Vaillant ecoTEC plus VUI Series Installation And Maintenance Instructions Manual page 49

12.8.4 Checking and, if required, supplementing
the pre-charge pressure for the internal
expansion vessel
1. Drain the product. (→ Section 12.9)
1
2. Check the pre-charge pressure of the expansion vessel
at the expansion vessel valve (1).
–
Working materials: U tube manometer
–
Working materials: Digital pressure gauge
Result 1:
≥ 0.075 MPa (≥ 0.750 bar)
The pre-charge pressure is in the permissible range.
Result 2:
< 0.075 MPa (< 0.750 bar)
▶
Top up the expansion vessel in accordance with
the static height of the heating installation, ideally
with nitrogen, otherwise with air. Ensure that the
drain valve is open when topping up.
3. If water escapes from the valve of the expansion
vessel, you must replace the expansion vessel.
(→ Section 13.7.9)
4. Fill the heating installation. (→ Section 9.9)
5. Purge the heating installation. (→ Section 9.10)
12.8.5 Checking the pre-charge pressure of the
shift-load cylinder expansion vessel
Note
One check every three years is sufficient.
1. Close the isolation valves on the domestic hot water
system.
2. Close the cold-water isolation valve.
3. Open a hot water tap to depressurise the water circuit.
Close the hot water tap.
1
4. Unscrew the screw (1) from the cover (2) of the shift-
load cylinder.
0020308121_04 Installation and maintenance instructions
5. Remove the cover.
◁
The expansion vessel is freely accessible.
6. Unscrew the sealing cap (3) from the expansion ves-
sel.
7. Check whether the pre-charge pressure of the expan-
sion vessel is approx. 0.4 MPa (4 bar). If the pressure
is lower than this, increase it using an air pump until it
is 0.4 MPa (4 bar).
8. Screw the sealing cap (3) back onto the expansion
vessel.
9. Position the cover.
10. Repressurise the heat generator and the domestic hot
water system.
12.8.6 Cleaning the condensate siphon
1. Remove the condensate adapter (1).
2
3
2. Loosen the lower section of the siphon (3) by turning
the upper section of the siphon (1) by a quarter turn
and pull it downwards and out.
3. Remove the float (2).
4. Flush out the lower section of the siphon with water.
A
1
B
4
1
2
3
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