A7 Error Code Troubleshooting Bosch
User Manual: A7 error code troubleshooting-Bosch
Open the PDF directly: View PDF 
.
Page Count: 2
| Download | |
| Open PDF In Browser | View PDF |
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html Service Bulletin: TWH-G2-31 Model: 250SX, 250SXO, 635ES, 635ESO, 2400E, 2400EO A7 Error Code Troubleshooting Introduction Figure 1 Follow the procedures below and report results to Bosch Technical Support. This will assist in determining the cause and solution to the problem. An A7 error indicates a problem related to the outlet hot water temperature sensor. The sensor may be sensing temperatures outside normal parameters or the sensor itself may be defective. NTC Temperature Sensors • The sensor is a negative temperature coefficient (NTC) sensor that reads different temperatures based on different resistances. • Lower resistances are interpreted as higher temperatures; higher resistances are interpreted as lower temperatures. • See Bulletin TWH-G2-05 for approximate temperature sensor resistance readings Tools needed: • Ohmmeter/ multimeter • Phillips head screwdriver • Fine sandpaper or emery cloth Procedure 1. Press the reset button on the control panel of the heater to attempt to clear the error code. If the error code does not reset or continues to reoccur, proceed with the following troubleshooting steps. 2. Verify the heater is being used for domestic hot water only and is not being fed any preheated water. 3. Verify the heater is not installed in a location that may be exposed to freezing temperatures. 4. Remove the front cover of the water heater. For instructions on removing the front cover, refer to the installation/owner’s manual of the water heater. 5. Locate the hot water temperature sensor on the 1/2” copper pipe inside the lower left side of the water heater. The hot water temperature sensor is connected with two red wires and should be clipped to the horizontal section of the hot water pipe. See Figure 1. Hot sensor Cold sensor 6. Inspect the hot water temperature sensor: a. Sensor should be positioned on the top of the horizontal section of the hot water pipe. b. The sensor should not be positioned on an elbow or near the bypass tube on the vertical section of the hot water pipe. c. Unclip the sensor from the copper pipe and inspect the inside of the sensor. Sensor should be clean and free of corrosion. d. Sensor spade connections (red wires) must be clean and tight. e. If wire connections, sensor, or pipe are corroded, clean with fine sandpaper or emery cloth. f. If cleaning and repositioning the sensor fail to fix the error, the sensor may need to be replaced. 7. The inlet cold water sensor and the outlet hot water sensor are identical. As a test, swap the hot and cold sensors. a. Turn off the heater and disconnect both the cold and the hot water sensors from the pipes. b. Disconnect the blue wires from the cold water sensor. c. Disconnect the red wires from the hot water sensor. d. Swap the sensors, placing the cold water sensor on the hot water side and vice versa, and reattach the wires to each sensor. (Swap the sensors only, not the wires.) e. After swapping the sensors, turn the heater on and try resetting any error codes that that are displayed. If the error has now changed from A7 to E2, the error is following the sensor, indicating the sensor is likely defective and will need to be replaced. (Part # 8700400015.) f. If the E2 error continues after swapping the sensors and resetting the error code, there may be a problem with the wiring harness or control board. Contact Bosch Tech Support. | TWH-G2-31 | 250SX, 250SXO, 635ES, 635ESO, 2400E, 2400EO Service bulletin 8. For an alternate test to check the sensors with a multimeter, refer to Bulletin TWH-G2-05 for testing procedure. Bosch Thermotechnology Corp. 50 Wentworth Avenue Londonderry, NH 03053 Tel: 1-866-642-3198 Fax: 1-603-584-1681 www.boschpro.com Data subject to change without notice | Printed in the USA | BTC 711002311 A | 01.2010 Bosch Thermotechnology Corp.
Source Exif Data:
File Type : PDF File Type Extension : pdf MIME Type : application/pdf PDF Version : 1.4 Linearized : No Warning : Invalid secondary xref table Tagged PDF : Yes XMP Toolkit : Adobe XMP Core 4.2.2-c063 53.352624, 2008/07/30-18:12:18 Create Date : 2010:01:19 16:43:59-05:00 Metadata Date : 2010:01:19 16:44:01-05:00 Modify Date : 2010:01:19 16:44:01-05:00 Creator Tool : Adobe InDesign CS4 (6.0.4) Thumbnail Format : JPEG Thumbnail Width : 256 Thumbnail Height : 256 Thumbnail Image : (Binary data 11409 bytes, use -b option to extract) Instance ID : uuid:81ebc492-765d-4a4b-9b9c-34bf1148d957 Document ID : xmp.did:28F3B5001F05DF11B189A339CCF7D81E Original Document ID : adobe:docid:indd:791fbe93-c146-11dd-aa14-dbc4f1d95588 Rendition Class : proof:pdf Derived From Instance ID : xmp.iid:27F3B5001F05DF11B189A339CCF7D81E Derived From Document ID : xmp.did:D4BB10CDA486DE118F20F93C13DB515B Derived From Original Document ID: adobe:docid:indd:791fbe93-c146-11dd-aa14-dbc4f1d95588 Derived From Rendition Class : default History Action : saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved, saved History Instance ID : xmp.iid:CEBB10CDA486DE118F20F93C13DB515B, xmp.iid:CFBB10CDA486DE118F20F93C13DB515B, xmp.iid:D0BB10CDA486DE118F20F93C13DB515B, xmp.iid:D1BB10CDA486DE118F20F93C13DB515B, xmp.iid:D2BB10CDA486DE118F20F93C13DB515B, xmp.iid:D3BB10CDA486DE118F20F93C13DB515B, xmp.iid:D4BB10CDA486DE118F20F93C13DB515B, xmp.iid:D5BB10CDA486DE118F20F93C13DB515B, xmp.iid:D6BB10CDA486DE118F20F93C13DB515B, xmp.iid:D7BB10CDA486DE118F20F93C13DB515B, xmp.iid:FF4A4DF65A96DE1187629AB738F7C057, xmp.iid:004B4DF65A96DE1187629AB738F7C057, xmp.iid:7A5B683F26ACDE11B19BD285E0BD97BE, xmp.iid:00D17E370505DF1182D7ADD808087F87, xmp.iid:1FF3B5001F05DF11B189A339CCF7D81E, xmp.iid:20F3B5001F05DF11B189A339CCF7D81E, xmp.iid:21F3B5001F05DF11B189A339CCF7D81E, xmp.iid:22F3B5001F05DF11B189A339CCF7D81E, xmp.iid:23F3B5001F05DF11B189A339CCF7D81E, xmp.iid:24F3B5001F05DF11B189A339CCF7D81E, xmp.iid:25F3B5001F05DF11B189A339CCF7D81E, xmp.iid:26F3B5001F05DF11B189A339CCF7D81E, xmp.iid:27F3B5001F05DF11B189A339CCF7D81E, xmp.iid:28F3B5001F05DF11B189A339CCF7D81E, xmp.iid:731633A93F05DF11B189A339CCF7D81E, xmp.iid:741633A93F05DF11B189A339CCF7D81E, xmp.iid:751633A93F05DF11B189A339CCF7D81E, xmp.iid:761633A93F05DF11B189A339CCF7D81E, xmp.iid:771633A93F05DF11B189A339CCF7D81E History When : 2009:08:11 14:28:44-04:00, 2009:08:11 14:28:44-04:00, 2009:08:11 14:32:20-04:00, 2009:08:11 15:17:13-04:00, 2009:08:11 15:18:26-04:00, 2009:08:11 16:06:10-04:00, 2009:08:11 16:06:10-04:00, 2009:08:11 16:11:37-04:00, 2009:08:11 16:27:45-04:00, 2009:08:11 16:33:06-04:00, 2009:08:31 14:36:18-04:00, 2009:08:31 14:39:10-04:00, 2009:09:28 07:58:34-04:00, 2010:01:19 11:40:26-05:00, 2010:01:19 12:20:55-05:00, 2010:01:19 12:25:45-05:00, 2010:01:19 13:54:47-05:00, 2010:01:19 13:56:10-05:00, 2010:01:19 14:00:52-05:00, 2010:01:19 14:21:49-05:00, 2010:01:19 14:24:44-05:00, 2010:01:19 14:24:59-05:00, 2010:01:19 16:14:02-05:00, 2010:01:19 16:14:02-05:00, 2010:01:19 16:14:42-05:00, 2010:01:19 16:24:25-05:00, 2010:01:19 16:31:13-05:00, 2010:01:19 16:38:17-05:00, 2010:01:19 16:43:33-05:00 History Software Agent : Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0, Adobe InDesign 6.0 History Changed : /, /metadata, /, /, /, /metadata, /;/metadata, /, /, /, /, /, /, /, /, /, /, /, /, /, /, /, /metadata, /;/metadata, /, /, /, /, / Manifest Link Form : ReferenceStream, ReferenceStream Manifest Placed X Resolution : 72.00, 72.00 Manifest Placed Y Resolution : 72.00, 72.00 Manifest Placed Resolution Unit : Inches, Inches Manifest Reference Instance ID : uuid:F339A58529DEDB118689DD1DECACB570, uuid:D36E0BBF4BA4DC118662D32DBD49DAAA Manifest Reference Document ID : uuid:EF39A58529DEDB118689DD1DECACB570, uuid:966BB2EA1EA4DC118662D32DBD49DAAA Doc Change Count : 1877 Format : application/pdf Producer : Adobe PDF Library 9.0 Trapped : False Page Count : 2 Creator : Adobe InDesign CS4 (6.0.4)EXIF Metadata provided by EXIF.tools