Central heating oddity - weird radiators

[manalishi]

Any CH-savvy folk out there? For the last couple of days, a couple of the radiators in my house have warmed up (to piping hot) even though their Honeywell temp-control valves are turned all the way down. I can turn them back off by turning them all the way up and then all the way down again.

Meanwhile the other raditors that are turned up warm up just fine, and those others that are turned right down stay cold.

 

[kwakdonut]

Sounds like the TRV's are jamming open - try exercising the valve (as you appear to have done already) a few times and check again. You might have to change them - not a hard nor expensive job for a competent DIY'er.
A GENTLE tap with a wooden or rubber mallet on the valve may help but normally the answer is to change them.

 

[davidjpowell]

Hit them! - seriously I think some of the thermostatic valves jam up over a period of time, and need a (gentle) knock to free them up.

 

[Will]

Hi Barry,

I agree, does sound clearly that the valves aren't being allowed to close when they are up to temperature, either by way of jamming/deposits or perhaps the thermostatic part not operating as it should. What brand are the valves and do you know how old they are?

Will

 

[kwakdonut]

During the summer, I open all the valves to '5' or Max - this helps to avoid this problem!!

Yes, old ones can jam but I had one that was a year old that did too.

 

[manalishi]

Thanks all.

I'll try the 'gentle mallet' thing first. Luckily I have a rubber mallet left over from the BigDug benches I bought.

Will - they're Honeywell - not sure of age (>5 years, I'd guess). Only 2 out of 8 are playing up.

kwakdonut - useful tip, I'll do that 5/Max thing next spring/summer. May try to DIY it if they then continue to play up.

 

[kwakdonut]

You're welcome!

 

[verytalldave]

I wouldnt advise hitting the valve stems with anything. Simply "exercise" the valves by turning between the maximum and minimum settings a dozen times or so. If that doesnt coax them into life, then replace the valves as has already been said.

BTW.........at least one of your radiators should NOT be fitted with a thermostatic valve (usually the lounge). This ensures that the pump does not work against a closed system at any time.

 

[kwakdonut]

BTW.........at least one of your radiators should NOT be fitted with a thermostatic valve (usually the lounge). This ensures that the pump does not work against a closed system at any time.

Absolutely - the one we have is actually the radiator nearest the thermostat

Good luck!

 

[Dieselman]

At a guess your system is short of anti-corrosion agent thus the valves are sticking.
Drain some water out and add agent then allow to refil.

 

[crockers]

Our non therm rad is in the hall opposite the main thermostat......strange I thought as it will cut out the whole system.....our last house had it in the bathroom...

I've found hitting the stuck valve with a shoe has helped in the past.