Thermostatic radiator valves

[Nigel Watts]

Thermostatic radiator valves seem to be one of those gadgets we are all encouraged to fit to help save the planet, but how good are they?

My house was completely rewired and replumbed about seven years ago and all radiators fitted with these valves. In virtually every case none of them can now be fully turned off. Even in the off position the radiators warm up - not as much as when turned up admittedly, but enough to waste energy by unnecessarily heating rooms which are not in use.

What is the life expectancy of such devices? Are some better than others in this respect? Should I replace the lot?

 

[worms]

Interesting! In my case, some of the radiators have never really been properly controlled by the rad valves due, I think, to the position of the valve relative to the radiator and the cross flow of cold air over the valve. Swapping the valves with others from radiators where they work properly makes no difference. It seems to be a problem for my radiators that are on internal walls where air-flow is along the radiator whereas radiators that are properly positioned under a window are fine.

Others that seem to come on when they shouldn't I have always put down to the temperature being colder than I imagined, triggering a frost guard reaction.

 

[JoceAndChris]

The heating is off here most of the time, making for an invigorating ambience as you well know, but when the Rayburn clicks into life the thermostats do a marvellous job of keeping the rads bracingly tepid. :roll:

 

[Pford75]

Most TRV's do have a 'frost' setting...which contrary to the name kicks in well above freezing. It could be that the room is sufficiently cold that this is the problem. This is why you should never remove a rad and rely on the TRV as the shut-off for the pipes

 

[middi]

Good quality rad valves are extremely good and exellent value for money and easy to cut off heating from any rooms. That is the plus side

The minus side:- They need patience and trail and error to set them at the desired temp within a room as they only have a " balance" didget position you can follow. Once you have mastered what position(s) is best for your situation they are brilliant.

 

[skier-hughes]

what happens if I turn down the stat on the radiator that's in the room with the thermostat for the whole system, as we now have a few rads with their own stats and most without?

 

[Penners]

what happens if I turn down the stat on the radiator that's in the room with the thermostat for the whole system, as we now have a few rads with their own stats and most without?

It's not a good idea to have a TRV on the rad in the same room as the roomstat, Graham. You're better to leave that rad with just an ordinary valve.

You can then (by trial and error, as Middi says) establish the correct relationship between the roomstat and that radiator to ensure that the whole house heating is switched on and off appropriately.

 

[Penners]

Most TRV's do have a 'frost' setting...which contrary to the name kicks in well above freezing. It could be that the room is sufficiently cold that this is the problem. This is why you should never remove a rad and rely on the TRV as the shut-off for the pipes

I agree with Pford that the frost setting could be the reason why Nigel's rads are still getting warm, despite apparently being shut off.

But all the TRV's that I've seen also have an OFF position beyond the frost setting. Sometimes this is protected by a button that you need to press to get beyond the frost setting; sometimes this last quarter-turn or so is just stiffer than the rest.

But you should be able to shut off the valve reliably.

 

[worms]

But all the TRV's that I've seen also have an OFF position beyond the frost setting. Sometimes this is protected by a button that you need to press to get beyond the frost setting; sometimes this last quarter-turn or so is just stiffer than the rest.

But you should be able to shut off the valve reliably.

We have a radiator in a lean-to, mainly-glass, sun-lounge and on cold nights in winter the radiator will warm up - even with the valve beyond the frost setting and firmly in the off position.

Also, the frost setting must be somewhere about 7 or 8 degrees as our hall radiator (which we never use, but keep on the frost setting) will come on at times through the winter when the house is cold but nowhere near actual freezing point.

 

[Penners]

TRV's are quite prone to faults. Have you taken the top off and checked that the pin can move freely?

If so, and if you still can't get your TRV to close completely, you may have one of the old type (I believe now superceded, but not sure) where there is no actual OFF position. You should still be able to shut this off completely by buying a shutoff cap for it. You unscrew the top mechanism from the valve and substitute the shut-off cap which depresses the pin fully.

 

[Andrew Bodenham]

Nigel,

In order to get full shut-off the sensor head needs to be securely attached to the valve body. I've encountered several valves in client's houses where the sensor head has become loose or has been poorly fitted, leading to the activation pin in the valve not being fully depressed. Worth having a good look at how your valves are assembled.

Some valves also have mechanisms for setting upper and lower limits on the temperature scale. If this has been done on yours it would explain why you can't obtain full shut off.

I've fitted a variety of valves in my own house and client's, and I've never encountered any problems with them, except with some of the very cheap ones. I'm constantly surprised at how well they function; it seems all wrong to me to site a thermostat right next to the heat emitter. But work they do.

What brand of valves do you have?

 

[Nigel Watts]

This is all getting a bit technical but I will have a look and try to find the make and the pin you and Penners talk about. The other problem these valves give is hydraulic hammering when the value is closed, the only solution to which seems to be opening the value a little.

 

[MdB]

This is all getting a bit technical but I will have a look and try to find the make and the pin you and Penners talk about. The other problem these valves give is hydraulic hammering when the value is closed, the only solution to which seems to be opening the value a little.

Ahh, this might explain it. Do ALL of your radiators have thermostatic valves? If so, when the all shut off, the pump pushing the water around is pushing against a closed pipe and this can push the pressure sky high. This high pressure can create all sorts of whistles and hammering depending on exactly how closed the valves are. Opening one of the valves, releases this pressure and stops the noise.

The simple solution is to remove one of the thermostatic valves from one of your radiators (I believe they just unscrew exposing the pin that has been talked about). This should ideally be near to the main electric thermostat which switches the boilder on / off. The downside of course is that this radiator will always be on when the boiler is on which can cause over heating and / or the boiler to go off before all the room are heated.

The better solution is to have your pipework fitted with a radiator bypass valve such as this:
http://www.uk-plumbing.com/honeywell-du145b-22mm-automatic-bypass-valve-p-1372.html

I'm not a heating expert so some of the above might not be completely correct.

This might help on the understanding on how the valves work:
http://en.wikipedia.org/wiki/Thermostatic_Radiator_Valve
http://heating.danfoss.com/PCMPDF/trv01.swf

 

[ljn]

I had 15 thermostatic valves fitted. Posh brass ones with fake wood detail.
Open or closed, the rads remained stone cold or in some cases, just slightly warm at the bottom near the valve.
To heat the radiators, I had to completely unscrew/remove the whole valve. Otherwise they would remain stone cold. That would get them really hot. Once the room is warm, remember to replace the valves (turning the rads off).

I also have one modern thermostatic valve- of the chunky plastic design with big numbers- feels like it might not last it's first year of life an never actually turns off- always warm.

I spoke to the company and they said it could be a "bad batch" where the steel pin that regulates the flow was too long.
As draining the system and returning all the valves was not a practical option, they advised removing 1 or 2 millimeters of the pin with an angle grinder.
My plumber suggested cutting off the plastic pin on the tap side (the part I was taking off).
It worked. Now non of them turn off properly, but at least we have heating.

I wish I could have had a simple sturdy tap style valve I could turn on and off, or leave in any position in between.