Cannot control UFH temperature

[Phil Giblin]

Electrician has installed bathroom UFH and used Moesgo BHT - 002 thermostat. When I set the temperature ( using both manual and programmable mode ) so say , 22 degrees , the UFH temperature continues to rise beyond this to mid thirties ( and possibly beyond ). He is uncertain why this is happening and says it might be a faulty thermostat. Is he right and is my understanding correct that the UFH temperature control correct in that the maximum UFH temperature displayed should be equivalent to the set temperature ?

 

[Murdoch]

Has the installer set for a floor sensor or room temp?

 

[ProDave]

If the ROOM temperature go to mid thirties, you would know it and be stripped down to your underwear because you were too hot.  Have you actually checked the room temperature with a plain old thermometer?

Is it the case you have asked it to control the room temperature, but the display is set to show the floor temperature which may well be that hot?

The electrician should be able to test if the thermostat is turning off easily.

 

[Phil Giblin]

Thanks for your reply.

The thermostat display panel shows three readings :

1 Room temperature ( this is usually about 18 - 20 degrees and no more ).

2 The SET temperature for the UFH ( I usually set this at about 22 degrees).

3 The UFH temperature. Prior to switching it on , it's about 15 degrees and then increases beyond the set 22 degree to say 35 degrees. The room temperature isn't in the thirties.

The thermostat is in a small boiler room adjacent to the bathroom.

 

[ProDave]

Thanks for your reply.

The thermostat display panel shows three readings :

1 Room temperature ( this is usually about 18 - 20 degrees and no more ).

2 The SET temperature for the UFH ( I usually set this at about 22 degrees).

3 The UFH temperature. Prior to switching it on , it's about 15 degrees and then increases beyond the set 22 degree to say 35 degrees. The room temperature isn't in the thirties.

The thermostat is in a small boiler room adjacent to the bathroom.

My guess would be the SET temperature actually means the room temperature that it is trying to achieve and if the room is not warming up much and not achieving 22 degrees it will remain on.

Test that theory by putting the SET temperature to just 1 degree higher than the room temperature is now, close the door to keep the heat in and come back after a while to see if the room has warmed up by that 1 degree and the UFH has turned off.

 

[Sharpend]

Why is thermostat in the boiler cupboard? Or is it a pipe stat? 

room temp is Actual temp, the Set is what you’d like to achieve and the Ufh will be pipe temp. What are the heat losses in the room? Windows, vents, door open most of the time etc. It may be that the losses are too great for the system to achieve the room Set temp required. ? 

 

[Murdoch]

Has the installer set for a floor sensor or room temp?

???

I would get the installer back 

 

[Phil Giblin]

Thanks for your advice.

13.57 today :

1 Room temperature 21 degrees

2 Set temperature 22 degrees

3 UFH temperature 26 degrees

14.38 today  :

1 RT 21.5

2 ST 22

3 UFHT 31.0

I would expect the RT to increase by more than half a degree in 40 minutes.Maybe I'll need to hang on until it hits 22 to see of the UFH drops.

 

[Sharpend]

Pipes will always be hotter than room temp so that is normal. 
see if when room set temp is reached if the UFH backs off. 

 

[Phil Giblin]

Just to be clear , The UFH is ' Nass Boards Underfloor Heating Mat '

 

[Sharpend]

So it’s not a wet pipe system? 

 

[Phil Giblin]

No. Sorry , I should have made that clear. 

 

[Sharpend]

If you are expecting an electric UFH to heat a room then that will take some time to achieve, what size mat in Watts have you got installed? 

 

[Phil Giblin]

1000 w

 

[Sharpend]

Ok this is not designed to heat a room, merely take edge off of cold tiled floor. 

 

[Phil Giblin]

Am I right in thinking that it is correct for the UFH temperature to exceed the set temperature ? I was given to understand that the thermostat controlled the UFH temperature rather than the room temperature. 

 

[Phil Giblin]

We essentially had it installed as an alternative to a CH radiator. If I have to have it on at 35 degrees then it's going to cost me a fortune. I simply wanted to have it on 22 degrees. 
 

Thanks for your advice , it's very much appreciated.

 

[Murdoch]

3rd try

Did the installer set it to room sensor or underfloor sensor?

We essentially had it installed as an alternative to a CH radiator. If I have to have it on at 35 degrees then it's going to cost me a fortune. I simply wanted to have it on 22 degrees. 
 

Thanks for your advice , it's very much appreciated.

Underfloor heating will never heat a room

 

[Sharpend]

https://support.gw-ec.com/upload/qa/2018/11/19/3019d10504894c7327d18fc07389bbe6.pdf 

this the stat? 

 

[Phil Giblin]

I really don't know - I simply left him to it. Maybe I need to ask him. He's saying it's a faulty thermostat and it needs replacing but is this likely with a brand new thermostat ?