Cleaning The Heat Exchanger; Descaling The Heat Exchanger - Vaillant ecoTEC plus VU Series Installation And Maintenance Instructions Manual

1. Use the main switch to switch off the product.
2. Close the gas isolator cock.
3. Remove the front casing. (→ Page 11)
4. Tilt the electronics box forward.
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5. Unscrew the retaining screw (3).
6. Tilt the air intake pipe (2) forwards.
7. Remove the air intake pipe from the intake manifold.
8. Remove the ignition line and ground connection plugs
from the ignition electrode (5).
9. Disconnect the gas line (9) from the underside of the
gas valve.
10. Pull out the cable (7) from the connection plug in the
supply line to the fan motor, the PWM signal cable on
the underside of the fan (8) and the cable to the gas
valve (10).
11. Unscrew the six nuts (4).
12. Remove the entire compact thermal module (6) from
the heat exchanger (1).
13. Check the burner and the heat exchanger for damage
and dirt.
14. If necessary, clean or replace the components accord-
ing to the following sections.
15. Replace the burner insulation on the back wall of the
heat exchanger.
16. Check the burner insulation on the burner flange. If
you notice any signs of damage, replace the burner
insulation.
0020029173_04 ecoTEC plus Installation and maintenance instructions
Inspection and maintenance 8
8.4

Cleaning the heat exchanger

1. Protect the folded down electronics box against sprayed
water.
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2. Use vinegar (max. 5% acid) to clean the heating coils
(2) on the heat exchanger (1).
3. After a reaction time of 20 minutes, use a sharp jet of
water or a plastic brush to rinse the loosened dirt. Do
not point the water jet directly at the burner insulation
on the back of the heat exchanger.
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The water flows out of the heat exchanger through
the condensate trap.
8.5

Descaling the heat exchanger

1. Drain the product. (→ Page 27)
2. Remove the automatic air vent from the air separator.
3. Fill the product with descaler (ET 990098) via the open
connection on the automatic air vent.
4. Fill the product with clean water up to the nominal pres-
sure.
5. Set the pump to "Continuous".
6. Use the chimney sweep button to heat up the product.
7. Leave the descaler to work in maximum output opera-
tion for approx. 30 minutes.
8. Then thoroughly rinse out the product with clean water.
9. Set the pump back to its starting condition.
10. Open the service valves and, if required, fill the heating
installation.
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