OSO FAULT FINDING GUIDE
-12-
FAULT
NOTE: Disconnect electrical supply before removing any electrical equipment covers
POSSIBLE CAUSE
REMEDY
No water flow from hot taps
1. Mains supply off.
2. Strainer blocked.
3. Cold water inlet Pressure
Reducing Valve incorrectly fitted.
1. Check and open stopcock
2. Turn off water supply. Remove
strainer and clean. (See
Pressure Reducing Valve page
6 Installation Manual)
3. Check and refit as required,
(see item 3 page 5 of installation
manual).
Water from hot taps is cold.
1. Low solar gain.
2. Immersion heaters not switched
on.
3. Immersion heater thermal cut-
out has operated.
4. Programmer set to central
heating or not switched on.
5. Boiler not working.
6. Cylinder thermal cut-out has
operated. (Indirect units only).
7. Motorised valve not operating
correctly.
1. Activate alternative power source.
2. Check and switch on.
3. Check and reset button. (See
thermostat diagram page 9 and
safety cut-out on page 4 of
installation manual).
4. Check and set to hot water.
5. Check boiler operation. If fault
suspected consult installer or
boiler manufacturer.
6. As at No. 2.
7. Check wiring and / or plumbing
connections to motorised valve.
(See pages 8 or 10 of the
installation manual).
Intermittent water discharge.
1. Reduced internal expansion.
2. Thermal control failure.
(Note Water will be hot).
1. Recharge “air gap” (See cold
water discharge on page 4 of
installation manual).
2. Switch off power to immersion
heater(s) and boiler supply to
the unit. When discharge has
stopped, check thermal controls,
replace it faulty. Contact a
competent person.
Continuous water discharge.
1. Cold water inlet Pressure
Reducing Valve not working.
2. Temperature and pressure relief
valve faulty.
3. Expansion relief valve not
working correctly.
1. Check pressure from valve if
greater than 2.1 bar replace.
(See page 6 of installation
manual).
2. As No. 2 of above.
3. Check and replace if faulty.
(See page 6 of installation
manual).