Viessmann Vitocal 350-A Installation And Service Instructions Manual page 121

Further details regarding the individual steps
Note
Only use anti-corrosion agents that have
been approved for heat pumps with
DHW heating via single-walled heat
exchangers (DHW cylinders).
1. Drain the heating water side of the
heating system and reduce the pres-
sure until the pressure gauge indi-
cates "0".
2. If the pre-charge pressure of the
expansion vessel is lower than the
static system pressure, top up with
sufficient nitrogen to raise the pre-
charge pressure of the expansion
vessel to 0.1 to 0.2 bar above the
static system pressure.
Example:
Static head
(distance between the
heat source and the high-
est heating surface)
Equals static pressure
Checking the compressor casing temperature
1. Switch ON the heat pump and oper-
ate it for at least 10 min.
Commissioning, inspection, maintenance
3. Top up with water until the filling pres-
sure exceeds the pre-charge pres-
sure of the expansion vessel.
On a cold system, the filling pressure
must be approx. 0.2 bar higher than
the static pressure.
4. During commissioning, mark this
value on the pressure gauge as min-
imum filling pressure.
10 m
1 bar
2. Measure the temperature of the com-
pressor casing exterior while it is in
operation.
Ice must not form on the outside of
the compressor, and the casing must
not become hotter than 60 °C (if nec-
essary, consult the Technical Service
department at Viessmann).
(cont.)
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