Checking The Diaphragm Expansion Vessel And System Pressure - Viessmann VITODENS 242-F Installation And Service Instructions Manual

Further details regarding the individual steps
3. Fit flange cover B and tighten eight
screws D with a maximum torque of
25 Nm.
4. Push earth cable C onto the tab.

Checking the diaphragm expansion vessel and system pressure

A
Note
(GB only) The diaphragm expansion
vessel can lose some charge pressure
over a time in use. When the boiler heats
up, the pressure gauge will indicate a
higher pressure of 2 or 3 bar (0.2 or
0.3 MPa). The safety valve too can
respond and discharge excess pres-
sure.
Commissioning, inspection, maintenance
(cont.)
5. Fit cover E.
6. Fill the primary store with potable
water.
Check whether the installed diaphragm
expansion vessel is adequate for the
system water volume. (GB only)
Note
Carry out this test on a cold system.
1. Drain the system until the pressure
gauge shows "0".
2. If the diaphragm expansion vessel
pre-charge pressure is lower than the
static system pressure: Top up with
nitrogen at connection A until the
pre-charge pressure is 0.1 to 0.2 bar
(10 to 20 kPa) higher than the static
system pressure.
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 dia-
phragm expansion vessel.
Permiss. operating pressure: 3 bar
(300 kPa).
69