Checking The Expansion Vessel And System Pressure; Checking The Water Quality; Checking The Mixer For Ease Of Operation And Leaks; Checking All Connections On The Heating Water And Dhw Sides For Leaks - Viessmann VITOCROSSAL Service Instructions Manual

Checking the expansion vessel and system pressure

Note
Check when system is cold.
1. Drain the system or close the cap valve on the
expansion vessel. Reduce pressure until the pres-
sure gauge shows "0".
2. If the pre-charge pressure of the expansion vessel
is lower than the static system pressure: Top up
with nitrogen until the pre-charge pressure is 0.1 to
0.2 bar (10 to 20 kPa) higher.

Checking the water quality

Enter the amount of top-up water and the total hard-
ness of the feedwater and boiler water in the table in
the appendix (page 104).
For water quality requirements, see page 102.

Checking the mixer for ease of operation and leaks

1. Remove the motorised lever from the mixer han-
dle.
2. Check the mixer for ease of operation.

Checking all connections on the heating water and DHW sides for leaks

Checking the safety valve function

Installing the burner

Refit the burner in reverse order to the removal.
■ Burners up to 80 kW see page 18.
■ Burners 120 to 160 kW see page 19.
■ Burners from 200 kW see page 20.

Checking the firm seating of electrical connections

Checking all gas equipment for tightness at operating pressure

Danger
Escaping gas leads to a risk of explosion.
Check all gas equipment for tightness.
Commissioning, inspection, maintenance
3. Top up with water until the charge pressure of the
cooled system is 0.1 to 0.2 bar (10 to 20 kPa)
higher than the pre-charge pressure of the expan-
sion vessel.
Permiss. operating pressure: 6 bar (0.6 MPa)
Minimum operating pressure: 1 bar (0.1 MPa)
Note
The minimum operating pressure is essential for
safe operation. It can be ensured by a minimum
pressure switch (on site). For multi boiler systems,
use 1 minimum pressure switch (on site) per sys-
tem.
The total hardness of the feed and top-up water must
not exceed the standard values specified by VDI 2035
(see page 102).
The pH value should be between 8.2 and 10.0.
3. Check the mixer for leaks. In the event of a leak,
replace the O-rings.
4. Click the motorised lever into place.
Insert the burner. Secure screws by hand. Tighten
screws diagonally, torque 10 Nm.
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