TRVs no longer stopping flow [PHOTOS]

[BeefSteakTomato]

This is my first post, I'd really appreciate if you guys in the know could take a look...

I've noticed all of a sudden my TRVs are no longer stopping flow. When the valves are closed tight they are letting hot water through. Some radiators when the valve are closed get lukewarm, while others are very hot.

This happen all of sudden to all of the TRVs in the house and coincided with the cold weather. (Greater temperature differential, so more pressure to overcome the valves?)

What should I be looking for and what is the cause?

Context
1900's semi detached. 8mm dia pipe. Combi-boiler as photographed. Radiators as photographed.
Photo's might be completely pointless, but rather give you more to go at than too little.

PHOTOS
https://www.dropbox.com/sh/9umt279f8meqcbx/AAABqbqTkidJC7LWz21hwOZja?dl=0

 

[JohnD]

When you say "all of a sudden" do you really mean that all the valves worked correctly on Friday and all went wrong on Monday? Or do you mean that you only just noticed it when the weather got cold?

How long ago do you know for a fact they all worked correctly? What has happened to the heating system since then?

Can you see a brand name on them?

 

[D_Hailsham]

Has each TRV been on the winter setting all through the summer? If so, the pins are probably stuck. Remove the TRV head and make sure you can press the pin down and it jumps up when released. If that doesn't work, tap the side of the valve body fairly hard with a hammer to release any stuck valves.

 

[BeefSteakTomato]

Thanks guys, the values pins were stuck.

 

[D_Hailsham]

When the summer comes, set all TRVs to Max, the problem will then not occur next winter. But don't forget to reset them to the desired setting.

 

[gas112]

And why wont it happen next year D hailsham ?

 

[D_Hailsham]

And why wont it happen next year D hailsham ?

Because the TRV will continue to operate trying to maintain the set temperature.

If you leave the TRV at a low setting (20C) and it is continually warmer than that the TRV will stay permanently closed. But if you set the TRV to Max (28-30C) it will stay open if the temperature is below the setting and close when higher.

Setting to Max may be a bit optimistic as UK temperature rarely get that high.

 

[gas112]

But temps do hit that high in uk so your idea is flawed so only way would be to remove head

 

[D_Hailsham]

But temps do hit that high in uk so your idea is flawed so only way would be to remove head

Overnight?

 

[gas112]

and you know exactly how long it takes for a trv to stick ? is it minutes hours days weeks , i have freed them and they have stuck again minutes later

 

[D_Hailsham]

Sludge in the system? Cheap TRVs? Worn out (unlikely)?

I have got Honeywell VT200, which are over 10 years old, and they have never stuck, even though I leave them on the same setting all year round (Don't do as I do etc.). On the odd occasion I have removed a head to check the pin it has operated perfectly. The same went for the TRV4's which were over 10 years old when I left my last house.

 

[gas112]

Thats ok you must be the pro and have dealt with 20 trvs in your life .
I freed 35 in one premises the other week all ha been left on high.
Why wouldnt a trv seal wear out
Ah trv 4 which we promise wont stick like the trv3 which we promise wont stick like the 2 model which was promised wont stick like the 1 model , I think after 4 attempts they just thought fek it they will all stick at some point

 

[nauseous]

This thread should be a 'Sticky'