Combi boiler burning constantly!

Thank you for the help. It sounds like the kind of roar you hear when the burner is burning; not just the pilot light (which is normally almost silent).

That seems possible. How can I determine whether it's th CH or the DHW that it's trying to heat?

It seems like it burns non-stop, almost. The only way I could stop it was to turn the boiler off. Turning the boiler's DHW oulet tap off did not stop it burning.

Thanks again.

Al D

OK that's cleared that one up.

Are the radiators getting hot?

It will either heat the rads or it will over heat within a minute or so.

First, I took the DHW flow sitch apart and can confirm that the plunger is not sticking.

Then I turned the boiler on. I had the boiler switched to DHW only (no CH). Then what I discovered surprised me: The CH return pipe immediately got hot. Then I felt the CH flow output pipe. That was not as hot as the return pipe! Does that make any sense?

Thank you,

Al D

I think they call that the "three-way valve" in my manual. Is there a way to unstick these by hand when they get stuck?

Thanks,

Al D

I've not worked on one of these to this depth. How is the three way valve operated (electric or otherwise?). Is it failing to do what it should or is it being told to do CH when it shouldn't?

It sounds like you might need some professional help.

The only wires going to the valve are the wires going to the "CH control thermistor" situated in the top of the valve, according to the schematic in the manual. Does that mean the valve is electrically controlled?

Thanks,

Al D

Shouldnt have got IMM to install it.

NT

Who the hell is IMM?

Al D

Also known a dIMM, Adam, Dr Evil and most appropriately Dr. Drivel.

He's uk.d-i-y's self appointed expert on absolutely everything.

Turns out it was the DHW flow switch. I guess an electrical fault in the switch. Replaced it. Problem cured.

Many thanks for helping me trace the problem.

AL Deveron