Radiators warming up by themselves

[Gti]

Central heating hasn't been used once since january, no it's not on the timer. Damn things heat up when using hot water for a shower or doing the dishes.
Is this normal? Would bleeding the radiators solve this?
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[M]

[cagiva gezzer]

Combi boiler or old style?

Could be the 3-port valve stuck and sending heat to the radiators when you're only wanting HWS.
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"because one stroke isnt enough and four strokes waste two"

[yen_powell]

[Bendy]

Yup, stuck valve is what happened to ours.

[cal91]

Same it sounds like a suck valve.
Ours does it often lol. We have lived in this house 4 years and the servo has been replaced twice and its currently broke.

We have give up, atm the servo is off the valve and I'm manually turning it between HWS and Heating.
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We are the Patriots! Love your country.

[Gti]

combi.

Don't trust myself to fiddle with the boiler so i'll go with flicking the heating on and off. Any suggestions on how many times and for how long to free up the valve?
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[M]

[yen_powell]

[cal91]

Yeah I agree with him ^^^
Mines near the hot water tank too. Its not actually on the boiler.
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We are the Patriots! Love your country.

[Gti]

Im in a flat, don't think there is a tank? Where would it be
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[M]

[Phoenix]

Another vote for stuck valve, it's usually big red thing in the pipework, there's sometimes a manual switch on the bottom of it to change the position, but as it's more likely that it's just siezed this won't really help. Looking at about £70-80 for a new one. As you have a combi boiler then you have no need for a hot water tank as hot water is supplied on demand, presumably the valve will be in a cupboard somewhere where the tank used to be (assuming the flat is not a new building).

[Mrs Kickstart]

[Gti]

It's the bedroom radiator that's doing it, and only the top half seems to warm up.

Apparently it played up today as well my gf used the hot water when she was doing the washing up and the boiler started making a loud racket, steam came out the top of it and she had to switch it off.
i checked the pressure gauge it looks in normal range (1-1.5 mines 1) now but at the time it was redlining im guessing the pressure safety valve kicked in hence the noise.
should i put that down to a one off?
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[M]

[Al]

Like Mrs Kickstart said, often combi boilers have a pump overrun feature which will dumb excess heat from heating the hot water into the heating circuit. Although the rad should only get warm for a short while after the hot water has been used.

The pressure shooting up and steam? (do you mean the steam came from the discharge pipe, rather then the boiler itself?)
Did you have to top up the pressure afterwards?

Sounds like the bladder in the expansion vessel (normally red and in the boiler casing) could be split or need re-pressurising.

The vessel has a rubber bladder which is filled with air at about 0.75-1.0bar and as the water heats up it takes the expansion. without it the pressure will just rise as it has nowhere to go until the pressure relif valve goes off.
You can check the expansion vessel is set to the right pressure by dropping the pressure of the system to zero and connecting a foot pump to the valve on the top of the vessel.

But It may just be easier to get somebody out to look at it, as I'm only guessing and thats all anybody else can really do without looking at it.
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