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11. Fault finding.
Notice: Disconnect electrical supply before removing any electrical equipment cover.
Fault
Possible cause
Remedy
No hot water
1. Mains supply off
1. Open stopcock
2. Strainer blocked
2. Turn water supply off,
remove strainer and
clean. (see 10.6)
3. Pressure reducing valve
3. Re-fit correctly
(PRV) incorrectly fitted
Water from hot taps is cold 1. Programmer set to heating
1. Set programmer to call
only or not switched on
for hot water
2. Central heating boiler
2. Check boiler operation
malfunction
if faulty consult your
boiler manufacturers
instructions
3. High limit thermostat has
3. Check and re-set
tripped
4. Motorised valve malfunction
4. Check wiring and/or
plumbing connections
to motorised valve
Intermittent water discharge 1. Expansion vessel has lost its
1. Turn off stopcock
charge pressure
open a hot water tap
check vessel charge
pressure and recharge
to 3 bar
Continuous water discharge 1. Pressure reducing valve (PRV)
1. Check pressure from
working
PRV if greater than
3 bar replace cartridge
2. Expansion relief valve not
2. Manually lift the valve
seating correctly
once or twice to clear
any debris from the seat
otherwise replace valve
3. Temperature and pressure
3. Same remedy as above
relief valve not seating correctly
