Electric underfloor heating, forgot the floor sensor

[compact]

We have had Cozytoes heating matt laid and tiling done.
They have come to install the Touchscreen Timerstat and they have realised they forgot the Probe/sensor that lays under the tiles amongst the matt.

I know, cowboys, plonkers, not paying for it etc etc. However is it possible to fix this rather than taking everything up.

I was thinking, as the matt starts at the door, we can gently take up the 1st tile, scrape out the adhesive etc to expose the matt and lay the sensor between the wires.

Do you think this is possible? If we are careful?

 

[dilalio]

Sensor should be 500mm into the room.
Yes, if careful you can take up a tile or two, but which way do the heating loops run? For, or against you?

 

[compact]

The room starts off as a corridor that is 800mm wide.
The tiles are designed like planks of wood, so thinking i can run the wire down the wall and then in from the side, lining up with the zig zag pattern so as not to cross a wire.
However as the adhesive is set hard I am concerned of damaging the matting. Can i set the sensor just under the tile, or should sit as close to the matt as possible

 

[dilalio]

How thick is the adhesive? Usually, the end of the stat probe is like a bullet which has to be notched into the floor slightly so as to sit flush with the top of the heating cable. If you have a really thick bed of adhesive then you might be able to do it.
Also, most heating matt systems advise putting the sensor wire into a mini conduit so that it can be replaced in the event of failure.

 

[fezster]

I had a heating mat repaired once, because the numpty bathroom fitters didn't bury the entire heating element in adhesive. The first couple of cm were exposed to air, and burned out after about 6 months.

Anyway, I used a guy who does contract work for warmup and he cut the grout around the tile in question out, then carefully (but skillfully and quickly) smashed and removed the broken tile/adhesive, leaving just the bare wire. Repaired the wire and left reinstatement to me. So it can be done. I guess he had the advantage of knowing he could repair the wire should he have damaged it further.

 

[compact]

Hi @fezster thanks for the reply.
I spoke to Cozytoes this morning.
It apparently happens more often than you think.
He said use a ball hammer to gently smash the tile. So hopefully that can be done easily.

@dilalio The sensor is quite small, a couple of mm across, so hopefully fits in the adhesive.
Thanks for the conduit tip, a good idea, will have to see if I have enough height in the adhesive and can find something to use for the conduit.
Can only think of a drinking straw being small enough

 

[Ian H]

I recently replaced a broken floor tile over underfloor heating. Wasn't too bad, I used a tiny chisel to crack out the old adhesive and the new tile went in nice and easy.