Now the weather has cooled down slightly we’ve noticed the radiators aren’t coming on. Anyone able to offer advice? My wife is wearing two jumpers and threatening divorce if I don’t sort it out?

We had the boiler replaced a few years back. There is hot water and the underfloor heating is working in the kitchen (fed by the central heating). But the radiators aren’t getting warm.

I’ve bleed the radiators, repressurised the system, reset the boiler, turned it off and left it half an hour, cleaned out the Fernox and still no heat.

As the underfloor heating is working I’m assuming the thermostat is to blame – is the only way to test this to buy a new one and swap it over?

Any thoughts if it could be anything else? Diverter valve?

Is it get a plumber out time (or an electrician)?

what kind of thermostat?
Wired analogue?
Wireless digital with a relay near the boiler?
What boiler control panel?
Is UFH on same CH circuit with manifold and valve?

Thats a big piece of string you’re trying to measure there…

Is it get a plumber out time

Given what you’ve done already, I’d say so, if only to put it all right again 🙂

Thats a big piece of string you’re trying to measure there…

How do you know? 😉

Sticky motorised valve?
Take the head off and see if it turns when not connected to the valve (adjusting the thermostat to switch heating off / on) If it’s working, trying turning the valve manually.. it should move without much effort.

Jeff

Central heating on in September???

what kind of thermostat? Siemens RDJ10RF
Wired analogue? Wireless
Wireless digital with a relay near the boiler? Yep – although I’ve switched off the thermostat and overriden the control to run the boiler – still nothing
What boiler control panel? Worcester Greenstar 38CDi
Is UFH on same CH circuit with manifold and valve? Yep.

Jeff – take the head off? This could get interesting… how?

IHN – I’ve only got a few spare bits for the plumber to put back. 😉

I know naff all about UFH, is it feed from the heating circuit or water?
Regardless, my first port of call for central heating malfunctions is always checking the diverter valve. And it’s usually buggered.

Is UFH on same CH circuit with manifold and valve? Yep.

I’d be looking at the valve that controls distribution from the CH circuit to the UFH.

If the boiler is pumping CH water to the UFH, then the call for heat is working correctly, and its either whatever controls the diverter valve electronically (boiler? thermostat?) or the mechanics of the diverter valve (stuck, knackered).

Can you fit a wire across* the thermostat connections (well, the relay connections) to simulate ‘always on’? That would narrow it down to the thermostat or relay at least?

* see how I resisted mentioning jumpers?

It’s common for synchronous motors to go phut. They aren’t cheap and most suppliers won’t allow you to return them when the problem then turns out to be the actual valve sticking.

It’s common for synchronous motors to go phut. They aren’t cheap

They are pretty cheap, unless you go for the full branded version. Worth a punt if you know the boiler is OK before you start swapping out thermostats, or entire motorised valves.

Remember to turn the power off before you go poking around to get the motor out.

Cheers for the advice – worked through it and was the motor on one of the actuators. £16 from screwdix and back up and running

Also installed a Nest thermostat while I was there.

Sticky motorised valve?
Take the head off and see if it turns when not connected to the valve (adjusting the thermostat to switch heating off / on) If it’s working, trying turning the valve manually.. it should move without much effort.

Jeff

My thought too, as my hot water is doing this. Unfortunately I appear to have an ancient Drayton valve that no likey having the top removed .. might be a drain and replace job 🙁