Can't turn central heating off! Can anyone advise?

Boxdonkey

Hi there, I'm new here so hope this is posted in the right section.

A few days ago my central heating came on full blast throughout the house which I found strange as I've had it turned off for the summer.

I checked the thermostat and it's turned down as far as it will go, and the timer control panel is definitely set to OFF for the central heating, with the hot water set to come on a couple of times a day.

But the heating's continued to come on for the last few days - it seems to come on every time the hot water comes on. I should mention that every radiator in the house is RED HOT.

As a temporary measure I've turned all the radiators off. Is this a safe move or could it cause something to burst or blow up? (Apologies if that's a daft question but I know absolutely nothing about heating systems!)

Am I right in guessing the fault is neither with the thermostat nor the timer control panel, as both are set to the OFF position, so therefore if one was faulty, the other one would just cancel it out, and the heating would remain off?

Here are some details in case they help to identify the problem:
• Modern new build 3 bedroom house (5 years old)
• Boiler is a Glowworm Micron in the kitchen
• Hot water cylinder is upstairs in airing cupboard
• Control panel is Honeywell C27 in the kitchen
• Thermostat is in hallway next to front door

Could anyone advise on the likely cause, and if possible give me a very rough idea of what it's going to cost to get fixed?

Many thanks.

Canucklehead

Hi

I would look to the 2 or 3 port motorised valve (probably in the cylinder cupboard.)
Most can be separated, ie head from body.


Corgi Guy.

konj

We had a very similar problem a while ago. It was the "diverter valve". This motorized valve diverts the hot water from the boiler to either your radiators or your hot water tank. If it gets stuck to the radiator setting then the thermostat on the h/w tank will demand heat from the boiler, but all this heat will go to your radiators - and not stop. Cost of replacement would probably depend on how accessible the valve is.

wannabe_a_mum

This happened to us about 3 weeks ago - Central Heating came on during the night - it was roasting!!!
We couldn't figure it out as it was OFF etc.

Hubby had a look later that day and don't know how he came to know thisn, but he changed the batteries in the timer console and it worked.
Apparently it's a common cause?? (According to an ex-BG engineer)

Akom

Sometimes the diverter valve does get stuck as suggested earlier. Depending on the type you have you maybe able to manualy change this very easily.

In the airing cupboard you may find a silver box with 3 pipes going into it and a cable coming out of it. On the side of this there maybe a lever. This lever allows you to manually change the diverter. It will be stiff to move and will make a wirring noise as you move it. Move this to the opposite end of were you started. Should be a little locking groove for it or will spring back to its starting position.

This is not a repair just a way to turn your heating off and give you hot water only. You will still have to have it looked at.

Hope this helps.