Failed TRV

[fattony]

Hi

I moved house a year ago, 2 radiators didn’t warm up much last winter, reconfigured the space and swapped these 2 for a larger single radiator.

Filled up and a number of radiators wouldn’t warm up, put x400 in wondering if there was a blockage but eventually worked out that 8 of the trv’s have failed, the pin was either stuck in or stuck out.

The TRV is I would imagine 20+ years old and the new replacements don’t look like they will fit, I plan to drain the x400 soon and was going to replace the trv’s but a bit stuck now.

Picture attached, appreciate your input

 

[Mottie]

Have you tried lubing the TRV pins and working them in and out?

 

[fattony]

Yes, I managed to move them but they’re not springing back when pressed.

I’m not sure if draining the system has changed pressure has caused them to fail or is it just age.

I can manually push the pin in and out which has some kind of control.

Everything in this house is 20+ years old and on its last legs

 

[Leftum]

That’s an odd look valve. I’d change them all for newer ones. Saves all the hassle

 

[molerat]

Danfoss RAVL valves. You can remove the gland - the nut the pin sticks out of - without draining down, a dribble will come out, then remove the pin, clean it up with a bit of scotchbrite, slap a good splodge of silicone grease around the pin and put back in. I did mine last week, hour and a half to do 9 rads. I would try that first as a crust builds up on the bit of the pin that never comes outside and sticks in the hole plus I doubt you can beat those old heads for sensitivity. You can also buy replacement glands, some available on ebay now part number 013u0070 https://www.ebay.co.uk/itm/116816480122

 

[gas112]

As per molerat but when you take the nut off get a small electricians screwdriver look inside the valve and where the pin sits give it a wiggle as that part of valve sticks on seating

 

[molerat]

The TRV is I would imagine 20+ years old

And the rest. RAVLs were marketed between 1979 and 1986 !

 

[dal5band]

Looks like a complicated job to replace with new TRVs - the fittings on both sides look incompatible with current TRV connections.

 

[molerat]

Looks like a complicated job to replace with new TRVs - the fittings on both sides look incompatible with current TRV connections.

It is. I did one a long time ago, total PITA. You need to remove the female tail from the rad, no mean feat when it has been there for 30+ years and remove the male nut and olive from the pipe which may or may not damage it. 9 times out of 10 the valve is recoverable, they were built to last unlike the cheap rubbish being churned out today. There used to be a full service kit available.