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| Troubleshooting | |
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Display | Cause | Solution |
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C1 | Fan rotation too low on startup. | 1. Disconnect power supply cord. Check wire |
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| (part# 8707204039) | connections on back side of fan and the two large |
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| wire connectors on the control unit. Removal of |
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| lower access panel on control unit is necessary to |
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| access connectors. |
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| 2. Verify that supply voltage is 120VAC and is |
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| properly grounded. |
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| 3. Verify that venting meets specifications outlined |
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| in chapter 3.6. Long vent lengths, venting with more |
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| than three elbows, blocked vent or combination |
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| venting may cause this failure. Verify backdraft |
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| flapper inside flue gas collector is not stuck shut. |
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| 4. Check gas pressure. See chapter 3.8. Low gas |
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| pressure may cause the fan to change its speed to |
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| meet desired temperature. |
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| 5. Possible defective control unit. Call Bosch Water |
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| Heating for further instructions. |
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C6 | Fan rotation too low in operation | 1. Disconnect power supply cord. Check wire |
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| (part# 8707204039) | connections on back side of fan and the two large |
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| wire connectors on the control unit. Removal of |
|
|
| lower access panel on control unit is necessary to |
|
|
| access connectors. |
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| 2. Check supply voltage is 120VAC and is properly |
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| grounded. |
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| 3. Verify that venting meets specifications outlined |
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| in chapter 3.6. Long vent lengths, venting with more |
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| than three elbows, blocked vent or combination |
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| venting may cause this failure. Verify backdraft |
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| flapper inside flue gas collector is not stuck shut. |
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| 4. Ensure intake and exhaust terminations maintain |
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| the required clearances stated in the manual ( Fig. |
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| 17 and Table 6 on page 17). Cross |
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| contamination between intake and exhaust may |
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| cause the fan to alter its rotational speed. |
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| 5. Check gas pressure. See chapter 3.8*. Low gas |
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| pressure may cause the fan to change its speed to |
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| meet desired temperature. |
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| 6. Possible defective control unit. Call Bosch Water |
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C7 | No rotational speed sensor from fan. | 1. Disconnect power supply cord. Check wire |
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| (part# 8707204039) | connections on back side of fan and the two large |
|
|
| wire connectors on the control unit. Removal of |
|
|
| lower access panel on control unit is necessary to |
|
|
| access connectors. |
|
|
| 2. Check supply voltage is 120VAC and is properly |
|
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| grounded. |
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| 3. Possible defective component in fan. Call Bosch |
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| Water Heating for further instructions. |
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CA | Water flow signal over specified maximum | 1. Disconnect power supply cord and check wire |
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| value. | connections on water valve and the two connectors |
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| (part# 8708505016) | on the control board. |
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| 2. Excessive water pressure and flow. Ensure water |
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| pressure is less than 150psi and flow rate is less |
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| than 10 gallons per minute. |
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Table 12
* By installer or service technician only.
6 720 608 263 | 37 |