Checking The Pre-Charge Pressure And The Dhw Expansion Vessel (If Installed); Checking The Function Of The Safety Valves; Checking The Firm Seating Of Electrical Connections - Viessmann Vitodens 242-F Installation And Service Instructions Manual

Checking the diaphragm expansion vessel and...
Note
The diaphragm expansion vessel can lose charge
pressure over time in use. When the boiler heats up,
the pressure gauge indicator may rise to 2 or 3 bar
(0.2 or 0.3 MPa). The safety valve may also respond
and discharge the excess pressure.
Note
Carry out this test on a cold system.
1. Drain the system until the pressure gauge shows
"0".
2. If the expansion vessel pre-charge pressure is
lower than the static system pressure: Top up with
nitrogen at connection
sure is 0.1 to 0.2 bar (10 to 20 kPa) higher than the
static system pressure.
Checking the pre-charge pressure and the DHW expansion vessel (if instal-
led)
A
Fig. 50

Checking the function of the safety valves

Checking the firm seating of electrical connections

until the pre-charge pres-
A
Commissioning, inspection, maintenance
(cont.)
Check whether the installed diaphragm expansion ves-
sel is adequate for the system water volume.
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: 3 bar (0.3 MPa)
1. Check the static pressure of the DHW line down-
stream of the pressure reducer and adjust if
required. Set value: max. 3.0 bar (0.3 MPa).
2. Close the on-site shut-off valve in the cold water
line.
3. Turn operating lever of valve
tion.
4. Check the pre-charge pressure of the DHW expan-
sion vessel and adjust if required. Set value: Static
pressure minus 0.2 bar (0.02 MPa).
5. Turn operating lever of valve
position and open the on-site shut-off valve in the
cold water line.
to the "front" posi-
A
back to the "left"
A
57