When I asked British Gas to install us a new boiler, I thought I’d be getting some quality work carried out. This was quite a few years ago BTW.

It has been a long, long succession of failures. If I had a gun I’d have shot them all by now.

Anyway, the latest issue I have is that I’m absolutely convinced the thermostat is a load of bobbins. If I turn it down, the boiler just carries on running away quite cheerfully heating the house up to the temperature of the sun. Quite often I have to turn it on and off, turn it down, turn it up, wait a bit and then maybe, it’ll work.

So I’m going to replace the thermostat.

Do any thermostats work or does it need to be aligned with the boiler in some way?

I quite fancy one of them thermostats with an LCD display, recommendations?

Most are compatible but may need the back part rewiring if I understand properly from when I looked into it a few months ago. It’s not a big job for the relevant skilled person my plumber told me when I asked.

If it’s any consolation, my thermostat probably came from the same batch as yours – the house is either way too hot or way too cold.

I got my sparky to fit a salus RT500 while he was here doing some other work. Took him about 20 mins and seems to work great. wireless control module.

Thats on a Worcester 28i junior RSF. the worcester equivalent was about £150, this was about £30 from amazon.

it might not be your stat that is the problem…

over the weekend our own heating system refused to turn off (boiler kept burning). a bit of googling showed that the 2x automatic honeywell diverter valves we have can cause this if they stick. Bit of ‘persuasion’ and it’s now back to normal.

If you have them – check your diverter valves. Ours are little silver boxes connected in pipework located near the electronic control panel for DHW/central heating. If the little external lever can be moved by hand with no resistance it’s a sign the valve is stuck. If you move the external lever on the valve from ‘auto’ to ‘manual’ and it moves back to ‘auto’ by itself chances are they are working and it’s another problem.

just an idea – I’m certainly not a heating engineer so might have it wrong

You can usually hear thermostats click on and off though so if the boiler fires up or off as you click the thermostat on and off then it’s a thermostat problem. I think a lot of them just stick so that they have to signiificantly over/undershoot the desired temperature to turn on/off.

Wireless you say? We have a vaillant boiler and wireless stat/programmer. The stat/programmer can be plonked anywhere but there’s a transceiver that needs to be wired to the boiler. In our case that amounts to a positive and negative wire, at 24V I think. Its all pretty simple.

Surely there’d be a third switching wire at a minimum?

I’d expect, and I appreciate this could be unreasonable, that the thermostat would have an off switch. When I click that (and currently this involves sliding the lever round to indicate that the timer settings are to be ignored, sometimes it stops the boiler quite quickly, other times nothing at all. Also if I turn it down it sometimes works. I’m reasonably convinced at this stage that it’s the thermostat itself.

Some more googling has suggested though that the wireless could be the problem. We have cordless phones in the house which are apparently prime candidates for this…. It’s close enough to the boiler to run a wire, not sure if this is possible for our boiler, I’ll do some more checks.

Thanks all.

Have you replaced the batteries in the thermostat or do they need replacing? When you do that, you have to link the thermostat to the transmitter on the boiler so they connect and work together.

Think any new thermostat will be supplied with a new transmitter.

Yep, replaced the batteries a number of times. The boiler has a blue light on the front that flashes when they two are talking and that’s always going.

Can’t remember as we have a Worcester in other house but think ours only flashed blue when they were talking (heating being on and running), not all the time. If it is flashing all the time that may be the problem.

Which thermostat have you got at the moment?

Surely there’d be a third switching wire at a minimum?

Nope, its a bus system iirc.

Don’t know what we have right now. It has a circular dial with DIP switches on it and a couple of levers. Clicks like a clock.

Know the one you mean, its the same as ours.
http://www.worcester-bosch.co.uk/homeowner/boilers/boiler-controls/which-controls-go-with-my-boiler/mt10rf-mechanical-thermostat
Was told of a few issues the digital ones had a few years ago. Mate went through about 3 or 4 from new getting it to work while our clock one worked straight from new.

Bit of digging and it sounds like a common fault on those stats.

The one Skiprat refers to is the Mechanical version, so its not Digital, the if you want the digital version, try this one (as long as your boiler is a Greenstar model)
http://www.directheatingsupplies.co.uk/products/pid_27379/Worcester-DT10RF-Digistat-7716192052.aspx

Otherwise, you’d be better off going for an aftermarket one like a Danfoss model which is what Ive got and it simply works with no fuss:
http://www.directheatingsupplies.co.uk/products/pid_35248/Danfoss-Randall-TP5000-Si-5-2-Wireless-Programmable-Room-Thermostat-with-RX-1-Radio-Frequency-Receiver.aspx

The worcester site is usually very helpful to identify what youve got. But almost any aftermarket controller/stat will work as long as you get the type right (ie, Single or Twin channel)