TRV stuck open

[ikaya]

Hi, I've got a radiator which will cool down only when I close the valve opposite the TRV. It makes no difference if I screw the TRV down as far as it can go, which is past the freezing icon on the top by the way. All the other radiators are working well and their TRVs seem to let me adjust the room temp effectively. They were all installed about 10 years ago when I had a new boiler put in.
I've not found any other similar problems when I searched and would appreciate some help.
Thank you
Ikaya

 

[oilman]

It's done ok to last 10 years. Replace it.

 

[moggridgeplumbing]

the valve at the other end of the radiator to the TRV is the lockshield valve, which should not need adjusting unless you happen to be balancing your central heating system.

The problem you are having with your Thermostic Radiator Valve (TRV) is either the head is not screwed on correctly, or the head is stuck in the open position. I first suggest you remove the head - there is usually a holding threaded ring underneath it. Once removed check to see if there is a pin on top of the valve, which should push up and down. If that doesn't seem to be there or is stuck in the open position, you will need a new valve. Also if the holding threaded ring is cracked you will need a new valve, but check these things out first.

I hope this is of help.

 

[ikaya]

Thank you moggridgeplumbing, I shall have a look at it and let you know the outcome.
My only concern, however, is whether I will release the water by undoing the knurled ring. I'm not doubting your advice, just don't want to have a flood over the holidays.
ikaya

 

[moggridgeplumbing]

No the knarled ring only releases the TRV top - the valve is sealed.

 

[ikaya]

Hi Moggridgeplumbing. I took off the top of the valve and the pin appears to be stuck. So, a new TRV is indicated? Does that mean the whole system has to be drained down?
Many thanks again
Ikaya

 

[moggridgeplumbing]

Not necessarily. Do you have a sealed or open vent system?

 

[ikaya]

How do I know?

 

[ikaya]

Hi moggridgeplumbing. Apologies for my ignorance, I've looked on the net and found that my system is open vented. It has a header (F & E?) tank which tops up the water level. Do I have to drain it all down for one TRV?
Thanks again for your help.
Ikaya

 

[dcawkwell]

Hi moggridgeplumbing. Apologies for my ignorance, I've looked on the net and found that my system is open vented. It has a header (F & E?) tank which tops up the water level. Do I have to drain it all down for one TRV?
Thanks again for your help.
Ikaya

Yes.
In my opinion I think TRVs are more trouble than they are worth.

 

[moggridgeplumbing]

It can be done without draining down the system but unless you are a plumber I suggest you drain down the system, rather than take the chance of a flood.

 

[ikaya]

Many thanks moggridgeplumbing for all your assistance, much appreciated.
All the best
ikaya