Vaillant ecoTEC sustain 24 Installation And Maintenance Instructions Manual page 41

12. Refit the entire fan/gas valve assembly unit in reverse
order. You must use a new seal (5) for this.
13. Ensure that the order in which the three screws are
screwed in between the fan and the mixture pipe cor-
responds to the numbering (3), (2) and (4).
14. Tighten the union nut (2) on the gas valve assembly
and the union nut (8) between the gas pipes. In the
process, secure the gas pipe against twisting. Use new
seals for this.
15. After you have completed this work, carry out a leak-
tightness test (function check). (→ Page 32)
16. If you have installed a new gas valve assembly, adjust
the gas setting. (→ Page 36)
13.7.3 Replacing the heat exchanger
1. Drain the product. (→ Page 39)
2. Detach the condensate discharge hose from the heat
exchanger.
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3
2
3. Remove the clamps (2) and (3) from the area of the
flow and return connection.
4. Disconnect the flow connection.
5. Disconnect the return connection.
6. Remove both screws (1) from both brackets.
7. Remove the lower three screws (2) on the rear section
of the retainer.
8. Move the bracket round to the opposite side and attach
the upper screw (1) to the side.
9. Pull the heat exchanger downwards and to the right,
and remove it from the product.
10. Install the new heat exchanger in reverse order.
11. Replace the seals.
0020253094_05 ecoTEC sustain Installation and maintenance instructions
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2
Note
Instead of grease, use only water or com-
mercially available soft soap to aid installa-
tion.
12. Insert the flow and return connections into the heat
exchanger as far as they will go.
13. Ensure that the clamps are correctly fitted to the flow
and return connections.
14. Fill and purge the unit and, if required, the heating in-
stallation. (→ Page 29)
13.7.4 Replacing the expansion vessel
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1. Prepare the repair work. (→ Page 40)
2. Undo the screwed connection (4).
3. Remove both screws (1) on the support plate (2).
4. Remove the support plate (2).
5. Pull out the expansion vessel (3) towards the front.
6. Insert the new expansion vessel into the product.
7. Screw the new expansion vessel to the water connec-
tion. Use a new seal for this.
8. Attach the support plate using both screws (1).
9. Fill and purge the product and, if required, the heating
installation (→ Page 29).
10. If necessary, adjust the pressure to the static height of
the heating installation.
11. Complete the repair work. (→ Page 43)
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