Boiler not switching off Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Trev535]

Hi, Just got back after a fortnight away, and at 01.30 last night, I thought I could hear the C/H pump running. Got up to investigate, and sure enough it was on. Checked the programmer and both c/h and h/w valves and they were all off. First instinct was to take the front of the programmer off, but pump carried on running. Went downstairs and discovered the boiler burner was lit.(God knows how long this has been on?) I then switched off the main c/h switch and the boiler shut down and the pump stopped.

This morning I switched the main switch on again, and low and behold, the boiler lit up and pump started running again, bearing in mind the programmer is still not connected.

Any ideas what the problem is? I'm thinking boiler thermocouple but will take advice. Thank you.

[DEEARR2]

Hi Trev, thermocouple is not relative to the pump and the boiler burner on /off control, it monitors the pilot and is a fail safe device. You refer to ch and hot water valves which I take are motorised control valves attached to a conventional boiler. There is obviously an electrical fault in the control wiring that may be associated with the micro switches located in the motorised valves which indirectly control the pump and boiler on demand. Advise having the system checked over by a GSR engineer.

[htg engineer]

Frost stat on the system ? it may be faulty.


htg

[Trev535]

Thanks for the speedy replies guys. Problem solved. Found the H/W valve was seized in the open position. There had been a small leak from the valve gland and that had caused corrosion to the return spring which weakened it and it had broke. Quick trip to B&Q (only place open on a Saturday afternoon) to get a new valve, fitted it, and all is well again.

Thank again.

Cheers Trev.

[Trev535]

Well the system worked OK for a day, then this morning the pilot light was out. Tried lighting it three times, but every time I let go of the button, pilot went out. Figured the thermocouple was goosed so I managed to get one from Plumb Centre. Fitted it this evening. The old one was broken where the tube enters the probe. But no joy. Pilot will not stay alight when the button is released. Even tried holding the button in for a good 5 minutes (should be 15 seconds) just to get plenty of heat there. Any suggestions before I call a professional in?

The boiler is a Baxi Solo 2, RS50. 1995 vintage (maybe time for a new one) It's been serviced every 2nd year with no issues and this is the first time it's gone wrong.