Process for turning on electric heated floor under Porcelain tiles

happyhero

Hi I have fitted some Warmup heated floor loose lay cable/DPM system and positioned it as per the manufacturer’s instructions to have the potential to achieve the maximum heating effect of 230W/m2.

I fitted 10mm insulation/backer boards and then the special red sheet with castellation’s mat for the cable. I applied adhesive directly to mat and cables and fitted large (600 x900mm) porcelain tiles. Finally I grouted the tiles.

So I’ve been warned about heating the floor gradually or risk cracking tiles, so how long before I turn on?

Also how do I build the temperature up i.e. at what rate, per day, per hour etc., starting at what temperature to eventually get to maximum, can anybody suggest a sensible or known preferred pattern to insure no problems.

Plus once this is completed can I assume it’s always okay to turn it to maximum at any time from being off or is it wiser to stay away from maximum for a long period?

I appreciate any advice you can give me.

rob7475

If you've used a decent flexible adhesive, you shouldn't have any issues with it cracking because of the heat as long as you don't whack it up to full blast within a couple of days of tiling.

Have you installed a thermostat / timer as part of the underfloor heating system? It should have come with a temperature probe which is under the flooring. I'd power up the thermostat/timer and see what temperature the probe is picking up. Initially, I'd set the temperature a degree or two above that for a day or two. You should feel the tiles heat up a bit. After a couple of days, if the tiles aren't warm enough, turn it up a bit more until the floor is a temperature you are happy with.

Hopefully you're not planning on heating the room with the heat mat - they are mainly for taking the chill off the tiles. As a heat source, they are not efficient  and not very effective unless you have them going at full power 24/7 which will reduce their lifespan.

I fitted one under our bathroom floor around 8 years ago. I have it turned on 24/7 but the thermostat is set to just take the chill off the tiles which along with a central heating powered towel rail, works well.