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Radiators hot even though the central heating isn't on - any idea why?

(31 Posts)
Loueytb3 Sun 07-Oct-12 22:03:33

The past couple of days I've noticed that our radiators have been hot even though the heating has been off for a while. It seems to be while the hot water is on as they go cool after the hot water goes off. Anyone have any idea why and do we need to get a plumber out?

Lynngarnham Wed 30-Aug-17 16:26:44

Hi, I have just posed this problem to the University of Kwa Zulu Natal, as I know someone who may be able to assist me there, however, I would think that not having control of gas central heating would not pass the building or health and safety inspector in Natal, and of course, one does not need central heating there.

Lynngarnham Wed 30-Aug-17 13:36:41

I tried to download a picture, but it won't go through, the switch was working when I first moved into the flat, when my neighbour re gassed her heating is when the problem first occurred, their is a heavy smell, and the heat hits you when you enter the maisonette, even though the bedroom is above the lounge. Thanks for your help from Lynn

PigletJohn Wed 30-Aug-17 12:42:43

No pics?

You are saying that your radiator is hot even though you have turned the knob to off? In the absence of photos I would guess that the radiator valve is faulty, though some can be set with max/min limit stops.

Lynngarnham Wed 30-Aug-17 12:02:19

my radiator has a turn switch which I need to turn on for heat, this is off, I live in a complex of maisonettes, two together, one has control of the central heating so if my neighbour switches it off, I cannot get heat. I have complained about the heat to the Landlord, and he replied that the neighbour would have to stand on a chair to change the settings, one does not need to be Sherlock Holmes to find someone else to stand on a chair and change settings.

PigletJohn Wed 30-Aug-17 10:57:26

What is off?

Show us pics of your boiler, pipes around the cylinder, timer/programmer and wall thermostat, and of the control knobs on your radiator valves.

Do you have your own gas meter? It is very curious to hear that your neighbour controls your heating.

Lynngarnham Wed 30-Aug-17 08:01:19

both of the pipes get hot, it is boiling hot right now even though it is off

Lynngarnham Wed 30-Aug-17 07:59:36

I live in a maisonette where the central heating is controlled by my neighbour, on Monday evening my bedroom was like an inferno even though my heater was turned off

PigletJohn Sun 25-Aug-13 21:55:48

see above.

how many of the pipes get hot.

you had the head replaced but maybe the ball is worn.

Ours was a valve which needed replacing.

The plumber said if that didn't work then he'd have to drain the whole system.

fayjames Sun 25-Aug-13 21:27:15

We have been having this problem. We have now had a new motorised head fitted and a new thermostat, this seemed to solve the problem for a couple of weeks, but a couple of days ago it started again :-( We know we could just turn the radiators off but we have spent a lot of money on replacement parts and labour, so really this isn't the answer. Does anyone know what route we can go down now, it is really frustrating, Thanks

PigletJohn Tue 06-Aug-13 16:13:54

have a look and see if you can find a 3-port valve on the pipes. It will have heat-resistant flex attached to it. Observe that the 3 pipes go into it in a "T" shape. It will probably be close to your boiler and/or your pump and/or your hot water cylinder. It will most likely be branded Honeywell or ACL Drayton.

Turn the HW on and the CH off and see how many of the three pipes get hot.

If only one of your radiators gets hot, and it is the one on the bathroom, it was probably intended to work like that to warm toweks in summer.

jschwei Tue 06-Aug-13 12:16:34

I have the same problem. When I manually open the valves with the arm, there is pressure so they should be working.

One of the radiators even gets warm when hot water on and radiator thermstat is turned off (tested with heat on and hot water off--radiator stays cold, so valves are working and hot water is somehow getting into this radiator).

I had a plumber come round who told me the valves are working. He then gave me the typical, "your plumbing was put in wrong, and radiators are on how water circuit" (despite 10 years of being fine!).

Is it possible there motor on the valves are working but the ball inside is letting hot water through?

davegriff Mon 15-Jul-13 09:56:20


Similar problem. Hot water only selected, heats the rads. Thought that the problem would be the valve, so changes the motorized 3 way valve (correctly ie A to rads, B to water). Problem still there.

Anybody help, please?

Loueytb3 Mon 08-Oct-12 10:07:58

Yes we've got a cylinder smile

PigletJohn Mon 08-Oct-12 10:05:28

P.s. we are all assuming you have a hot water cylinder.

If you have a combi boiler instead it will be the diverter valve in the boiler.

Loueytb3 Mon 08-Oct-12 10:04:33

Yes we can turn the rads off so that would be a solution in the short term. Hot water only comes on twice a day but I think it is on longer at the weekend so that was when it was more noticeable. Its not so much of an issue during the week.

PigletJohn Mon 08-Oct-12 09:58:57

It may cost you extra money since you will be heating the house more. Do you have thermostatic radiator valves? If not you can turn off the rads with the knobs on their valves.

Try altering the programmer timings so the HW only comes on twice a day, mornings and evenings.

Loueytb3 Mon 08-Oct-12 09:47:54

Thanks. Can it wait a week or two to be fixed?

PigletJohn Mon 08-Oct-12 00:08:00

yes, it will be the three-port valve, and it happens when the cylinder is calling for heat, and the valve allows some of the heat from the boiler to go to the rads instead of to the cylinder.

If you had it done for £50, it was almost certainly just the motorised head that had failed (this is the squarish box on top) rather than the rubber ball in the brass valve worn out. The motor can be changed without draining down as it is detachable on all but the oldest models. You can also manually operate the lever on the side of the head, if the motor fails.

The entire 22mm valve and head costs about £80 depending on brand and supplier. Honeywell and Drayton are good and widely used.

There is a faint chance that it is caused by a wiring fault, especially if some inexpert person has recently fitted a new programmer or tinkered with the wiring.

If you have 28mm piping (not common) it will be more expensive.

Pochemuchka Sun 07-Oct-12 22:45:57

Another one agreeing with oldandcobwebby.

Just had the valve replaced for the same reason. Heating off, hot water on = red hot house not controlled by thermostat.

Took the guy about 1 hour to do.

Startailoforangeandgold Sun 07-Oct-12 22:37:14

Our bathroom radiator comes on with the hot water. Very handy for drying towels.
I'm told by he who knows everything (DH) that the system needs one radiator that can't be switched of to function correctly.

Way2Go Sun 07-Oct-12 22:23:33

If the plumber says he has to drain the whole system make sure he puts isolater valves either side of the diverter so that if it fails in future you wont have to drain the system.

You can't have enough isolation valves smile

I am not a plumber though so I might be talking shite.

Loueytb3 Sun 07-Oct-12 22:21:57

Its a new problem so I suspect not due to botched plumbing but to something going wrong, although time will tell I guess. The upstairs radiators are hotter but the ones downstairs are still warm. Glad it sounds like it could be easily fixed - can it wait a few weeks or is it something that we need to sort out asap?

We are waiting on a planning appeal which we should know about in 10 days time. If we win, we will be replacing the heating system anyway.

Way2Go Sun 07-Oct-12 22:18:29

oldandcobwebby is probably right. It's a common problem. You need one of these.
They have a manual override switch so you can use that until you get it fixed. They are cheap but buy a good brand.

angel1976 Sun 07-Oct-12 22:14:57

RightUpMyRue Laziness makes a good reason too! grin

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