Central Heating Thermostat

username9876

My central heating is constantly on despite the thermostat being set to 10 degrees. I have managed to cool the house down by turning a switch on the boiler to 0. Rather than get an engineer out I want to change the thermostat first, but I have never changed one before. Is it advisable to try this myself?
My current thermostat is a Honeywell T40 and I will replace it with a Honeywell T6360. I have a separate digital unit that allows me to put timers on the heating and water.

keystone

Your roomstat is only a very simple switching device. I think you may have a problem with your diverter valve and you should check that this is working properly first.

Cheers

username9876

Any idea how I can test this?

keystone

Lets assume you have a Y plan with a three port valve (dangerous of course, to make assumptions so perhaps you could describe your system later on)

First make sure boiler is on for both DHW and CH. Turn both roomstat and tankstat down to minimum. Turn up boiler stat to around 3 - 4.

Take the head off the diverter. Get someone to turn up the roomstat with the boiler on. Does the motor work? Get them to turn the room stat back down again. Does the head reset?

Do the same with the tankstat. Does the head operate correctly for that? If the answer is yes in both cases then its not the head. If the answer is no then its the synchron motor inside the head.

Check that the valve itself isn't stuck by manually operating it. It should move freely. If it doesn't then there's carp in it whether or not the head needs to be replaced.

Cheers

username9876

That's too much tech talk for me. The system has now returned to normal, for the moment, so I think I'll get an engineer in next week. We're in a new house so I'll get a service done too.

macman

If the room stat is working then you should hear it click on and off as it passes through the ambient temp setting. Does it?
Have you tried removing the cover and just blowing any dust and dirt out?

bengasman

username9876 wrote: »

Is it advisable to try this myself?
My current thermostat is a Honeywell T40 and I will replace it with a Honeywell T6360.

If you have to ask, the answer is: no.