature input

•

Neither Cool mode nor economizer are active and the time guard between modes has expired

The heating relays are controlled by the Heating Control PID Loop and Heating Stages Capacity algorithm,
which calculate the desired number of stages to satisfy the space by comparing the Space Temperature to
the:
•

Effective Occupied Heating Setpoint when occupied

•

Effective Unoccupied Heating Setpoint when unoccupied

When the heating algorithm preconditions have been met, the heating is energized in stages. Anti-recycle
timers are employed to protect the equipment from short-cycling. There are fixed one minute minimum on
and off times for each heating output.
During heating operation, the RTU Open may reduce the number of active stages if the rooftop Supply Air
Temperature exceeds the Maximum Heating SAT setpoint. A heat stage turned off in this fashion may be
started again after the normal time-guard period has expired, if the Supply Air Temperature has decreased
below the Maximum Heating SAT setpoint.

RTU Open

Sequence of Operation

Heat Pump operation
The RTU Open can control heat pumps HP O/B and Y1/W1.
HP O/B provides a separate output (BO-7) to control a reversing valve. The reversing valve control may be
configured to be energized with a call for heating (B), or energized with a call for cooling (O).
The sequence of operations are as previously described for heating and cooling except that the Y1 and Y2
outputs are compressor outputs, energizing mechanical heating or cooling, depending on the state of the
reversing valve. W1 and W2 are used for auxiliary heat. Up to two stages are available.
Selection Y1/W1 is for heat pumps that do not require a O terminal to energize the reversing valve. The
sequences of operations are as described for Heating (page 47) and Cooling (page 43). The reversing valve
output is not utilized in this application. W1 and W2 are used for auxiliary heat. Up to two stages are
available.

Dehumidification
The RTU Open provides occupied and unoccupied dehumidification on units that are equipped with the
Carrier Humidi-MiZer™ option from the factory. This requires a space relative humidity sensor or a humidistat
for control.
The following conditions must be true for the dehumidification control to operate:
•

The Outside Air Temperature is greater than the Cooling Lockout Temperature setpoint

•

The Indoor Fan has been ON for at least 30 seconds

•

The unit has a valid Supply Air Temperature input

•

The unit has a valid Space Temperature input

•

The unit has a valid Space Relative Humidity Sensor or Humidistat input

•

Heat mode is not active and the time guard between modes has expired

When using a relative humidity sensor to control dehumidification, occupied and unoccupied dehumidification
setpoints are used.
When using a humidistat, the setpoints are not used. The humidistat indicates a high-humidity condition.
When a high indoor relative humidity condition is indicated and the above conditions are satisfied, the RTU
Open enters the dehumidification mode, energizing the Humidi-MiZer™ output.
The mode continues until the space relative humidity falls below the active setpoint by a 5% fixed Hysteresis
when a humidity sensor is used, or when there is no longer a call for dehumidification where a humidistat is
used.
See the base unit / Humidi-MiZer™ operations manual for additional information.

RTU Open

Demand Limit
The RTU Open may employ a demand limit strategy. Demand limiting in the RTU Open works through setpoint
expansion. The controller’s heating and cooling setpoints are expanded in steps or levels. The degree to
which the setpoints are expanded is defined by the Demand Level Setpoints.
Each Demand Level (1 through 3) adjusts the heating and cooling setpoints outwards. By default, Demand 1
yields a 1° expansion, Demand 2 yields a 2° expansion, and Demand 3 yields a 4° expansion.
The BACnet Demand Limit variable sets the desired level of setpoint expansion in the receiving controller.
Level 0 leaves the standard occupied and unoccupied heating and cooling setpoints in effect. Levels 1
through 3 expands occupied heating and cooling setpoints.

Door switch
A Door Contact may be configured on any unused binary input. A typical application is an occupancy sensor
mounted within the space served by a single zone rooftop. Door Contact disables mechanical cooling and
electric or gas heating, when active. Economizer cooling, if available, continues to operate.

Remote occupancy
Remote occupancy may be configured on any unused binary input channel. A typical application is a remote
contact, controlled by a third party, to set the controller's occupied mode. The Remote Occupancy function
requires both an input configured for Remote Occupancy, and Occupancy Source set to Remote Occ Input to
operate.
Once configured, the controller will operate in the occupied or unoccupied mode, as determined by the state
of the Remote Occupancy input.

Fire Shutdown
Fire Shutdown may be configured on Binary Input 5. A typical application involves a smoke detector or fire
shutdown contact, which, when active, immediately shuts down equipment operation.

Compressor Safety
Compressor Safety may be configured on Binary Input 3. A compressor safety tripped indicator circuit is
available on most Carrier rooftop equipment.
A Compressor Safety Alarm is shown on Properties page > Equipment tab > Alarms and indicates that the
equipment requires attention.

RTU Open

Sequence of Operation

Cooling, heating, and supply fan outputs are not interrupted except where the RTU Open is configured for
Heat Pump operation. When configured for Heat Pump, and in the heating mode, a compressor safety fault
will cause the available stages of electric heating to be enabled in place of mechanical heating.
Normal operation resumes when the compressor safety circuit is de-energized.

Fan Status
Fan Status may be configured on any unused binary input channel. A typical application would be an airflow
switch, current sensing relay, or other device that provides a supply fan running verification.
Enabling this function displays the supply fan’s status on the equipment graphic.
If the controller loses fan status during operation, heating and cooling are disabled, the economizer damper
(if available) is closed, and an alarm for loss of status is indicated.
If the fan status is on when the controller is commanding the fan off, the unit remains in the off state. An
alarm is generated indicating that the fan is running when it should be off.

Filter Status
Filter status may be configured on any unused binary input channel. A typical application is a differential
pressure switch that senses the pressure drop across a filter bank.
When the pressure across the filter bank exceeds the setpoint of the differential pressure switch, the Filter
status is displayed as Dirty on the controller graphic. An alarm indicates a dirty filter.

Alarms
NOTE Some of the Alarms functions described in this section will only be visible on the Properties page >
Equipment tab > Alarms when the appropriate inputs are configured. Alarms are not initiated when the input
is not configured.
Safety Chain - You may use the RTU Open's safety chain circuit to shut down the unit for a safety condition.
Examples: Low or High Temperature Cutouts (Freezestat / Firestat). See To wire inputs and outputs (page 14)
for additional wiring instructions. This alarm indicates the safety chain circuit (Input 4) is open. Cooling,
heating, and supply fan operation stop after appropriate time guards. Normal operation resumes when the
safety chain circuit is complete.
Fire Shutdown – You may configure the RTU Open to accept a Fire Shutdown contact on Input 5. Examples:
Smoke detectors or fire shutdown relays. This alarm indicates this device (Input 5) has tripped. Cooling,
heating, and supply fan operation immediately stop. Reset fire shutdown contact to resume normal operation.
Compressor Safety – You may configure the RTU Open to monitor the base unit’s compressor safety circuit.
This alarm indicates the base unit's compressor safety circuit is energized. Cooling, heating, and supply fan
outputs are not interrupted except when the RTU Open is configured for Heat Pump. Normal operation
resumes when the compressor safety circuit is de-energized.
If the Heat Pump is in the heating mode, it will automatically replace the compressor stage(s) with the
equivalent number of auxiliary heat stages, as available.
•

If it's a Carrier Heat Pump, there is only one auxiliary heat stage output and the staging is done by the
machine itself, if it's two-stage gas or electric.

RTU Open

•

For a non-Carrier Heat Pump, when configured for two stages of aux heat and two compressors,
Compressor 1 is replaced by Aux Heat Stage 1 and Compressor 2 is replaced by Aux Heat Stage 2.

The compressor output stays on when the safety alarm is present. For cooling, the alarm indicates the
compressors are down. See Heat Pump operation (page 48) for further information.
Space Temp Sensor – This alarm indicates an invalid sensor condition in a physically connected space
temperature sensor (SPT Sensor/T5*). Cooling, heating, and supply fan operation stop after the appropriate
time guards. Normal operation resumes when the controller detects a valid sensor.
Supply Air Temp Sensor – This alarm indicates a shorted or open circuit in the SAT input. Cooling, heating,
and supply fan operation stops after the appropriate time guards. Normal operation resumes when the
controller detects a valid sensor.
Outdoor Air Temp Sensor Alarm - This alarm indicates a shorted or open circuit in the OAT input. Cooling,
heating, and supply fan operation continues. OAT lockouts will not operate while the sensor is in alarm.
Normal operation resumes when the controller detects a valid sensor.
Space Relative Humidity Sensor - This alarm indicates if the mA input at the associated channel falls below
3.5 mA or rises above 21 mA. Cooling, heating, and supply fan operation continues, however, the controller’s
Humidi-MiZer™ binary output is disabled until the fault condition is corrected.
IAQ Sensor - The RTU Open generates an IAQ Sensor alarm if the mA input at the associated channel falls
below 3.5 mA or rises above 21 mA. Cooling, heating, and supply fan operation continues. However, the
controller’s IAQ control function is disabled until the fault condition is corrected.
OAQ Sensor - The RTU Open generates an OAQ Sensor alarm if the mA input at the associated channel falls
below 3.5 mA or rises above 21 mA. Cooling, heating, and supply fan operation continues. However, the
controller’s IAQ control function uses 400ppm as the fixed outdoor air CO2 level until the fault condition is
corrected.
Space Temperature –
•

Occupied - The RTU Open generates a Low Space Temperature alarm if the space temperature falls
below the lower limit of the blue color bar. A High Space Temperature alarm is generated if the space
temperature rises above the upper limit of the orange color bar.

•

Unoccupied An unoccupied low space temperature alarm is generated when the space temperature falls
below the Alarm Configuration > Unoccupied Low SPT Alarm Limit. An unoccupied high space
temperature alarm is generated when the space temperature rises above the Alarm Configuration >
Unoccupied High SPT Alarm Limit.

The following values are related to the Space Temperature alarm:
•

Alarming Temperature – This variable displays the value of the space temperature that is in alarm and is
only visible when the space temperature is in an alarm state.

•

Alarm Limit Exceeded – This variable displays the value of the alarm setpoint that is exceeded by the
alarming space temperature and is only visible when the space temperature is in an alarm state.

High Supply Air Temperature – The RTU Open generates this alarm when the supply air temperature exceeds
the Alarm Configuration > High SAT Alarm Limit setpoint for 5 minutes. This alarm is inhibited until the RTU
has been running for 30 minutes to allow for system stabilization after startup.
Low Supply Air Temperature - The RTU Open generates this alarm when the supply air temperature falls
below the Alarm Configuration > Low SAT Alarm Limit setpoint for 5 minutes. This alarm is inhibited until the
RTU has been running for 30 minutes to allow for system stabilization after startup.
Setpoint Slider – The RTU Open generates this alarm when an open circuit is detected at Input 11 and the
RTU Open Configuration > Unit Configuration > Input Configuration > Space sensor type is set to T56. Note
that only an open circuit results in an alarm. A short across this input offsets the setpoints negatively by the
amount configured in the Unit Configuration > Setpoint Adjustment Range.
Switch Configuration - The RTU Open generates this alarm when any two of the Unit Configuration > Input
Functions 3, 5, 8, or 9 are configured identically. Neither input may work reliably and downstream control may
be affected, depending on the function duplicated. The alarm clears and normal control is restored when the
input function duplication is corrected.
Analog Input Configuration - The RTU Open generates this alarm when the Unit Configuration > Input

RTU Open

Sequence of Operation

Functions 1 and 2 are configured identically. Neither input may work reliably and downstream control may be
affected, depending on the function duplicated. The alarm clears and normal control is restored when the
input function duplication is corrected.
High Space Relative Humidity - The RTU Open generates this alarm when the space humidity exceeds the
Alarm Configuration > High Space Humidity Alarm Limit setpoint for 10 minutes. This alarm is inhibited until
the RTU runs for 15 minutes to allow for system stabilization after startup.
Low Space Relative Humidity - The RTU Open generates this alarm when the space humidity falls below the
Alarm Configuration > Low Space Humidity Alarm Limit setpoint for 5 minutes. This alarm is inhibited until
the RTU runs for 5 minutes to allow for system stabilization after startup.
High CO2 - The RTU Open generates this alarm when the space CO2 level exceeds the Alarm Configuration >
Occupied High CO2 Alarm Limit setpoint for 1-minute. This alarm will be inhibited until the RTU has been
running for 2-minutes to allow for system stabilization after startup.
Supply Fan Runtime - The RTU Open generates a this alarm when the accumulated runtime exceeds the Unit
Configuration > Supply Fan Service Alarm Timer value (when not set to 0). This alarm is most commonly
used to indicate an equipment maintenance interval is due. The supply fan runtime accumulator may be reset
by setting the Maintenance > Reset Supply Fan Runtime Alarm to Clear, and then back to Run –
acknowledging each selection by clicking the OK button when it appears. Setting Unit Configuration > Supply
Fan Service Timer value to 0 disables the supply fan runtime alarm function.
Compressor 1 Runtime - The RTU Open generates this alarm when the accumulated runtime exceeds the
Unit Configuration > Compressor 1 Service Alarm Timer value (when not set to 0). This alarm is most
commonly used to indicate an equipment maintenance interval is due. The Compressor 1 Runtime
accumulator may be reset by setting the Maintenance > Reset Comp 1 Runtime Alarm to Clear, and then
back to Run – acknowledging each selection by clicking the OK button when it appears. Setting Unit
Configuration > Compressor 1 Service Timer value to 0 disables the Compressor 1 Runtime alarm function.
Compressor 2 Runtime - The RTU Open generates this alarm when the accumulated runtime exceeds the
Unit Configuration > Compressor 2 Service Alarm Timer value (when not set to 0). This alarm is most
commonly used to indicate an equipment maintenance interval is due. The Compressor 2 runtime
accumulator may be reset by setting the Maintenance > Reset Comp 2 Runtime Alarm to Clear, and then
back to Run – acknowledging each selection by clicking the OK button when it appears. Setting Unit
Configuration > Compressor 2 Service Timer value to 0 disables the Compressor 2 runtime alarm function.
Note that this function is unavailable if the Service Configuration > Compressor States value is not set to Two
Stages.
Filter - The RTU Open generates this alarm when the accumulated runtime exceeds the Unit Configuration >
Filter Service Alarm Timer value (when not set to 0). This alarm is most commonly used to indicate a filter
replacement is due. Reset the filter service runtime accumulator by setting the Maintenance > Reset Filter
Runtime Alarm to On, back to Off, and clicking the OK button after each setting. Setting Unit Configuration >
Filter Service Alarm Timer value to 0 disables the filter service alarm function.
Airside Linkage Alarm - An RTU Open may act as an air source in a zoned system. Carrier systems utilize a
function called Linkage™ to pass data between a master zone and its air source via an MS/TP network
connection. When the RTU Open is part of a linked system, it will indicate an airside linkage alarm if it loses
communications with its linkage master or if it receives invalid data.

RTU Open

Linkage
The RTU Open may serve as an air source to an Open Variable Volume Terminal (VVT) system. When the RTU
Open is part of a VVT system and the controllers are wired together to form a network, the controllers may use
a method of communication known as Linkage™. Linkage is a method by which an air source and its
subordinate zone terminals exchange data to form a coordinated HVAC system. The system's air source
controller, zone controllers, and bypass controller are linked so that their data exchange can be managed by
one zone controller configured as the VVT Master.
The VVT Master gathers the following information from the slave zone controllers:
•

occupancy status

•

setpoints

•

zone temperature

•

relative humidity

•

CO2 level

•

damper position

•

optimal start data

The VVT Master performs mathematical calculations and algorithms on the data and then sends the
composite information to the air source. The VVT Master receives information from the air source such as
mode, supply air temperature, and outside air temperature, and passes that information to all linked
controllers.
NOTE The following paragraphs describe the interaction between the air source (RTU Open) and its
subordinate zones. Additional information regarding Open Zoned Systems may be found in the VVT Zone and
VVT Bypass Controller Installation Guides.
The VVT Master determines system operation by prioritizing heating and cooling requirements from all the
zones based on their occupancy and demand. The VVT Master scans the system continuously to determine if
any zones are occupied. Occupied zones are a higher priority than unoccupied zones. The VVT Master
evaluates all the occupied zones' heating or cooling demands and sends a request to the air source (RTU
Open) for:
•

Cooling, if the number of occupied zones with cooling demands exceeds the number of occupied zones
with heating demands, and the demand is greater than or equal to the number of configured Linkage
Callers.
•
Heating, if the number of occupied zones with a heating demand exceeds or is equal to the number of
Linkage Callers.
If no zones are occupied or no occupied zones require heating or cooling, the VVT Master performs the
evaluation described above for the unoccupied zones.
The VVT Master then gathers the following information and sends it to the air source (RTU Open):
•
•

The system mode
The setpoints and zone temperature from the zone with the greatest demand for the requested air
source mode (heating or cooling). (This zone is called the reference zone.)
•
The system occupancy status
•
Most open damper position from any zone
•
RH and CO2 values (if applicable)
The air source responds by sending the air source mode, supply air temperature, and outside air temperature.
The air source verifies the mode by comparing its supply air temperature to the space temperature received
through Linkage. See the air source documentation for operation and parameters used to verify its mode.
This verification allows the VVT system to determine if the desired air source mode is actually being provided.
For example, if the VVT Master sends a request for heating and the air source does not have heat or it’s heat
has failed, the air source's actual mode indicates that and it's current mode is sent to the zones so that they
can control accordingly.

RTU Open

Sequence of Operation

The system remains in that mode until all zones of that demand are satisfied or until a fixed 30 minute mode
reselect timer causes a forced re-evaluation of the system. If there is no demand for the opposite mode, the
reselect timer starts again and the current mode continues until all zones are satisfied or until the reselect
timer expires, repeating the process. If there is a demand for the opposite mode, the VVT Master sends the
reference zone's space temperature and setpoints to the air source and restarts the reselect timer. The air
source re-evaluates its demand based on the new information and goes to the Vent mode until the new mode
can be verified as described above. The amount of time this takes is determined by the air source’s operating
parameters.
The VVT Master continuously evaluates the system and updates the air source with the most current system
demand. Based on the evaluation, the reference zone can change from one zone to another. The evaluation
process continues until there is no demand from any zone or the 30 minute timer causes a re-evaluation of
the system conditions.
If no heating or cooling is required or the current air source mode is satisfied, the VVT Master calculates the
weighted average of the occupied and unoccupied heating and cooling setpoints. It also calculates a zone
temperature that is midway between the setpoints (occupied or unoccupied based on the system’s current
occupancy status). This information, plus the occupancy status, is sent to the air source so that its current
mode is disabled and the unit ceases heating or cooling operation. If the system is occupied, the air source
fan and OA damper, if applicable, operate to maintain proper ventilation.

Linkage Air Source Modes
In a linked system, the air source determines its operating mode and qualifies that mode based on its own
Supply Air Temperature (SAT). The following modes can be sent by the air source depending on its
configuration:

•

Off – Air source fan is off

•

Fan Only – Air source fan is on and providing ventilation (neutral SAT) without heating or cooling

•

Economizer Cooling – Air source fan is on and providing cooling, using economizer only

•

Cooling – Air source fan is on and cooling is provided by economizer and mechanical cooling

•

Heating – Air source fan is on and heating is provided (gas or electric)

•

Dehumidification – Air source fan is on and Humidi-MiZer™ is active

•

Test – The RTU Open Service Test mode is active

•

Shutdown – Air source fan is off due to Safety Chain, Fire Shutdown, or invalid SAT sensor

•

Unocc Free Cooling – Air source fan is on, with the economizer providing cooling while unoccupied

RTU Open

Troubleshooting
If you have problems mounting, wiring, or addressing the RTU Open, contact Carrier Control Systems Support.

Serial number
If you need the RTU Open's serial number when troubleshooting, the number is on:
•
•

a sticker on the back of the main controller board
a Module Status report (modstat) from your user interface

LED's
The LED's on the RTU Open show the status of certain functions.
If this LED is on...

Status is...

Power

The RTU Open has power

The RTU Open is receiving data from the network segment

The RTU Open is transmitting data over the network segment

DO#

The binary output is active

The Run and Error LED's indicate controller and network status.

RTU Open

If Run LED shows...

And Error LED shows...

Status is..

2 flashes per second

Off

Normal

2 flashes per second

2 flashes,
alternating with Run LED

Five minute auto-restart delay
after system error

2 flashes per second

3 flashes, then off

The controller has just been
formatted

2 flashes per second

Exec halted after frequent system
errors or control programs halted

5 flashes per second

Off

Firmware transfer in progress,
Boot is running

7 flashes per second

7 flashes per second,
alternating with Run LED

Ten second recovery period after
brownout

Troubleshooting

If Run LED shows...

And Error LED shows...

Status is..

14 flashes per second

14 flashes per second,
alternating with Run LED

Brownout

Failure. Try the following solutions:
•

Turn the RTU Open off, then
on.

•

Format the RTU Open.*

•

Download memory to the RTU
Open.

•

Replace the RTU Open.

*Formatting the controller may result in lost information and should only be done under the guidance of
Carrier Control Systems Support.

Replacing the RTU Open's battery
The RTU Open's 10-year Lithium CR2032 battery provides a minimum of 10,000 hours of data retention
during power outages.
CAUTION Power must be ON to the RTU Open when replacing the battery, or your date, time, and trend data
will be lost.

Remove the battery from the controller, making note of the battery's polarity.

Insert the new battery, matching the battery's polarity with the polarity indicated on the RTU Open.

RTU Open

Compliance
FCC Compliance
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference when the equipment is operated in a commercial environment. This equipment generates, uses,
and can radiate radio frequency energy and, if not installed and used in accordance with the instruction
manual, may cause harmful interference to radio communications. Operation of this equipment in a
residential area is likely to cause harmful interference in which case the user will be required to correct the
interference at his own expense.
CAUTION Changes or modifications not expressly approved by the responsible party for compliance could
void the user’s authority to operate the equipment.

CE Compliance
WARNING This is a Class A product. In a domestic environment, this product may cause radio interference in
which case the user may be required to take adequate measures.

BACnet Compliance
BACnet® is a registered trademark of ASHRAE. ASHRAE does not endorse, approve or test products for
compliance with ASHRAE standards. Compliance of listed products to requirements of ASHRAE Standard 135
is the responsibility of the BACnet manufacturers Association (BMA). BTL® is a registered trademark of the
BMA.

RTU Open

Appendix A: RTU Open Points/Properties

Appendix A: RTU Open Points/Properties
Status
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Status
HOME > STATUS

Point Name/Description

Range

System Mode – The controller's current operating status.

Disabled
Test
Run

Operating Mode – The controller's current operating mode.

Off
Fan Only
Economizer
Cooling
Heating
Dehumidification
Test
Shutdown
Unocc Free Cooling (NTFC)

Supply Fan Status – The current fan status if an input is configured for Fan Status.

Off/Running

Space Temperature - Prime Variable – The space temperature value currently used for
control.

-56 to 245°F

Supply Air Temperature – The current supply air temperature.

-56 to 245°F

Outdoor Air Temperature – The outdoor air temperature value used for control.

-56 to 245°F

Space Relative Humidity – The current space relative humidity if Configuration > Unit
Configuration > Input 1 (or 2) Function is set to Space RH Sensor.

0 to 100%rh

Indoor Air CO2 – The current indoor air CO 2 concentration if the Configuration >Unit
Configuration > Input 1 (or 2) Function is set to IAQ Sensor.

0 to 5000ppm

Outdoor Air CO2 – The current outdoor air CO 2 concentration if the Configuration >Unit
Configuration >Input 1 (or 2) Function is set to OAQ Sensor.

0 to 5000ppm

Economizer Output – The current economizer output with respect to the outdoor air
damper (if equipped).

0 to 100% Open

RTU Open

Unit Configuration
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Unit Configuration
HOME > CONFIG > UNIT

Point Name/Description

Default/Range

Fan Mode – The supply fan's operating mode.

Continuous

Auto
Continuous
Always On

Unit Start Delay – The amount of time the controller delays starting up after receiving a
start command.

5 sec

0 to 30 sec

Fan Off Delay – How long the supply fan runs after receiving a valid stop command.

90 sec

0 to 180 sec

50°F

45 to 75°F

120°F

85 to 150°F

50% Open

0 to 100% Open

DCV Max Vent Damper Pos – The maximum outdoor air damper position allowed while
DCV is active.

50% Open

10 to 60% Open

Supply Fan Service Alarm Timer – A Supply Fan Runtime alarm is generated when the
supply fan run hours exceed this value. Set to 0 to disable.

600 hr

0 to 9999 hr

0 hr

0 to 9999 hr

0 hr

0 to 9999 hr

Filter Service Alarm Timer – The amount of time the fan will run before generating a
Filter Alarm. Set to 0 to disable the alarm and reset accumulated fan hours.

600 hr

0 to 9999 hr

Pushbutton Override – Enables or disables the use of a pushbutton override from a local
space temperature sensor.

Enable

Disable/Enable

45°F

0 to 80°F

75°F

55 to 80°F

Minimum Cooling SAT – In cooling mode, the cooling outputs are controlled so that the
supply air temperature does not drop below this value.
Maximum Heating SAT – In heating mode, the heating outputs are controlled so the
supply air temperature does not rise above this value.
Vent Dmpr Pos / DCV Min Pos – The minimum outdoor air damper position maintained
during occupied periods.

Compressor 1 Service Alarm Timer – A Compressor 1 Runtime alarm is generated when
the compressor 1 run hours exceed this value. Set to 0 to disable.
Compressor 2 Service Alarm Timer – A Compressor 2 Runtime alarm is generated when
the compressor 2 run hours exceed this value. Set to 0 to disable.

Cooling Lockout Temp – The outdoor air temperature at which cooling is inhibited.
Economizer High OAT Lockout – The outdoor air temperature at which economizer
cooling is inhibited.

RTU Open

Appendix A: RTU Open Points/Properties

Point Name/Description

Default/Range

HP Rev Cycle Lockout Temp – The outdoor air temperature at which reverse cycle
heating is locked out. Requires that the unit is configured as a Heat Pump.

-3°F

-20 to 30°F

65°F

35 to 150°F

Unocc Free Cool Enable – Enable to allow the unit to use economizer to provide
unoccupied free cooling (NTFC).

Disable

Disable/Enable

Occupancy Source - The method that the controller uses to determine occupancy.

Always Occupied

Always Occupied
BACnet Schedule
BAS On/Off
Remote Occ Input

No Sensor

No Sensor
IAQ Sensor
OAQ Sensor
Space RH Sensor

No Sensor

No Sensor
IAQ Sensor
OAQ Sensor
Space RH Sensor

Input 3 Function – The usage of Input 3. You must also set Input 3 Switch Configuration.

Compressor Safety

No Function
Compressor Safety
Fan Status
Filter Status
Remote Occupancy
Door Contact

Input 3 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

Input 5 Function – The usage of Input 5. You must also set Input 5 Switch Configuration.

Fire Shutdown

No Function
Fire Shutdown
Fan Status
Filter Status
Remote Occupancy
Door Contact

Input 5 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

Heating Lockout Temperature – The outdoor air temperature at which heating is
inhibited.

Input Configuration
Input 1 Function – The type of sensor (4-20 mA) connected to terminals J4 – 4, 5, & 6.

Input 2 Function – The type of sensor (4-20 mA) connected to terminals J4 – 1, 2, & 3.

RTU Open

Point Name/Description

Default/Range

Input 8 Function – The usage of Input 8. You must also set Input 8 Switch Configuration.

Enthalpy Switch

No Function
Enthalpy Switch
Fan Status
Filter Status
Remote Occupancy
Door Contact

Input 8 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

Input 9 Function – The usage of Input 9. You must also set Input 9 Switch Configuration.

Humidistat

No Function
Humidistat
Fan Status
Filter Status
Remote Occupancy
Door Contact

Input 9 Switch Configuration – The normal (de-energized) state for the set of contacts
terminated at Input

NO/NC (normally
open/normally closed)

T55

T55
T56 (Use for T59)
SPT Sensor
None

1 hr

0 to 24 hours

0°F

-9.9 to 10°F

Supply Air Temp Calibration – A calibration offset value to allow the supply air
temperature sensor to be adjusted to match a calibrated standard measuring the
temperature in the same location.

0°F

-9.9 to 10°F

Outside Air Temp Calibration – A calibration offset value to allow the outside air
temperature sensor to be adjusted to match a calibrated standard measuring the
temperature in the same location.

0°F

-9.9 to 10°F

Space sensor type - The type of local space temperature sensor.

T5x Override Duration – If using a T55, T56, or T59 sensor, this is the amount of time
that the controller runs in the occupied mode when a user presses the sensor's override
button for 1 to 10 seconds.
Sensor Calibration
Space Temp Calibration – A calibration offset value to allow the local space temperature
sensor to be adjusted to match a calibrated standard measuring the temperature in the
same location.

Setpoints

RTU Open

Appendix A: RTU Open Points/Properties

Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Setpoints
HOME > CONFIG > SETPOINT

Select a color band on the setpoint graph to see the current setpoints in the Heating and Cooling fields. See setpoint
descriptions below.

Occupied Setpoints
The occupied setpoints described below are the setpoints under normal operating conditions. The Demand Level 1–3
setpoints apply if demand limiting is used.
Demand limiting is a cost-saving strategy to reduce energy consumption. The strategy expands the occupied heating and
cooling setpoints when the system reaches one of 3 levels of consumption. With the expanded setpoints, the equipment
works less, thereby saving energy. By default, Demand Level 1 expands the occupied heating and cooling setpoints by 1°F,
Demand Level 2 by 2°F, and Demand Level 3 by 4°F. If the occupied heating or cooling setpoints change, the (effective)
demand level setpoints automatically change by the same amount. See Sequence of Operation (page 42) for more
information.
Default
Range: -40 to 245°F
Demand Level
Point Name/Description

Occupied

Occupied Heating – Green
The heating setpoint the controller maintains while in occupied mode.

70°F

69°F

68°F

66°F

Occupied Cooling – Green
The cooling setpoint the controller maintains while in occupied mode.

74°F

75°F

76°F

78°F

Occupied Heating 1 – Light Blue
The space temperature must be less than the Occupied Heating 1 setpoint for the
VVT Master to consider the zone a heating caller in a linked system. In a singlezone application, the heating requirement begins as soon as the space
temperature falls below the Occupied Heating setpoint. We recommend that the
Occupied Heating 1 value be set no less than 0.5°F below the Occupied Heating
setpoint.

69°F

68°F

67°F

65°F

Occupied Heating 2 – Dark Blue
68°F
The space temperature must be less than the Occupied Heating 2 setpoint to
generate a low space temperature alarm. We recommend that this value be set no
less than 0.5°F below the Occupied Heating 1 setpoint.

67°F

66°F

64°F

RTU Open

Default
Range: -40 to 245°F
Demand Level
Point Name/Description

Occupied

Occupied Cooling 1 – Yellow
75°F
The space temperature must be greater than the Occupied Cooling 1 setpoint for
the VVT Master to consider the zone a cooling caller in a linked system. In a singlezone application, the cooling requirement begins as soon as the space
temperature exceeds the Occupied Cooling setpoint. We recommend that the
Occupied Cooling 1 value be set no less than 0.5°F above the Occupied Cooling
setpoint.

76°F

77°F

79°F

Occupied Cooling 2 – Orange
The space temperature must be greater than the Occupied Cooling 2 setpoint to
generate a high space temperature alarm. We recommend that this value be set
no less than 0.5°F above the Occupied Cooling 1 setpoint.

78°F

81°F

76°F

Unoccupied Setpoints
Point Name/Description

Default/Range

Unoccupied Heating – Gray
The heating setpoint the controller maintains while in unoccupied mode.

55°F

45 to 100°F

90°F

-40 to 245°F

Unoccupied Cooling – Gray
The cooling setpoint the controller maintains while in unoccupied mode.

Unoccupied Heating 1 – Light Blue
D:
The space temperature must be less than the Unoccupied Heating 1 setpoint for the VVT
R:
Master to consider the zone an unoccupied heating caller in a linked system. In a single-zone
application, the unoccupied heating requirement begins as soon as the space temperature falls
below the Unoccupied Heating setpoint. We recommend that the Unoccupied Heating 1 value
be set no less than 0.5°F below the Unoccupied Heating setpoint.

54°F

Unoccupied Heating 2 – Dark Blue
The space temperature must be less than the Unoccupied Heating 2 setpoint to generate an
unoccupied low space temperature alarm. We recommend that this value be set no less than
0.5°F below the Unoccupied Heating 1 setpoint.

52°F

-40 to 245°F

Unoccupied Cooling 1 – Yellow
D:
The space temperature must be greater than the Unoccupied Cooling 1 setpoint for the VVT
R:
Master to consider the zone an unoccupied cooling caller in a linked system. In a single-zone
application, the unoccupied cooling requirement begins as soon as the space temperature
exceeds the Unoccupied Cooling setpoint. We recommend that the Unoccupied Cooling 1 value
be set no less than 0.5°F above the Unoccupied Cooling setpoint.

91°F

Unoccupied Cooling 2 – Orange
D:
The space temperature must be greater than the Unoccupied Cooling 2 setpoint to generate an
R:
unoccupied high space temperature alarm. We recommend that this value be set no less than
0.5°F above the Unoccupied Cooling 1 setpoint.

93°F

RTU Open

-40 to 245°F

Appendix A: RTU Open Points/Properties

Point Name/Description

Default/Range

Heating Capacity – Used for Optimal Start, this is the rate at which the zone temperature
changes when the heating system runs at full capacity to maintain designed occupied heating
setpoint.

5°F/hr

0 to 120°F/hr

0°F

-100 to 150°F

Cooling Capacity – Used for Optimal Start, this is the rate at which the zone temperature
changes when cooling system runs at full capacity to maintain designed occupied cooling
setpoint.

5°F/hr

0 to 140°F/hr

Cooling Design Temp – The geographically-based outdoor air temperature at which the cooling
system must run constantly to maintain comfort. This information is available in ASHRAE
publications and most design references.

100°F

-100 to 150°F

0.5°F

0 to 120°F

Heating Design Temp – The geographically-based outdoor air temperature at which the heating
system must run constantly to maintain comfort. This information is available in ASHRAE
publications and most design references.

Hysteresis – The desired difference between the temperature at which the zone color changes
as the zone temperature departs from the acceptable range between the heating and cooling
setpoints (green) into the Cooling 1 (yellow) or Heating 1 (light blue) and the temperature at
which the zone color changes back to the acceptable range between the heating and cooling
setpoints.
For example, the following graph shows the zone color that results as the zone temperature
departs from and returns to the acceptable range in a zone with the following settings:
•
•
•

Color Change Hysteresis = .5° (applies as the temperature returns to the acceptable
range)
Occupied cooling setpoint = 76°
Occupied heating setpoint = 70°
Temp

Occupied cooling setpoint: 76°
75.5°

.5° hysteresis

70.5°
Occupied heating setpoint: 70°

.5° hysteresis
Time

Effective Setpoints

The Effective Setpoints graph shows the current occupied or unoccupied setpoints. If occupied, these values are the current
programmed setpoints plus the offset of any setpoint adjustment that may be in affect. If unoccupied, the values are the
programmed unoccupied setpoints.

RTU Open

Point Name/Description

Default/Range

Heating – (Occupied or Unoccupied, depending on mode) The current programmed Heating
setpoint adjusted by any offset that may be in effect.

0 to 120°F

Cooling – (Occupied or Unoccupied, depending on mode) The current programmed Cooling
setpoint adjusted by any offset that may be in effect.

0 to 120°F

Optimal Start – The earliest time, prior to occupancy, at which the Optimal Start function may
begin to adjust the effective setpoints to achieve the occupied setpoints by the time scheduled
occupancy begins. Enter 0 to disable Optimal Start.

4 hr

0 to 4 hr

60%rh

0 to Unoccupied
RH Control
Setpoint

Occ Relative Humidity Setpoint – The percentage of relative humidity in the space during
occupancy that will energize BO - 6 (Humidi-MiZer™).

Unocc Relative Humidity Setpoint – The percentage of relative humidity in the space during the D:
unoccupied time period that starts the unit and energizes BO - 6 (Humidi-MiZer™).
R:

95%

DCV Max Ctrl Setpoint – The design difference between indoor and outdoor CO2 levels.

650ppm

0 to 9999 ppm

50% Open

20 to 90% Open

Power Exhaust Setpoint - The outside air damper position at which the controller energizes the
Power Exhaust relay. Configuration >Service Configuration > Economizer Exists must be set to
Yes, and Configuration >Service Configuration > Continuous Occupied Exhaust must be set to
No.

30 to 100%

Alarm Configuration
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Alarm Configuration
HOME > CONFIG > ALARMS

Point Name/Description

Default/Range

Space Temperature Alarm
Occupied Alarm Hysteresis – This value is added to the occupied high effective
setpoint and subtracted from the occupied low effective setpoint to establish the
occupied high and low limits that the space temperature must exceed before an
occupied SPT alarm is generated. The alarm returns to normal when the space
temperature drops below the high effective setpoint or rises above the low effective
setpoint.
Alarm Delay (min/deg) – Determines the amount of delay before an occupied space
temperature alarm is generated when the controller transitions to the occupied mode.
The delay time equals this value multiplied by the difference between the sensor
temperature and occupied alarm setpoint plus 15 minutes.
Unoccupied Low SPT Alarm Limit –The value that the space temperature must drop
below to generate a Space Temperature Alarm in the unoccupied mode. There is a
fixed hysteresis of 1° F for return to normal.

RTU Open

3°F

0 to 20°F

10 minutes

0 to 60 minutes

45°F

-60 to 250°F

Appendix A: RTU Open Points/Properties

Point Name/Description

Default/Range

Unoccupied High SPT Alarm Limit – The value that the space temperature must
exceed to generate a Space Temperature Alarm in the unoccupied mode. There is a
fixed hysteresis of 1° F for return to normal.

90°F

-60 to 250°F

45°F

-60 to 250°F

120°F

-60 to 250°F

Low Space Humidity Alarm Limit – The value that the relative humidity must drop
below to generate a Low Space Humidity Alarm. Requires a space relative humidity
transmitter and Configuration >Unit Configuration >Input 1 (or 2) Function set to
Space RH Sensor.

30%

0 – 99 %

High Space Humidity Alarm Limit – The value that the relative humidity must rise
above to generate a High Space Humidity Alarm. Requires a space relative humidity
transmitter and Configuration >Unit Configuration >Input 1 (or 2) Function set to
Space RH Sensor.

70%

0 – 99 %

1200ppm

0 to 9999 ppm

Supply Air Temperature Alarm
Low SAT Alarm Limit – The value that the supply air temperature must drop below to
generate a Supply Air Temp Alarm. There is a fixed hysteresis of 1° F for return to
normal.
High SAT Alarm Limit – The value that the supply air temperature must exceed to
generate a Supply Air Temp Alarm. There is a fixed hysteresis of 1° F for return to
normal.
Space Humidity Alarm

IAQ/Ventilation Alarm
Occupied High CO2 Alarm Limit – The value that the CO 2 sensor must exceed to
generate an IAQ Alarm in the occupied mode. There is a fixed hysteresis of 100ppm
for return to normal. Requires a space CO2 sensor and Configuration >Unit
Configuration >Input 1 (or 2) Function set to IAQ Sensor.

Service Configuration
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Configuration > Service Configuration
HOME > CONFIG > SERVICE

Point Name/Description

Default/Range

Unit Type – The type of equipment that the RTU Open is controlling.

Heat/Cool

Options:
Heat/Cool – Standard rooftop air handling unit.
HP O/B Ctrl – Heat Pump application, uses reversing valve output to control heating
and cooling.
HP Y1/W1 Ctrl – Carrier Heat Pump application only.

Heat/Cool
HP O/B Ctrl
HP Y1/W1 Ctrl

RTU Open

Point Name/Description

Default/Range

Compressor Stages – The number of mechanical cooling stages.

One Stage

One Stage
Two Stages

Economizer Exists – Set to Yes to enable economizer control for units equipped with
an economizer damper.

No/Yes

Heat Type – The type of heating that the unit has.

Electric

Electric/Gas

1 /2 /0 (no heating)

Continuous Occupied Exhaust – Configures the exhaust fan control strategy (BO-8). If
Yes, the power exhaust runs continuously in occupied mode and is off in unoccupied
mode. If No, the power exhaust is controlled by the Power Exhaust Setpoint.

No/Yes

Indoor CO2 Sensor Value @min (ma) – The CO2 value that corresponds to a 4mA
input at the appropriate input channel.

0ppm

0 to 9999 ppm

Indoor CO2 Sensor Value @max (ma) – The CO2 value that corresponds to a 20mA
input at the appropriate input channel.

2000 ppm

0 to 9999 ppm

Outdoor CO2 Sensor Value @min (ma) – The CO2 value that corresponds to a 4 mA
input at the appropriate input channel.

0ppm

0 to 9999 ppm

2000 ppm

0 to 9999 ppm

-999.00 °F

N/A

0.00

0-3

System Heat Demand Level – The system heat demand level being received over the
network.

0.00

0-3

System Outside Air Temperature – Allows the outside air temperature value to be
network readable when enabled. Requires that controller is equipped with an outdoor
air temperature sensor.

-999.0°F

N/A

Disable

Disable/Enable

Disable

Disable/Enable

Disable

Disable/Enable

Number Of Heat Stages – The number of heat stages.

Outdoor CO2 Sensor Value @max (ma) – The CO2 value that corresponds to a 20 mA
input at the appropriate input channel.
System Space Temperature – The network space temperature value that the
controller is using for control (if applicable).
System Cool Demand Level – The system cool demand level being received over the
network.

Service Test
Service Test – Enable to stop automatic control so you can test the controller's
outputs. Automatically resets to Disable after 1 hour.
Fan Test – Enable to test the controller's fan speeds. Sequences fan from low to high
speed and operates at each speed for 1 minute. Resets to Disable when complete.
Service Test must be set to Enable.
Compressor 1 Test – Enable to test the controller's compressor 1 output. Service
Test must be set to Enable.

RTU Open

Appendix A: RTU Open Points/Properties

Point Name/Description

Default/Range

Compressor 2 Test – Enable to test the controller's compressor 2 output. Service
Test must be set to Enable.

Disable

Disable/Enable

Heat 1 Test – Enable to test the controller's heat 1 output. Service Test must be set
to Enable.

Disable

Disable/Enable

Heat 2 Test – Enable to test the controller's heat 2 output. Service Test must be set
to Enable.

Disable

Disable/Enable

Reversing Valve Test – Enable to test the controller's reversing valve output. Service
Test must be set to Enable.

Disable

Disable/Enable

Disable

Disable/Enable

Disable

Disable/Enable

0% Open

0 to 100% Open

0 to 100%

Dehumidification Test – Enable to test the controller's humidimizer output. Service
Test must be set to Enable.
Power Exhaust Test – Enable to test the controller's exhaust fan output. Service Test
must be set to Enable.
Economizer Test – Set to a value between 0 and 100% to test the controller's
economizer output. Service Test must be set to Enable.
Analog Output 2 Test – Analog Output 2 (0-10 Vdc) is currently unused.

Maintenance
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Maintenance
HOME > MAINT

Point Name/Description

Default/Range

Unit
Occupancy Status – The controller's occupancy status as determined by a network
schedule, a local schedule, or a timed override.

Occupied/Unoccupied

Space Temp Sensor – The source of the controlling space temperature value.

Sensor Failure
SPT Sensor
T55/T56
Network
Airside Linkage
Locked Value

Off/Run Enabled

Options:
Sensor Failure – No valid space temperature or sensor status = failed.
SPT Sensor – An SPT sensor is connected to the controller’s Rnet port.
T55/56 – A T55, T56, or T59 sensor is connected to the controller’s J20 terminals.
Network – A network temperature sensor is bound to the controller’s space temperature
AV.
Airside Linkage – The space temperature from a linked terminal.
Locked Value –The controller’s space temperature input has been manually locked at a
value.
Safety Chain Feedback - Indicates a completed circuit from J1, 1 to J1, 9. This circuit is
typically used for safety devices that immediately stop unit operation when tripped.

RTU Open

Point Name/Description

Default/Range

Fire Shutdown – Shutdown indicates that a fire shutdown is in effect.

Run Enabled/
Shutdown

Compressor Safety Status – Trouble indicates that the compressor safety device has
tripped.

Normal/Trouble

Enthalpy Status – The enthalpy status determined by an enthalpy switch.

High/Low

Humidistat Input Status – The humidity status determined by a humidistat.

High/Low

Reset Supply Fan Runtime Alarm – Set to Clear to reset Supply Fan Runtime to 0.

Run

Run/Clear

Run

Run/Clear

Run

Run/Clear

Off

Off/On

Inactive

Inactive
Occupied
Unoccupied

Schedules – The controller's occupancy status based on the schedule.

Occupied/Unoccupied

Pushbutton Override – Active indicates if a user pushed the sensor's override button to
override the occupancy state.

Off/Active

Override Time Remaining – The amount of time remaining in an override period.

0 to 240 minutes

Supply Fan Runtime – The total number of hours that the supply fan relay has been
energized since the runtime was last reset to 0 using Reset Supply Fan Runtime Alarm.

___ hr

Compressor 1 Runtime – The total number of hours that the Compressor 1 relay has
been energized since the runtime was last reset 0 using Reset Comp 1 Runtime Alarm.

___ hr

Compressor 2 Runtime – The total number of hours that the Compressor 2 relay has
been energized since the runtime was last reset using Reset Comp 2 Runtime Alarm.

___ hr

Filter Runtime – The total number of hours that the unit has been operating since the
runtime was last reset to 0 using Reset Filter Runtime Alarm.

___ hr

Reset Comp 1 Runtime Alarm – Set to Clear to reset Compressor 1 Runtime to 0.
Reset Comp 2 Runtime Alarm – Set to Clear to reset Compressor 2 Runtime to 0.
Reset Filter Runtime Alarm – Set to On to reset Filter Runtime to 0.

Occupancy
BAS On/Off – Determines the occupancy state of the controller and can be set over the
network by another device or third party BAS.
Options:
Inactive – Occupancy is determined by a configured schedule.
Occupied – The controller is always in the occupied mode.
Unoccupied – The controller is always in the unoccupied mode.

Runtime

RTU Open

Appendix A: RTU Open Points/Properties

Alarms
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Alarms
HOME > ALARM

Point Name/Description

Range

Safety Chain – Indicates if the Safety Chain circuit trips.

Normal/Alarm

Fire Shutdown – Indicates if the Fire Shutdown circuit trips.

Normal/Alarm

Compressor Safety – Indicates if the Compressor Safety circuit trips.

Normal/Alarm

Space Temp Sensor – Indicates if the space temperature sensor fails.

Normal/Alarm

Supply Air Temp Sensor – Indicates if the supply air temperature sensor fails.

Normal/Alarm

Outdoor Air Temp Sensor Alarm – Indicates if the outdoor air temperature sensor fails.

Normal/Alarm

Space Relative Humidity Sensor – Indicates if the space relative humidity sensor fails.

Normal/Alarm

IAQ Sensor – Indicates if the indoor air quality (CO 2 ) sensor fails.

Normal/Alarm

OAQ Sensor – Indicates if the outdoor air quality (CO 2 ) sensor fails.

Normal/Alarm

Space Temperature – Indicates if the space temperature sensor exceeds the high or low alarm
limit.

Normal/Alarm

Alarming Temperature – The value of the alarming space temperature sensor.

The sensor's
range

Alarm Limit Exceeded – The alarm limit that the alarming space temperature sensor exceeded.

-60 to 250°F

High Supply Air Temperature – Indicates if the supply air temperature exceeds the High SAT
Alarm Limit.

Normal/Alarm

Low Supply Air Temperature – Indicates if the supply air temperature falls below the Low SAT
Alarm Limit.

Normal/Alarm

Setpoint Slider – Indicates if the T56 sensor's setpoint slider potentiometer fails.

Normal/Alarm

Switch Configuration – Indicates if a duplicate configuration exists for two or more binary Input
3, 5, 8, & 9 Functions.

Normal/Alarm

Analog Input Configuration – Indicates if a duplicate configuration exists at the analog Input 1
& 2 Functions.

Normal/Alarm

High Space Relative Humidity – Indicates if the space relative humidity exceeds the High
Space Humidity Alarm Limit.

Normal/Alarm

Low Space Relative Humidity – Indicates if the space relative humidity falls below the Low
Space Humidity Alarm Limit.

Normal/Alarm

High CO2 – Indicates if the indoor CO2 level rises above the Occupied High CO2 Alarm Limit.

Normal/Alarm

Supply Fan Runtime – Indicates if the supply fan runtime exceeds the value of the Supply Fan
Service Alarm Timer.

Normal/Alarm

Compressor 1 Runtime – Indicates if the compressor 1 runtime exceeds the value of the
Compressor 1 Service Alarm Timer.

Normal/Alarm

RTU Open

Point Name/Description

Range

Compressor 2 Runtime – Indicates if the compressor 1 runtime exceeds the value of the
Compressor 2 Service Alarm Timer.

Normal/Alarm

Filter – Indicates a dirty filter condition when the filter runtime exceeds the value of the Filter
Service Alarm Timer or in response to a filter status switch binary input.

Clean/Dirty

Airside Linkage Alarm – Indicates if Linkage fails in a zoned system using Linkage.

Normal/Alarm

Linkage
Navigation:

i-Vu / Field Assistant:
BACview:

Properties > Equipment > Linkage
Properties > Equipment > Linkage

Point Name/Description

Range

Linkage Collector – Allows access to the Collector's details.
Airside Linkage Status – If Active, the controller is part of a linked system. If Not
Active, the controller is a stand-alone device.

Active/Not Active

If Airside Linkage Status is Active, the following provide information received from
the VVT Master (as applicable):
Occupancy Status
Space Temperature
Occupied Cooling Setpoint
Occupied Heating Setpoint
Unoccupied Cooling Setpoint
Unoccupied Heating Setpoint
Indoor Air CO2
Space Relative Humidity

I/O Points
The values shown on the I/O Points Properties page are the raw values at the I/O objects and may not match
values shown on status displays that are affected by control program logic.
i-Vu users logged in as Power User and above are able to edit various parameters associated with the input
channels and the display names for all channels.
We strongly recommend that you leave these parameters at their defaults. The RTU Open is not a
programmable controller. I/O can only be used for the purpose designed in the equipment control program.
Modifying these parameters may result in unpredictable equipment control.
See Wiring inputs and outputs (page 12) for more information. This table lists each of the I/O Channels, their
functions, associated hardware, and terminal numbers.

RTU Open

Appendix A: RTU Open Points/Properties

Navigation:

i-Vu / Field Assistant:
BACview:

Properties > I/O Points
N/A

Point Name/Description
Space Temp – The value of the Optional SPT (Rnet) sensor. Also allows i-Vu & Field Assistant users access to sensor
configuration. See Carrier Sensors Installation Guide for additional details.
input 1 – Input Channel 1; 4 - 20 mA only. User-configurable for IAQ, OAQ, or Space RH.
input 2 – Input Channel 2; 4 - 20 mA only. User-configurable for IAQ, OAQ, or Space Relative Humidity.
input 6 – Input Channel 6; 10K Thermistor only. Supply Air Temperature.
input 7 – Input Channel 7; 10K Thermistor only. Outside Air Temperature.
input 10 – Input Channel 10; 10K Thermistor only. Space Temperature (T55, 56, 59).
input 11 – Input Channel 11; 100K Potentiometer only. Setpoint adjust (T56, 59).
slidepot voltage reading – Input Channel 11; used to detect an open circuit (faulty Setpoint adjustment mechanism).
input 3 – Input Channel 3; Dry Contact only. User-configurable for No Function, Compressor Safety, Fan Status, Filter
Status, Remote Occupancy, or Door Contact.
input 4 – Input Channel 4; Dry Contact only. Safety Chain.
input 5 – Input Channel 5; Dry Contact only. User-configurable for No Function, Fire Shutdown, Fan Status, Filter
Status, Remote Occupancy, or Door Contact.
input 8 – Input Channel 8; Dry Contact only. User-configurable for No Function, Enthalpy, Fan Status, Filter Status,
Remote Occupancy, or Door Contact.
input 9 – Input Channel 9; Dry Contact only. User-configurable for No Function, Humidistat, Fan Status, Filter Status,
Remote Occupancy, or Door Contact.
Sensor Invalid – Reflects the status of the Space Temp (Rnet) input. On = Space Temp invalid,
Off = Space Temp valid.
ao 1 – Analog Output Channel 1; jumper selectable.
ao 2 – Analog Output Channel 2; 0 - 10 Vdc. Not Utilized.
relay 1 – Binary Output 1; Fan (G) Output.
relay 2 – Binary Output 2; Heat 2 (W2) Output.
relay 3 – Binary Output 3; Heat 1 (W1) Output.
relay 4 – Binary Output 4; Cool 2 (Y2) Output.
relay 5 – Binary Output 5; Cool 1 (Y1) Output.
relay 6 – Binary Output 6; Humidi-MiZer ™ Output.
relay 7 – Binary Output 7; Reversing Valve Output.
relay 8 – Binary Output 8; Power Exhaust Output.

RTU Open

Appendix B: Single Point Linkage and Device Address Binding
Single Point Linkage
The RTU Open receives data from other Open controllers when they are installed as part of an Open system.
The data transfer may take the form of Single Point Linkage (SPL), which is automatic, or Device Address
Binding, which you must configure.
Currently, the RTU Open implements Single Point Linkage for 3 variables: Refer to configuration section complete list - make list to system system configuration1.....might be different for RTU - might be unit config
•

System Cool Demand Level

•

System Heat Demand Level

•

System Outside Air Temperature

Network Points for which SPL has been implemented are displayed in i-Vu and Field Assistant on the
Properties page > Network Points tab.
The following example involves outside air temperature. System Heat & Cool Demand Level behaves
similarly, except that their usage involves a specific application loaded on a Universal Controller Open. See UC
Open Installation Guide for additional information. In either case, note that the BACnet type and instance
numbers specified in the Address field of these variables have been predefined.
Network variables for which SPL is used are easily identified on the Properties page > Network Points tab.
The asterisk in the BACnet address invokes the SPL function. These addresses cause the controller to issue a
BACnet “who has” command for this variable. The controller binds to the closest of the first five devices from
which it receives a valid response.

RTU Open

Appendix B: Single Point Linkage and Device Address Binding

Device Address Binding
As described previously, Device Address Binding allows the RTU Open to receive data from other Open
controllers when they are connected by a network. You must configure this method.
Currently, the RTU Open allows Device Address Binding (DAB) only for System Space Temperature.
Network Points on which DAB may be implemented are displayed in i-Vu and Field Assistant on the Properties
page > Network Points tab with an undefined BACnet address.

RTU Open

Index

Index
B
BACnet compliance • 57
BACnet port • 11
BT485 • 10

C
Compliance • 57

D
Duct Air Temperature sensor • 22
Duct sensors
Duct Air Temperature sensor • 22
Supply Air Temperature sensor • 21

F
FCC compliance • 57
Field Assistant • 58

I
i-Vu • 58

L
Linkage • 73

M
Module Status report • 55
MS/TP network, wiring • 10

P
Points/Properties • 58
Airside Linkage Alarm • 70
Airside Linkage Status • 71
Alarm Delay (min/deg) • 65
Alarm Limit Exceeded • 70
Alarming Temperature • 70
Analog Input Configuration • 70
Analog Output 2 Test • 65
BAS On/Off • 68
Compressor 1 Runtime • 68
Compressor 1 Runtime alarm • 70
Compressor 1 Service Alarm Timer • 59
Compressor 1 Test • 66
Compressor 2 Runtime • 68
Compressor 2 Runtime alarm • 70
Compressor 2 Service Alarm Timer • 59
Compressor 2 Test • 66
Compressor Safety alarm • 70
Compressor Safety Status • 68
Compressor Stages • 40, 66
Continuous Occupied Exhaust • 40, 66
Cooling Capacity • 61
Cooling Design Temp • 61
Cooling Lockout Temp • 59
DCV Max Ctrl Setpoint • 39, 59
RTU Open

DCV Max Vent Damper Pos • 59
Dehumidification Test • 66
Economizer Exists • 40, 66
Economizer High OAT Lockout • 59
Economizer Output • 58
Economizer Test • 66
Enthalpy Status • 68
Fan Mode • 37, 59
Fan Off Delay • 59
Fan Test • 66
Filter Alarm • 70
Filter Runtime • 68
Filter Service Alarm Timer • 59
Fire Shutdown • 68
Fire Shutdown alarm • 70
Heat 1 Test • 66
Heat 2 Test • 66
Heat Type • 40, 66
Heating Capacity • 61
Heating Design Temp • 61
Heating Lockout Temperature • 59
High CO2 alarm • 70
High SAT Alarm Limit • 65
High Space Humidity Alarm Limit • 65
High Space Relative Humidity alarm • 70
High Supply Air Temperature alarm • 70
HP Rev Cycle Lockout Temmp • 59
Humidistat Input Status • 68
Hysteresis • 61
IAQ Sensor alarm • 70
Indoor Air CO2 • 58, 71
Indoor CO2 Sensor Value @max (ma) • 40, 66
Indoor CO2 Sensor Value @min (ma) • 40, 66
Input # Function • 37, 59
Input # Switch Configuration • 37, 59
LAT Airflow Increase • 58
Linkage Collector • 71
Low SAT Alarm Limit • 65
Low Space Humidity Alarm Limit • 65
Low Space Relative Humidity alarm • 70
Low Supply Air Temperature alarm • 70
Maximum Heating SAT • 59
Minimum Cooling SAT • 59
Number of Heat Stages • 40, 66
OAQ Sensor alarm • 70
OAT System Sensor • 66
Occ Relative Humidity Setpoint • 39, 61
Occupancy Source • 37, 59
Occupancy Status • 68, 71
Occupied Alarm Hysteresis • 65
Occupied Cooling • 39, 61
Occupied Cooling 1 • 61
Occupied Cooling 2 • 61
Occupied Cooling Setpoint • 71
Occupied Heating • 39, 61
Occupied Heating 1 • 61
Occupied Heating 2 • 61
Occupied Heating Setpoint • 71
Occupied High CO2 Alarm Limit • 65
75

Index

Operating Mode • 58
Optimal Start • 39, 61
Outdoor Air CO2 • 58
Outdoor Air Temp Sensor Alarm • 70
Outdoor Air Temperature • 58
Outdoor CO2 Sensor Value @max (ma) • 40, 66
Outdoor CO2 Sensor Value @min (ma) • 40, 66
Outside Air Temp Calibration • 59
Override Time Remaining • 68
Power Exhaust Setpoint • 39, 61
Power Exhaust Test • 66
Pushbutton Override • 59, 68
Reset Comp 1 Runtime Alarm • 68
Reset Comp 2 Runtime Alarm • 68
Reset Filter Runtime Alarm • 68
Reset Supply Fan Runtime Alarm • 68
Reversing Valve Test • 66
Safety Chain alarm • 70
Safety Chain Feedback • 68
Schedules • 68
Service Test • 66
Setpoint Slider • 70
Space Relative Humidity • 58, 71
Space Relative Humidity Sensor alarm • 70
Space sensor type • 37, 59
Space Temp Calibration • 59
Space Temp Sensor • 70
Space Temp Sensor Alarm • 70
Space Temperature • 71
Space Temperature - Prime Variable • 58
Space Temperature Alarm • 70
Supply Air Temp Calibration • 59
Supply Air Temp Sensor alarm • 70
Supply Air Temperature • 58
Supply Fan Runtime • 68
Supply Fan Runtime alarm • 70
Supply Fan Service Alarm Timer • 59
Supply Fan Status • 58
Switch Configuration • 70
System Cool Demand Level • 66
System Heat Demand Level • 66
System Mode • 58
System Outside Air Temperature • 66
System Space Temperature • 66
T5x Override Duration • 59
Unit Start Delay • 59
Unit Type • 40, 66
Unocc Free Cool Enable • 59
Unocc Relative Humidity Setpoint • 39, 61
Unoccupied Cooling • 39, 61
Unoccupied Cooling 1 • 61
Unoccupied Cooling 2 • 61
Unoccupied Cooling Setpoint • 71
Unoccupied Heating • 39, 61
Unoccupied Heating 1 • 61
Unoccupied Heating 2 • 61
Unoccupied Heating Setpoint • 71
Unoccupied High SPT Alarm Limit • 65
Unoccupied Low SPT Alarm Limit • 65
Vent Dmpr Pos / DCV Min Pos • 59

Rnet wiring specifications • 20

S
Serial number • 55
SPT sensors • 20
Supply Air Temperature sensor • 21

T
temperature sensors
Duct Air Temperature sensor • 22
SPT sensors • 20
Supply Air Temperature sensor • 21
Troubleshooting • 55

W
Wiring specifications
Network • 11
Rnet • 20

R
Rnet • 20
76

RTU Open

CARRIER CORPORATION ©2010
A member of the United Technologies Corporation family · Stock symbol UTX · Catalog No. 11-808-427-01 · 11/19/2010

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