When reassembling the cover make sure that the regulation knob is coupled with
the thermostat.
Check controls (where fitted) as per the following:
- Line strainer - with the water supply turned off remove screen from strainer and
clean of any detritus;
- Expansion vessel - with the water supply turned off and taps open, check expansion
vessel pressure and top up as necessary;
- Temperature & pressure relief valve - with the water supply turned on, check
manually by lifting the test lever/turning the test knob (ensure valve closes after
testing);
- Expansion relief valve - check manually by turning the test knob (ensure valve
closes after testing);
- Discharge pipes (D1) - from both temperature & pressure relief and expansion relief
valve for obstructions;
- Tundish & discharge pipe (D2)- open either valve gradually to produce a full bore
discharge into tundish and D2 without any back pressure;
- Pressure reducing valve - check that the correct outlet pressure is being maintained
by recording the pressure at an in-line terminal fitting i.e. tap.
Fault finding
1) Pressure and temperature valve dripping/running all the time.
Cause: Thermal cut-out and thermostat have failed (this is only the case if the
water being discharged is near to boiling).
Mains pressure is too high. A pressure reducing valve must be fitted (see fig. 3).
2) Pressure relief valve dripping/running all the time.
Cause: Mains pressure is above 3.5 bar. A pressure reducing valve must be fitted
(see fig. 2).
3) Dripping while unit heating.
Cause: Not enough pipe work for expansion; or stop-cock, non-return valve or
pressure reducing valve has been fitted on the cold mains supply (see fig. 2). If an
expansion vessel has been fitted, the charge may have failed.
4) No hot water.
Cause: Thermal cut-out has operated.
The heating element has burnt-out.
The thermostat is faulty.
5) Milky water.
Cause: This is a result of heavily limed and oxygenated water being heated. This
is harmless and the cause is the water or a loose jumper washer in the outlet
tap and not the heater itself.
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