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TRV valve problems?

Postby jackthebuilder » Mon Jan 05, 2009 12:11 am

Greetings and a good New Year to you all!

I promise I've had a good look through lots of postings, and so my apologies if this has already been answered!

PROBLEM: one stone cold radiator out of 15 in the heating system.


Shut off most of the other radiators to try and force water through. No joy.

Bled all radiators in system. No joy.

Removed top of TRV on offending radiator - it's a WESTHERM - maybe 15 years old? - as are all the others (apart from one - see below) which work fine. (And, yes, there are 2 radiators without them, and with no easily-switchoffable valves.)

The valve top comes off easily - push down the wee pointer that indicates on the 1 to 5 scale, then the head unscrews. Inside there is a section, about 20 millimetres square with rounded corners, that you can push down about 2 millimetres and springs back up when you release the pressure. The amount of travel and 'springiness' seems identical to the TRVs that work fine.

I've noticed the debate about installing TRVs on flow or return. Conclusion seems to be that it doesn't matter with modern valves, but might it make a difference on the WESTHERM? I've a feeling that the offending one could be on the return - might that make a difference? Is there something inside that could still be stuck even though I have movement in the plunger? I did try the 'light tap with a hammer' as well - no joy.

And the room is quite cold as well, so it's not shut off because it's warm enough!

While I'm on, one of the other valves doesn't work because the wee black plunger inside the head of the TRV (about 5mm diameter and 25mm long) iis missing - any idea where I could get a replacement?

Thanks for reading all this - hope you can help.
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Simply Build It

Postby stoneyboy » Mon Jan 05, 2009 5:27 pm

Probably easiest to replace the TRV with a modern 2 way model, you will then have a spare plunger.
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Postby htg engineer » Mon Jan 05, 2009 7:22 pm

Possible blockage ???

If the rad still doesn't heat with the TRV head removed and all other radiators turned off there's either an airlock, blockage or lockshield valve is closed.

htg engineer
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