Warnflow Oil Central Heating Condenser Boiler turning itself on

[barrymurphy]

Hi,

The boiler is coming on when the timer clock is set to off. Because the timer clock is off no motorised valves open and so no heat gets around the house but the radiator nearest the boiler gets hot, (obviously not controlled by the valves).

Why would this happen?

The control box was recently replaced, about two months ago but all has been fine and this has only started happening the past week.

Thanks

Barry
[automerge]1603883684[/automerge]

Hi,

The boiler is coming on when the timer clock is set to off. Because the timer clock is off no motorised valves open and so no heat gets around the house but the radiator nearest the boiler gets hot, (obviously not controlled by the valves).

Why would this happen?

The control box was recently replaced, about two months ago but all has been fine and this has only started happening the past week.

Thanks

Barry

The two motorised valves had their motors replaced and open and close as they should.

Could this be an aux switch stuck closed?

 

[SJB060685]

If you're competent with a multimeter you can check to see if the motorised valve end switch is stuck closed. Even with the programmer off this will still switch a permanent live to boiler feed, subsequently bringing it on.
Another option is a frost stat somewhere?
If you're not comfortable with a multimeter then please get an engineer out, this is badic stuff so you shouldn't have a problem finding someone.

 

[barrymurphy]

Yes, comfortable with a multi meter. No frost stat, al least don't think so. Never had this before and we have had plenty of frost. The valves are 12 years old and I have replaced the motors so its now the electrics have gone most likely.

I assume the only cure is a new valve? aux switch not repairable?

 

[SJB060685]

I would replace the whole valve/valves, you might be able to make and electrical repair but for the price of a valve its probably not worth it.
To confirm my suspicion and only if you're confident with a multimeter you can check in the wiring centre between a neutral and the boiler switch live. If there's 230 volts then I would say its the end switch, although I would rule out a rogue supply from programmer to valve motor as well.

 

[Brambles]

Start at the terminals calling the boiler for heat. Then work backwards logically through the wiring to determine where the erroneous call for heat is coming from.

Do not assume that the new external control system has always worked properly or indeed that it has been wired / configured properly. It may be ok for DHW but not CH

With a bit of patience you will find the gremlin