Checking The Flow Limiter (Only For Gas Condensing Combi Boiler); Checking The Expansion Vessel And System Pressure - Viessmann B0KA Installation And Service Instructions Manual

Checking the flow limiter (only for gas condensing combi boiler)

Fig. 36
Flow limiter
Device type
B0KA-19
BPKA-19
B0KA-25
B0KA-25-M
BPKA-25

Checking the expansion vessel and system pressure

Note
The expansion vessel can lose some of its charge
pressure over time. When the boiler heats up, the
pressure rises to 2 or 3 bar (0.2 or 0.3 MPa). The
safety valve may also respond and discharge the
excess pressure.
Therefore check the expansion vessel pre-charge
pressure annually.
Check whether the installed expansion vessel is ade-
quate for the system water volume.
Carry out this test on a cold system.
4.
3.
A
2.
Serial no.
(type plate)
7721280
7721282
7721284
7721286
7721975
7721281
7721283
7721285
7721287
7721980
7721982
7721984
7721976
Commissioning, inspection, maintenance
1. Drain the boiler on the DHW side.
2. Remove the spring clip.
3. Remove the DHW flow sensor.
4. Check flow limiter . Replace in case of exces-
A
sive scaling or damage. Reinsert.
5. Mount DHW flow sensor with new gaskets.
Danger
Risk of electric shock from escaping heating
water or DHW
Check all water side connections for tight-
ness.
Flow rate
l/min
12
12
12
12
12
14
14
14
14
14
14
14
14
1. Drain the system until "0" is shown on the display.
Note
For pressure indicator on the home screen,
repeatedly until the pressure gauge symbol is
displayed.
2. If the pre-charge pressure of the expansion vessel
is lower than the static system pressure: Top up
with nitrogen at the valve of the diaphragm expan-
sion vessel until the pre-charge pressure is 0.1 to
0.2 bar (10 to 20 kPa) higher than the static system
pressure.
Colour
Red
Red
Red
Red
Red
Pink
Pink
Pink
Pink
Pink
Pink
Pink
Pink
47