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Hot water & Heating off but towel radiators always hot

(5 Posts)
Loumate666 Mon 31-Oct-16 11:35:30

I know that we have three Towel rads (non thermostatic) on the hot water loop so that when the hot water comes on the towel rads all get hot - great!

During the summer, I switched the rads off but now I've switched them on, they stay hot all the time

All new unvented system with boiler (Worcester Bosch Greenstar 35CDI) heating controls, wet UFH and valves summer just gone so should all be fine so any ideas what the issue might be? No other rads get hot

If feels like the boiler is circulating / pumping HW even though the HW / CH are both timed to off yet I can hear (and see via the flue) the boiler running . If I switch the HW on, I can hear the motorised valve next to the HW cylinder operating and a HW circulating pump start.

I've tried resetting the boiler but doesn't seem to be making a diff.

Maybe a stuck motorised valve somewhere (there are three)?

Cheers for any guidance


PigletJohn Mon 31-Oct-16 11:52:04

If the programmer is set to "off" on both HW and CH, then the boiler should not fire (unless there is an anti-frost thermostat).

However, motorised valves have a switch that can start the boiler. It is possible one might be at fault. But I would suspect a wiring error, especially if the system has recently been altered.

You say the rads stay hot all the time. Why so? Surely the programmer turns them off at night, or they go off when the room stat is satisfied?

TRVs do not turn the boiler off.

Loumate666 Mon 31-Oct-16 12:09:06


Programmer not set to off, set to timer but currently timed to off other than a couple of hours in morning and evening. I've just switched HW & CH timers to Always off (rather than timed) to see if that helps. Interestingly, I can still hear that the boiler is running (sounds like a pump running) although not producing anything from the flue so i don't think its heating anything.

Re rads staying hot at night (and during the day when HW is timed to off) - that's the problem, they shouldn't be!

My fear is that it could be a valve / wiring thing that's may have always been there and only just manifesting itself now that I've opened up the valves on the towel rads.

PigletJohn Mon 31-Oct-16 12:36:03

yes, it could be. The programmer should have turned off power to the boiler, apart from standby and overrun, so the problem sounds electrical, possibly wiring, or motorised valve. You need a heating engineer who's good at fault-finding.

BTW I have bathroom rad heated by the cylinder circuit, but a TRV to prevent excessive heating in summer. But that's not relevant to your problem today.

Loumate666 Mon 31-Oct-16 12:51:37

Ta PJ - I do indeed wish that I had TRVs installed on the towels rads - got them everywhere else!

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