What is this and why would it stop UFH warming up?

[lavinpj1]

In the below pic, what is the part boxed in red? It sits at the top of the pump in the UFH system. It's wired into the wiring centre with 2 (white) wires between the switched live from the thermostat and the live feed to the pump and 2 port valve.

The system works fine for a short while and then this element stops allowing current to flow to the pump and valve and thus the system shuts off. It comes back on again every 10 minutes or so but only for 30-60 seconds before shutting off again.

Untitled

• lavinpj1
• 29 Dec 2014
• 1

 

[Tipper]

My UFH has an overheat thermostat wired back to the control box. It stops excessively high temperature water being pumped around the floors which could damage the floor coverings. Sounds like that's what it is.

Is there any adjustment on it perhaps under the cap? Or maybe the link it out so the UFH runs longer.

 

[lavinpj1]

I thought it might be that. I'll take the cap off and have a look.

The boiler is set on max and seems to heat the water to about 93c so this may be triggering it.

Is it reasonable to just bypass it?

 

[muggles]

The boiler is set on max and seems to heat the water to about 93c
Is it reasonable to just bypass it?

Wow that's far too high for any practical purpose, and is also very inefficient (IE, it's using a lot of gas). Turn it down, might solve all your problems. Do not bypass the stat, it'll ruin your floor and at that temperature could also cause the pipes in the floor to burst

 

[lavinpj1]

Thanks - what's considered a reasonable temperature?

 

[muggles]

For efficiency you should have it as low as you can get away with whilst still being warm. Try 70°C and see how you get on with that

 

[lavinpj1]

Will do - thanks.

 

[Diyisfun]

My ufh has a stat & a temo gauge.
From my instructions...(the word max is bold & red)
Once the temperature gauge gets to the temp set by the head or electronic sensing element the head will start to shut and stop taking water from the boiler. Note the electronic sensing element is set at 45°C and can be adjusted upto a MAX of 65°C

 

[lavinpj1]

Interesting - thanks for the info. I'll take the cap off and see what the deal is with it.

My boiler is set at maximum because each room has a TRV and this is what the guidelines I found suggested. I'll tweak the stat and turn the boiler down to see if I can get some heat under the floor.

 

[Diyisfun]

My boiler is set for the rads in the rest of the house,(don't know what temp). but the ufh heating is controlled by a programmer, which controls the diverter valve & t/stat that is before the manifold is controlling the temp of the water going to the ufh.
The uhf heating pumps water round its circuit as the water loses temperature then it is mixed with water from the boiler.

 

[lavinpj1]

Seemed to do the trick, thanks

 

[Norcon]

If the stat has kicked in then the blender has probably developed a fault.
Above 60c into ufh and you will damage the screed and certain floor coverings.
If you like getting your feet cooked though that's your choice.