Last year I moved into a 7 year old house that has gas central heating. I never noticed before as it was summer and didnt have the heating on much but over the winter ive noticed that no matter what setting the thermostat is at, the heating always comes on full blast, so hot that you cannot touch the radiators for long. Even if the thermostat is down at its lowest setting (10 degrees I think). Thus I got a HUGE gas bill there :( Would this be likely to be a thermostat wiring issue? Its a dial one with Scottish Gas stamped on it. I plan to buy one of those digital ones, are these any good
yes the thermostat does click around the 25-26 degree mark but it doesnt seem to switch the radiators off,theyre still red hot. id need to go into the garage to check to see if the boiler switches off. As i said before, even with the thermostat down at the lowest settings the radiators remain on. I should turn down the boiler one though.
Faulty wiring Faulty thermostat Faulty electric valve
Do you have a timer to control both the heating and the hot water? If so, if the heating is off, does the heating actually go off? Even with the hot water on, is the heating off? If so, it is probably the thermostat, if not, then it is probably the electric valve.
When you get it fixed you may like to look at one of these - offers different temperatures for different times of the day:
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agree with one of the other replies - it could be the motorised valve. Mine was allowing heat into the CH Circuit when it should only have been heating the water.
But surely it could simply be that the boiler's thermostat is set to Max?
My now ancient boiler (all of 12 years old) has three switch positions: max, off, and min (in the order of how you flick the switch). My plumber told me two years ago (when I had a new control system fitted) that I should "never need to have it on Max" and indeed he has been proved right. (I left open the question of why there needs to be a Max setting at all, then, eh?)
On 16 Feb 2006 01:48:29 -0800 someone who may be snipped-for-privacy@yahoo.com wrote this:-
They will be for a while. They cool down to room temperature over a period of say 30 minutes.
None of us are going to do this for you.
To add to what the others have said, can you turn the water heating off at the programmer and just have the heating running? If you can then you should find that the boiler is running and the motorised valve moved to put all the water through the radiators with the thermostat turned fully up. If that is the case then turn it down to the minimum setting. The boiler should now have stopped firing, though the pump may well still be running. If the boiler hasn't stopped then the most likely cause is a faulty thermostat.
In a typical reasonably modern system you have a series of switches in a chain.
The time clock drives the master thermostat and that drives a motorized zone valve, the output of which drives the boiler.
All of these have to be on to fire the boiler up..if the thermostat or zone valve sticks on, you will have overheating of the house. If the timer is stuck on its simply 24x7 heating..but still regulated by the stat.
The boiler itself merely has a thermostat - in your case with two positions - to control the actual water temperature coming out. This is more a safety feature than anything else..to prevent the boiler - er - boiling ? :-)
Its easy enough to check the thermostat - you should hear it clicking as you move it above and below the current room temperature. If it clicks its 90% certain its not stuck.
Checking the motorized valve is not so trivial..you need to get someone to fiddle the thermostat and then check to see if its moving ...you can hear it do this. Another possibility is to open up the thermostat and actually disconnect the wires..usual safety precautions apply - if this still fails to stop the house heating the motorized valve is definitely at fault.
Two things go wrong with motorized valves - the motor and the valve.
Most of them can be disassembled without draining the plumbing to the point where you can check the motor bit and also check to see if the valve is actually turnable. If the valve turns OK but the motor doesn't work, then get a new motor assembly. On line places sell em.
If the valve has jammed its drain down time and a new valve..
The thermostat doesn't control the actual heat of the rads but how long they are on for until the room reaches the temperature set. Think how an electric fan heater works - it's the same principle.
If you can find the pump, you should be able to hear it run if the thermostat calls for heat and stop when it's not. Of course the pump also heats the hot water cylinder - if you have one - so make sure that's hot first, or switched off. If the pump is running continuously regardless of the thermostat setting it needs investigation - and don't rule out the possibility it has never worked due to incorrect wiring etc.
If the stat clicks at 25/26, thats how hot the place is. Horrid, and costly.
Others have explained how to find the problem. As an instant temporary tamer, you can turn the water temp stat on the boiler to minimum. Wont fix it but will tame it until its done.
Be careful doing that. If you turn it down too far you can get condensation of water from flue gases. In a condensing boiler, this happens byt design and improves efficiency. In a conventional boiler, it will result in accelerated corrosion of metal components.
i just meant I was gonna turn it down a little bit : )
Can i ask one more thing. Now that I have purchased one of these programmable ones and assuming i can fit it ok, does this mean that i should now have the central heating on "ALL THE TIME" at the timer control and regulate it using the new thermostat? Is that the normal thing to do?
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