Central heating turning on by itself

slipthru · 2 February 2010 at 8:56AM

I have Ideal icos boiler with a hot water cylinder and timer switch in a bedroom upstairs, it sometimes turns on in the middle of the night when the timer is switched of and the temp control is turned down. Now it has started not turning the heating off when the timer turns of at 10pm, i have to turn the temp stat down to get the boiler to switch off.

What could be the problem?

david29dpo · 2 February 2010 at 9:31AM

Sounds like the timers duff.

DrScotsman · 2 February 2010 at 9:50AM

I don't know about the second problem, but I can tell you my Ideal's manual says that if the temperature gets too cold then it'll turn itself on so the pipes don't freeze. Might explain it turning on in the middle of the night for you.

millie · 2 February 2010 at 9:52AM

Is it heating up the radiators because we used to have a Valliant combination boiler and there was a function that allowed the storage of a small tank of hot water, I asume because we had to run the water for quite a time to get it hot. With the small storage tank it was instant like an immersion heater. After we had it serviced we noticed that it kept lighting up for a few minutes ocassionally during the night (as the boiler was in the airing cuboard. We called the engineer back and there is a switch to turn this operation on and off and he had left it switched on. So perhaps that is the problem if you have this on your boiler. It was keeping this small tank of water up to the temperature the thermosat setting.

slipthru · 2 February 2010 at 10:17AM

Thanks for all the replies, it's actually a new system to us as we only moved in a few months ago.

I wasn't aware that ideal boilers had frost protection built in (will have to scan the manual again), I had read about frost stats but can't find one in the house, the boiler is situated in the kitchen though which has no radiator and gets quite cold compared to the rest of the house so I guess that could be a reason.

Apart from the on/off switch there are no other switches on the boiler, so not sure that it has another small tank of hot water.

I forgot to mention that there is a ticking in the airing cupboard in the bedroom when the timers switch on in the morning and evening, this is how I knew it was switching on in the middle of the night.

gas4you · 2 February 2010 at 11:40AM

Never known an Ideal boiler to have frost protection as yet.

This sounds more like a stuck zone valve. You will either have 2 x 2 port valves or 1 x 3 port valve.

Could be just the microswitch in the acuator head has broken and stuck on.

It is these valves that tell the boiler to come on, not the programmer or thermostats.

slipthru · 2 February 2010 at 12:30PM

Thanks for your reply gas4you have had another look in the cupboard and can see a drayton mid port valve actuator ma1, is it something simple to take a look at to see if it's stuck?

gas4you · 2 February 2010 at 12:36PM

It could be the acuator head that is at fault, and as you say your system is new I would tend to go for this rather than the valve body stuck.

The only way you can definately tell is to test the wires off the valve with a multimeter.

However, due to the voltage being 240VAC, I would not advise anyone testing this themselves unless they are safe and competent to work with live electric.

240 can kill

slipthru · 2 February 2010 at 12:45PM

Thanks for your help, it's not new new, it's about three years old according to the previous owners, it's new to us as we just bought the house a few months ago, the flat we lived in before had a combi boiler so I didn't know anything about this kind of heating system.

By the sounds of it I should call a heating engineer out to take a look, I've never dealt with electrics before.

gas4you · 2 February 2010 at 12:47PM

Thats sensible.

Whoever you call, tell them the make and model. They should be able to bring one with them for a first time fix.

If they dont need it they can always take it back.

slipthru · 2 February 2010 at 5:44PM

I've been quoted £125 for the parts and labour, does this sound ok?

Central heating turning on by itself

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