UFH mixer valve pin replacement

[Bof44]

Your help please…

We have wet underfloor heating in our kitchen and it hasn’t worked since moving in a year ago. I have now decided to try and fix it as the floor is painfully cold.

The Grundfoss pump appears to be running and the actuator pin moves freely.

However on removing the thermostat head (bottom of photo) the pin is completely stuck in with nothing there to grip with pliers.

Assuming this is likely to be the cause of the problem and that a replacement is required. Can anyone identify the valve make/model as I can’t find this anywhere?

I believe a complete heating system drain will be required to remove the valve, otherwise I would take it off to try and loosen?

Thank you very much!

 

[oilhead]

Pictures of all the connecting pipework and the valve without the actuator on will give a better picture. Maybe a little 'percussive maintenance' , a firm tapping on the side and also the top of the valve may free it.

 

[Bof44]

Thank you for your reply - I have previously tried some slightly over gentle tapping without success.

Some more photos attached.

 

[Madrab]

That's a contact temp sensing head - not a TRV (thermostatic radiator valve) though they do work in the same way. The vial sits inside the pocket at the top of the pump to maintain set flow temps. Obviously the valve itself is damaged and needs replaced.

Yes the system will need isolated and that valve removed and a replacement installed. Use the red valves to isolate from the loop, if there any valves on the inlet and return to/from the CH? You could use the Nu Heat valve and use a decorators cap to lock that valve down.

 

[Bof44]

Thank you @Madrab!

Will I need to replace the head too? And when you say replace the valve, is that just the insert at the bottom or the whole brass block? Either way knowing what part to order is my challenge.

Unfortunately, there don’t seem to be any other isolation valves so your tip on using a decorators cap is great. I presume that will also mean closing the silver ball valve in the right hand of the photo.

Thank you again!

 

[Madrab]

That silver ISO looks like it's on a Tee up to the other pipe? Not sure from the photo so unsure what it may isolate or if it's some kind of bypass if it's connects into the pipe above. Not sure about the remote sensing head either, all depends on whether it works or not really and if the replacement valve will be compatible.

I would take a guess that the valve in the bottom of the brass block may be a normal UFH valve but you wouldn't know until it's out. That setup isn't familiar so not sure exactly what components it uses. Once the valve is out though, you may actually be able to free it up but if not then a replacement would have to be sourced.

A pic of the valve when it's out and sent off to a reputable UFH supplier then they may be able to identify it for you and offer a replacement.

 

[Bof44]

Thank you again. Really appreciate you taking the time to help.

 

[MrUFH]

hi, did you manage to get this replaced? I curious to see whether it's the mixing valve that is stuck.

 

[Bof44]

Hello @MrUFH

I have the part on order thanks to some excellent support from Nu-Heat.

For anyone else the part number for the pin valve insert is DZSW24-C available on their website.

Once it arrives I then need to figure out if I can replace without having to drain down the whole system.

I’ll let you know if it fixes the issue.