Central Heating Thermostat

recovering_spendaholic

Hi - I had a new central heating system, including new radiators, installed in April, and I have rarely had the heating on until this last couple of weeks. If I have the thermostat set at below 20 degrees then the heating never comes on at all, and the house has been freezing this last couple of days and the house thermometer says it is 12 degrees. However if I turn the dial to 20.5 degrees then the heating comes on and in about an hour the house it way too hot and I have to turn the heating off again. Do you think there is something wrong. Before I got this new system I had a 23 year old system which only had high and low on the thermostat and it worked fine and the house never got opressively hot like it does with this!

baldelectrician

what kind of stat is it, where is it and is it near a draught?

Mr_Meanie

Do all your radiators have thermostic valves fitted? if so they are the ones you should be adjusting so the temperature is correct room by room, the room thermostat only knows what the temperature is in one place and turns the whole system on or off depending on how hot or cold it is whereever the thermostat is sited.

Mikeyorks

recovering_spendaholic wrote:

Do you think there is something wrong.

Yes .. I think you've got a faulty thermostat;) Could be the unit - or some dirt left in it if someone's chased a cable above it during the new installation.

If you're manually having to put it to 20.5 to get it on - then it stays on, there's something wrong with it. Still insured?

The thermostratic valves aren't going to control much individually .. if the central stat isn't bringing the system in.

YorkshireBoy

Many (most/all?) quality 'mechanical' room thermostats have an 'accelerating' resistor incorporated in the unit.

In order to make use of this feature (which improves the sluggish performance of this type of 'stat with low current loads), a neutral connection is required at the stat - in addition to the switch-feed and switch-wire.

Maybe your installer only cabled the 'stat in twin cable, and so couldn't connect the accelerating resistor?

david29dpo

bin it and get a programable one. i only paid £24.

Mutton_Geoff

Sounds like a duff thermostat to me. On a recently installed system, you should have thermostatic valves on all the radiators except one (usually bathroom or small room). Most plumbers follow tradition by then also installing a room thermostat but these defeat the object of the radiator stats and will shut off the heat when the demand is met only at that location, hence your experience of the rooms being too hot or too cold.

If you feel up to it, I would certainly recommend balancing your radiators making the system much more efficient and moneysaving. Most plumbers don't bother as it's a time consuming exercise and so they tend just to wind closed a couple of the radiator valves nearest to the boiler. Follow the techniques in the link and you'll soon have the whole house nice and warm with the system running at maximum efficiency.

gzed

david29dpo wrote:

bin it and get a programable one. i only paid £24.

i have an old boiler and thermostat and the latter has been playing for a few years now and I basically have the same problem as mentionned in the first post. I know that sometimes the thermostat is "buzzing" and if I gently knock on it it will stop.

>>DAvid29dpo: what kind of thermostat did you install, from where?
Thanks

My radiators all are supposed to be regulated I think, but it has always been an ON/OFF situation, but as long as the central thermostat was working this was fine.