Vaillant ecoTEC plus VU 446/5-5 (H-GB) Installation And Maintenance Instructions Manual page 34

10 Troubleshooting
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18. Reinstall the components in the reverse order. You
must use new seals at position (4) and (5). Follow the
tightening sequence for the three screws that connect
the fan to the mixture pipe by following the numbering
(1), (2) and (3).
19. Screw the gas pipe onto the gas valve assembly. Use
new seals for this.
20. Hold on to the gas valve assembly when tightening the
union nuts.
21. Once the new components have been installed, carry
out the following steps.
Condition: Gas valve assembly
–
Carry out a leak-tightness check, check the CO2
content and adjust this, if required.
Condition: Venturi
–
Check the CO₂ content and adjust this, if re-
quired.
Condition: Fan
–
Check the CO₂ content and adjust this, if re-
quired.
10.9.5 Replacing the heat exchanger
1. Remove the adapter for the flue system.
2. Remove the compact thermal module. (→ Page 37)
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3. Remove the clips (1).
4. Loosen the flow (2) and return pipe (3).
5. Remove the condensate discharge hose (4) from the
heat exchanger.
6. Remove the rainwater drain hose (6) from the heat ex-
changer.
7. Remove the plug (5).
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8. Remove the screws (1) and (3).
9. Remove the retainer for the heat exchanger (2) and (4).
10. Pull the heat exchanger downwards and to the right,
and remove it from the product.
11. Install the new heat exchanger in reverse order.
Caution.
Risk of poisoning due to escaping flue
gas.
Mineral-oil-based greases can damage the
seals.
Installation and maintenance instructions ecoTEC plus 0020261389_02
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