Problem - Thermosatic Radiator Valve

crosstownk

Ok - I turned on the heating for the first time last night. Some rads were a bit cool so I bled them sucessfully. However, one is still stone cold despite profuse bleeding. I think the TRV may be jammed. Any ideas on how to free it? I could get a new valve but I'd rather avoid the hassle of draining down the system.

Another rad seems to be on full, irrespective of where the TRV is set - any ideas here?

JamesM

crosstownk wrote:

Ok - I turned on the heating for the first time last night. Some rads were a bit cool so I bled them sucessfully. However, one is still stone cold despite profuse bleeding. I think the TRV may be jammed. Any ideas on how to free it? I could get a new valve but I'd rather avoid the hassle of draining down the system.

Another rad seems to be on full, irrespective of where the TRV is set - any ideas here?

Not sure about the one that stays on, but if you remove the head from the cold one and gently tap (with a light hammer) the top of the pin in the centre of the base, it should pop up. If not, pull up the pin with a vicegrips and then some gentle taps usually loosens it. When it is loose, you will be able to push it down and it will spring up again.
Make sure that the valve that does not shut off is free as well - this might be the problem.
Jim.

Do-more

Has happened to me in the past, I held down the pin with a vice grips and sprayed in WD40. If you are still having problems swap over the top part of the TRV from a rad that you know is working OK, you will then be able to figure out which part of the valve is defective. So far I have never had to replace the bottom part of any TRV, but I have replaced a few tops.

crosstownk

Good stuff - I'll try all that tomorrow.

Thanks for the replies.

crosstownk

Cheers - once I tapped and pulled the pins both rads are behaving normally and TRVs seem to be operating correctly. I sprayed some WD40 to be sure. I'm going to clean and 'service' the rest of the TRVs now - in the hope of avoiding further problems.

Once again - Thanks!

tomsav

Hi, I'm having the same problem with a radiator that is cold even though there is no trapped air when I bleed it. All other radiators are fine. It's a "TRV 2 Way Myson". I want to try the swap idea proposed here to see if it is broken but my question is this: Can you take this off without having to close off and drain the raditor? Thanks.

crosstownk

You should be able to remove the thermostat bit. Look below the plastic piece - there should be a circular grip with a screw. Loosen the screw and the thermostat should pull up and off. Then you will see the pin that was mentioned above. A bit more info here > http://www.myson.ie/install/TRVTEC.pdf or here > http://www.myson.ie/pdf/ppv.pdf

tomsav

Thanks a million crosstownk. Was able to remove it and compare it to one thats working. The pin from the top part is permanently down and won't stay up. Need to replace it. Thanks again.

crosstownk

Do what I did - pull the pin up with a pliers and then spray some WD40 on it for good measure.

ddonlon

Can anyone recommend good TRVs to use I tried some a few years ago and could not get them to work properly they were either fully on or fully with nothing in between I dont mind what they cost if they will do the job

crosstownk

Mine are Potterton Myson. They are quite old and all are working fine now. The only problems I had were the two mentioned above, and they were relatively simple to fix - so I'd have to recommend them.

Gwynston

Are there any DIY-lite TRV's available?
i.e. TRV's that can easily be installed by a DIY novice like myself (plumbing-wise)? I'm looking for something that will just screw on and replace the existing valve without having to redo compression joints.

I guess the system would still need to be drained anyway for the job?

crosstownk

You can replace the thermostatic head fairly easily, but the valve will have to be removed from the rad and pipework. So you'll have to drain down the system, unfortunately.