If it’s not working then obviously there’s something adrift. Whoever fitted it needs to return to double check everything. Once the tiles are over the heated mat it’s not so easy to detect if it’s a break in a wire within the mat which is now under the tiles.

Thanks for your response Daisy but unfortunately the tiles are already on

I know it's a bit too late now, but perhaps it would have been wiser to test it was working before the tiles went down? I know our electrician tested ours before our flooring went down.

The electrician said that if the thermostat is working he did everything right and it’s not his fault
The tiler said it was not the first time when he put tiles over UFH and it’s not hos fault and I will have to cook in an unheated kitchen
What a pain

I think perhaps the electrician should have been involved in some way when the mat first went down.

Can the electrician do a resistance test to check to see if there is a problem with the mat itself? This would at least establish where the issue is. It could be that the mat was damaged during the tiling process. This should have been done before the mat was laid, once it was laid prior to the tiling and monitored during the tiling.

I'm surprised that he hasn't already done this test, to prove he isn't at fault - instead of giving you an airy fairy response.

I think that was another cowboy work. He did nothing from what you said and now he is washing his hand.
Anyway, Thanks for your replay

I too think it should have been tested before the tiles went on. We have underfloor electric heating in both of our bathrooms. Hubby fitted it (he’s in the construction industry so not new to such things) and I remember him saying I’ll test it before I put the tiles on. It’s been down for many many years.

We have both spent too much time sitting on the loo because the wires are closer together there and the floor is lovely and warm (ours was not on a mat).

Really, you need to get him to return. You’ve had a job done which is inferior. Have you paid him dare I ask?