Vaillant ecoTEC exclusive VC 156/5‑7 N-DE Installation And Maintenance Instructions Manual page 26

10 Troubleshooting
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2. Remove the air intake pipe.
3. Remove the two plugs from the gas valve.
4. Unscrew the cap nut from the gas valve.
5. Unscrew both screws to secure the gas valve to the fan.
6. Reinstall the new gas valve in the reverse order. Use
new seals for this.
7. Read the offset value (1) that is imprinted on the new
gas valve.
8. After installing the new gas valve, carry out a leak-tight-
ness test (→ Page 21).
9. Close the front casing.
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10. Switch on the product.
11. Navigate to Menu → Installer level → Diagnostics
menu → D.052 Min. gas valve steps offset and con-
firm by pressing
12. Enter the offset value that you read off and confirm by
pressing
13. Carry out initial start-up. (→ Page 20)
10.7.3 Replacing the fan
1. Remove the air intake pipe.
2. Remove the gas valve (→ Page 25).
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3. Remove the plug (1) from the fan.
4. Unscrew the three screws between the mixture pipe
and the fan flange.
5. Replace the defective fan.
6. Reinstall the new fan in the reverse order. You must
use new seals for this. Ensure that the order in which
the three screws are screwed in between the fan and
the mixture pipe corresponds to the numbering (2), (3)
and (4).
10.7.4 Replacing the heat exchanger
1. Drain the product. (→ Page 31)
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2. Remove the compact thermal module. (→ Page 29)
3. Remove the left side section.
4. Detach the condensate discharge hose from the heat
exchanger.
Installation and maintenance instructions ecoTEC exclusive 0020186710_06
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