Radiators not cooling

jaylockwood1978 · Mar 3, 2016

Hi, I have a tenant at a property and she's reported that she thought the wireless thermostat wasn't communicating with the boiler as the radiators seemed to be on all of the time, despite the program saying they shouldn't be.
my boiler is a Worcester Bosch Greenstar 28i junior and the thermostat a Salus RT500rf (I've heard they're rubbish but it's never given a problem in the last 5 years).

I popped round to check check and did all of the non-expert things I could....new batteries, checked programs, reset transmitter unit, turned receiving wall unit on and off. When I increase temp manually on wireless thermostat, the green light on receiving wall unit comes on, pilot light on boiler fires up. When I turn the temp down, the pilot light goes out, presumably turning heating off? All good I think. I then set all 5 programs to the minimum 5degrees to hopefully get the radiators to go off. Several hours later my tenant said the radiators were still hot.

i got a heating engineer out yesterday and he said the thermostat seemed fine and was doing what it was meant to do.

Tenant contacted me again today and she still thinks the thermostat isn't engaging with the boiler as the rads are still always hot.

could it be something else causing it and nothing to do with the thermostat?

Thanks in in advance for any help

Best · Mar 3, 2016

The heating engineer should be able to find where the constant power is coming from.
A lot of heating systems have motorised valves and they can be faulty and put power to boiler, despite programmer and wall stats being off.
But the engineer should know that and have tested any MVs. Get another engineer if you still don't get sorted.

jaylockwood1978 · Mar 3, 2016

Thanks for the speedy reply, appreciate it and I'll give them a ring now and mention that. Would a faulty MV valve still be issue if the pilot light isn't lit but the rads still hot? This is what's confusing me!! Hot water is on demand so doesn't need to be on or off on the boiler if that makes sense. Excuse my ignorance

Best · Mar 3, 2016

I am not gas qualified and some gas folk on here could clarify. But I think what might be puzzling you was the boiler cutting off with its own thermostat, but system is actually still working and circulating hot water to rads.
Very common to have a faulty motorised valve, so worth getting them checked first.

ShaunCorbs · Mar 3, 2016

Are all the rads hot or just one or two ?

and think it's a combi boiler best

jaylockwood1978 · Mar 3, 2016

Yeah, it's a combi boiler. The tenant is saying they're all hot so she's turning each one down individually with the dial on the side.
Spoke to the boiler engineer and he still thinks it's possibly the thermostat sending some signal to the boiler which is keeping it on?? I mentioned the motor valve and he reckons it not likely to be that as the water is really hot when tap turned on and if it's this motor valve diverting water wrongly to the rads, then that would affect the hot water from the taps and make it cooler? Hope I explained that ok.

Snyway ay he's recommended trying a new thermostat.