Dispute - underfloor heating doesn't work properly

charli_lennon

Hi all,

We have recently had our kitchen fitted and we decided to go for underfloor heating. It gets warm as you would expect in some places and not in others.

We have had it checked and the heat mat is working as expected. So the answer was either the tiles or the insulation.

The tiles are man-made and as it works in some areas we are pretty sure it's down to the insulation.

The fitters claim they have used the appropriate primer. However they didn't use the heat insulating primer supplied by the underfloor heating mats manufacturer.

Any advice gratefully received.

andyhop

Type of floor??

Insulating primer is a new one to me. Suspended floors should be packed with insulation to minimise heat loss. How warm are you expecting? Most max out around 28-32 degrees. You need a infared heat gun to accuratly measure

charli_lennon

It's onto concrete floor and it's a ceramic tile on top. The tiles are warm in places and cold in others.

andyhop

Is there any insulation in the slab??? If not you will find it may never get to its temperature set point as its heating a massive slab of concrete

It may need inspecting with a thermal camera to see if the mat actually runs the full area, might have large chunks missing from a mat thats too small!

charli_lennon

I don't believe so. I saw them lay the mat and where it runs there are points that are warm and points that aren't.

For example on one side of the kitchen we have two tiles that get warm and then 3 in between that don't, all on the same mat run.

andyhop

Insulation, insulation, insulation!!!!!

Any cold spots, draughts, dense concrete slabs is a receipt for disaster . Unfortunately nothing that can be done

Did you fit 150w per sqm mat designed for solid floors or did you use 100w designed for timber??

charli_lennon

Is it the fitters problem or ours? It states in the installation guide to use insulation. We only saw this today. They sourced the mats and fitted them.

If we had known we needed insulation we'd have happily paid for it. We basically can't use our heating and it's cost us about a grand.

Although we haven't paid the fitters their final installment and personally I think they have to take responsibility for this. Am I being harsh?

andyhop

Very harsh

To make electric underfloor heating work on a concrete slab needs at least 50mm of kingspan k18 or similar, ideally 100mm plus. We got caught out a few years ago and now its insulated to the max

Would you have allowed your kitchen floor to be dug up? We get customers who expect to flick the switch and have instant heat!!! Minimum 8mm screed, plus 5mm adhesive bed plus 12mm tile before it hits your foot!!

charli_lennon

Yes but we know nothing about this, if we have of been told that concrete needs something doing to it we would have either done that or not had it installed.

System

How old is the house? And who advised on the spec of the heating?
Definitely sounds like the problem is insulation, if the fitters specified and installed the system they should be responsible for making sure the floor was suitably prepared, which includes insulation...

andyhop

A £1000 job could have easily turned into 3k job if the floor was broken up and insulated.

Would you expect a tiler to do this??? What did the installers quote state?? Did other installers quoting not mention insulation??