Viessmann Vitocal 300-G Installation And Service Instructions Manual page 110

Commissioning, inspection, maintenance
Further details regarding the individual steps
Checking the diaphragm expansion vessel and the heating
circuit pressure
Carry out this test on a cold system.
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
boiler 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 above the static
system pressure.
Example:
Static head
(distance between the
heat source and the
highest heating surface)
Equals static pressure
Checking the compressor casing temperature
1. Start the heat pump and let it run
for at least 10 min (see page, point
1 and 2).
110
3. Top up with water, until the filling
pressure exceeds the pre-charge
pressure of the expansion vessel.
On a cold system, the filling pres-
sure must be approx. 0.2 bar higher
than the static pressure.
4. During commissioning, mark this
value on the pressure gauge as
minimum filling pressure.
10 m
1 bar
2. Measure the temperature of the
compressor 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
(otherwise consult the Technical
Service department at Viessmann).
(cont.)