57
Response FF80
- Installation
87 Low system pressure light is on.
Check the pressure on the gauge on the boiler
control panel.
Is it reading below 0.5 bar ?
Is this a new
installation ?
NO
NO
Fill and repressurise the system but leave
the boiler OFF.
Check boiler heat exchanger, all CH
pipework and radiators for leaks, including
loft or underfloor pipes where used.
Was a leak found ?
YES
Increase the system pressure, if necessary,
to 1 bar.
Does the boiler now operate ?
Has it
recently
been
extended ?
Fill and
pressurise the
system
Add extra
expansion
volume
YES
YES
NO
Are there any obvious leaks ?
Fill and
repressurise the
system
Has it been partly
drained to move a
radiator ?
NO
NO
Check that the wiring to the pressure switch
terminals 1, 2 and 3 corresponds with that
shown in the wiring diagrams herein.
Was an error found ?
YES
YES
Is volume of the system
consistent with volume of
the expansion vessel(s)
fitted ?
NO
NO
NO
NO
YES
NO
FAULT FINDING
Check discharge pipe from the
safety valve (this may well be
outside the building).
Has it been discharging water ?
NO
NO
YES
Is the safety valve free
from foreign matter,
correctly set and in the
closed position ?
NO
YES
Replace safety valve and
refill / repressurise
Fire the boiler up on CH.
Observe pressure gauge as
system reaches
temperature.
Does pressure reach (or
exceed) 2.5 bars ?
YES
Check for
obstruction
in pipe
feeding
expansion
vessel
Clear and readjust the valve.
Repressurise the system
Recheck for leaks on
pipes and radiators
Unscrew the Schrader valve from expansion vessel
and fit new valve (e.g. from car tyre sales outlet).
Repressurise expansion vessel to 1 bar (15 lb/in
2
).
Does vessel pressure hold up ?
Fill and
repressurise
system
YES
Replace
expansion
vessel
F
AUL
T FINDING
Use a drain cock (not the safety valve) to release all
pressure on the boiler pressure gauge. Remove cap from
the air valve on the expansion vessel.
Measure air pressure with a car tyre pressure gauge.
Is it at least 0.8 bar (12 lb/in
2
) ?
NO
Is there continuity
between terminals
1and 3 on pressure
switch?
NO
Change
pressure
switch
