Hot water and Central Heating off, Radiator still on!

[JamesUK]

hi there,

just found this forum, seems really useful, many thanks to the guys (and gals?) that contribute to help others.

my problem is this; recently moved and am finding that at night, when both the hot water and central heating have been turned off by the timer, one radiator stays on. the thermostat control on radiator doesn't make a difference so simply turning it down is not an option. am concerned about the energy wastage and the discomfort of a very hot room!



to try to give as much info as possible, following your criteria:

1. glowworm spacesaver complheat fanned flue sealed system boiler, gas.

2. one radiator is consistently on despite the hot water and central heating being off.

3. all radiators been recently bled, pressure in system has been increased to proper amount.

4. since we brought house but only now does it seem to be producing so much heat.

5. all the time.

6. nothing.


would really appreciate your help with this. many thanks.

 

[gasgeezer]

Possible zone valve sticking on .

 

[JamesUK]

ok, ta for that. i'm afraid my knowledge of these things is minimal! will go and research 'zone valves'. thanks for taking the time out mate.

 

[seco services]

is the boiler still firing up during the night ? as the heat must be coming from somewhere.

if the zone valve was sticking open then the other rads would still get hot not just one.

 

[JamesUK]

yes, it's odd isn't it. it must be firing up despite the timer saying both hw and ch are off. but then why only one radiator being on? and does that mean there is a problem with the timer or boiler?

 

[seco services]

where is the rad ?
if the programmer is off then the live to boiler/pump must be coming from somewhere.

what valves have you after the pump ?
one of these

or two of these

have you any pics of your airing cupboard pipework around the pump etc?

 

[JamesUK]

yes, it's odd isn't it. it must be firing up despite the timer saying both hw and ch are off. but then why only one radiator being on? and does that mean there is a problem with the timer or boiler?

 

[JamesUK]

hi seco,

thanks for taking the time out.

the radiator is in the same room as the boiler.

i seem to have two 'two port motorized valves'.

might be able to get some piccies up tomorrow.

 

[MANDATE]

sorry I can't advise you, but I can well imagine the frustration.
I'm just trying to find a logical explanation.

Could there be a frost stat, which I assume would overide the CH switch being off.
Why one radiator? could it be the pump does not function in this situation and the radiator in the same room as boiler works on gravity.
I think you had better stay up all night with your boiler and report back tomorrow.
When you do find the answer do let us know!

 

[mogget]

Gut feeling says this one radiator has been plumbed as a bypass, and that the system is wired wrongly so instead of being interlocked with the two-port valves it's cycling on the boiler stat.

As someone else mentioned, the heat must be coming from somewhere, this will be either the boiler or the hot water cylinder, barring something really bizarre like a towel rail element in the bottom of the radiator.

I'd suggest finding a way of making sure that the boiler cannot fire - isolating the electric supply or putting pilot light out etc (I don't know this model of boiler). Leave it a couple of hours without power and if the rad is still hot then the heat is definitely coming from the hot water cylinder.

Disclaimer : I am a DIYer not a professional.

 

[JamesUK]

thanks to the above two for helping.

trying to take pics now but both the wife's and my camera are uncharged!




we turned the isolator off last night and the radiator is off. so presumably that means that the boiler must be firing itself up generally, doesn't it?

how's that happening?!

 

[JamesUK]

ok, got some pics. 'scuse the mess...


first the boiler -

then the hot water cylinder -

the timer and isolator switch -

pipes and gubbins -

first motorised valve -

second motorised valve -

 

[Softus]

thanks to the above two for helping.

You've been helped by three people, and hindered by one.

trying to take pics now but both the wife's and my camera are uncharged!

I would stop trying then, and charge one camera.

we turned the isolator off last night and the radiator is off. so presumably that means that the boiler must be firing itself up generally, doesn't it?

Could you be specific about which isolator?

Also, it's best to assume and presume absolutely nothing.

how's that happening?!

Is your boiler within the living space, or outside?

If outside, do you know whether or not there is a frost stat?

If there is no frost stat, and if your boiler is firing without any demand for heat via programmer and thermostat(s), then there is a wiring error or fault.

Has the system always behaved like this, or just started doing it?

 

[JamesUK]

respectfully softus, if i don't assume the boiler's firing up the how else is water getting hot?

isolator which shuts down the heating/water system.

boiler is inside the living space.

problem only seems to have manifest itself fully since we have started using the central heating.

 

[gasgeezer]

Would suspect dhw zone valve sticking and c/h zone valve partially letting bye heating nearest rad imho