Fabdec EXCELSIOR Installation Manual - page 24
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6.
Fault Finding
WARNING: Disconnect electrical supply before removing any electrical equipment cover.
Fault
Possible cause
Remedy
The cylinder cools down overnight
One pipe circulation in the case of
short pipe networks with low pressure
loss
Install a non-return valve as close as
possible to the cylinder
Primary heating is not working. Boiler
runs for a short period, goes off, then
comes on again. This is repeated until
the cylinder reaches its target
temperature
Air trapped in heat exchanger
Heat exchanger surface too small
Vent air from heat exchanger circuit
Check data for boiler and cylinder. The
problem may be solved by increasing
the flow from boiler
Only cold or lukewarm water comes
out of taps
Programmer set to heating only or not
switched on for hot water
Central heating boiler malfunction
High limit thermostat has tripped
Pump malfunction
If only cold water comes out of taps,
hot and cold pipes may have been
connected up incorrectly
Set programmer to call for hot water
on demand
Check boiler operation. If faulty consult
manufacturers instruction manual
Check and re-set. The cause will need
to be identified
Check wiring and/or plumbing
connections to pump
Check connections and have them
changed if necessary
Intermittent water discharge through
tundish on warm up
Expansion vessel has lost its charge
pressure (vessels with external
expansion only)
Internal air gap needs replenishing
Follow steps listed in Service &
maintenance section
Follow steps listed in Servicing &
maintenance section
Continuous water discharge
Pressure reducing valve (PRV) not
functioning properly
Expansion relief valve not seating
correctly
Temperature & pressure relief valve
not seating correctly
Check pressure from PRV. Replace
cartridge if necessary
Manually lift the valve once or twice to
clear debris from the seat. If this does
not cure problem, replace valve
Manually lift the valve once or twice to
clear debris from the seat. If this does
not cure problem, replace valve