Problems with Underfloor Heating Cable - TilersForums.com

[Mark02]

I am having a problem with my underfloor heating cable in my bathroom. The cable was installed at about 5cm apart on top of a 6mm tile backer board. About 8-10 mill of SLC was then poured over the top before a 10mm slate tile floor was fitted over the top.

According to the thermastatic floor sensor it takes about 3 hours to reach about 25 degrees and 5 hours to reach 26 degrees. However when you touch the tiles they they do not feel hot. But as if the chill has been taken off them?.

Am I hoping for a bit much. Was at B&Q and felt there under floor heating set up. The tile was about 100 times warmer than I am achieving.

The bathroom is small at about 3 sqm. I have a 400 watt cable. This is wired to a breaker which then connects to a plug socket off the ring main.

Is this all normal?. I was thinking of pulling it all up fitting 30mm of tile backer board and a 500watt cable matt.

any help would be greatly appreciated

Mark

 

[Mike]

it doesnt sound like it's working properly, it sounds a bit extreme to rip it all up though. did an electrician fit it? is it new and has it worked before? have you tested the probe?

 

[Mark02]

Yes was all fitted by an electritian and part p tested etc . Its our second bathroom so we havent been using it that much until quite recently and hadnt used the underfloor heating until this winter. I have tested the resistance of the heating cable and thats fine. Havent tested the probe, the manual states that you would get an error message on the thermostat if there was a problem with this?

I dont want to rip it up, but hate things that dont work as there supposed to. Keep thinking that there is not enough insulation and the heat is just going downwards?

 

[Dan]

How long have you been running it for? Is this pretty much the first time you've turned it on?

I would guess that the 6mm insulation board would be fine to be honest. How big is the area, and how big was the mat? And what wattage per square meter is the cable that you chose?

 

[Mark02]

It was installed in July 2011 and first started to use the UFH in November 2011. The total floor area is about 2.6 sq m. Have a 40m cable length only had to take out toilet so covers 95% of the floor. The cable is 400 watts.

 

[Ian]

Is it an insulation board you have used or a cement board, under the wire?

 

[Mark02]

Its Cement Board

 

[Ian]

Its Cement Board

That may be part of your problem, cement board isn't as good for insulating as other products such as marmox, so a lot of your heat will be going down the way instead of into your tiles.

 

[DHTiling]

How long are you running it before testing tile temperature?

 

[Mark02]

its a cement based tile backer board and has same spec as marmox