UFH pump stopped working. Replaced and still not working...possible sensor issue?

[FateFirst]

Apologies for any terminology used that doesn't make sense to any plumbers here - not sure on part names etc. so please correct me as I'm always keen to learn and understand

Moved into a property about 3 years ago and water UFH already installed (JG Speedfit One Room).

Been working fine and then stopped shortly before Christmas 2019.

Power, hot water valve and thermostat appear to be working. Had a work colleagues brother come round to help (a couple of years into plumbing). He replaced the pump for a new one (as assumed dead) and it still didn't power on the pump when everything was on and thermostat cranked up.

Plumber checked power and all was fine down until you get to the little white box (see image with red circle) which appears to connect to the hot water feed. Plumber bypassed this to check and when bypassed the pump came on and started working. He has left this bypassed for now but stressed that it can't be left like that as there wouldn't be any control now. So in order to stop the pump I need to power off the UFH completely (which is a simple wall switch).

As this is part of a kit do I need to replace the entire kit or can you buy that specific part to replace? Is it even something you can replace?

I really appreciate any advice/tips - just trying to manage my expectations and cost.

Thanks all.

 

[SJB060685]

Overheat temperature sensor installed and failed?

Edit: read whole post. Yes hes linked it out for now which isn't a permanent fix. You should be able to get the offending part but others will be able to tell you more.

 

[Brambles]

SJB is correct. Two points, be wary of running a wet underfloor heating system ( if it is gas or oil fuelled) without temperature control. You can ruin expensive floor coverings in a few hours if you get flow temperatures of 70 degrees plus.

Establish why the overheat stat has tripped - it is just as likely to be the blending valve and not a faulty sensor.

In my business anyone who wires out a safety / control device (for other than testing) and leaves the customers premises is asked to leave.

 

[FateFirst]

Thanks for both of your inputs - really appreciate it.

Plumber wasn't going to leave the bypass in place but I asked him for now while we have no heating downstairs in that particular room. It is a large thick-tiled open plan living/dining area which does get pretty cold (according to the wife - while I don't mind it).

I'll probably look to get someone out to see if they can isolate the issue and replace it. I was more just checking here if it is something that can be replaced really or would it require a more hefty kit swap-out etc... I guess the more information I can provide to the new plumber coming round the better

Thanks again all

 

[SJB060685]

I didn't go into great detail because I was rushed off my feet but Brambles advise is correct. Linking out the limit stat should only be used to diagnose and confirm a fault. If you're using a gas or oil boiler with higher flow temperatures than a heat pump then you risk damaging any screed and flooring. It could be a faulty stat or the blending valve, if it's the latter and you've linked it out then you will most likely cause damage, so although you don't want to hear it it's the right thing to do to not use. I would get your guy back and ask him to confirm the fault and see if they can source a replacement.

 

[Brambles]

Worth asking the guy for the old pump back - it was the most expensive bit of kit on the manifold and probably nothing wrong with it.