Underfloor Heating (WarmUp) has just stopped working

sillygoose

You don't have to have any sensor, lower wattage UHF it can just be turned on /off on the basis of the timer function.

But IMHO to be fitted properly it should have both floor and air as they serve different purposes. UHF controllers can deal with both together. The floor sensor is used to measure and limit the temperature the floor is allowed to reach and protects the heat cable from damage/shortened life by getting too hot.

The room sensor cuts wasted energy, if the room is hot (and the tiles should be on a layer of insulation) then they will be room temperature and won't feel particularly cold anyway so the room sensor can switch the floor off.

If the UFH is only a low wattage 'comfort' heater then a room sensor may not be necessary. I would always use a floor sensor though.

Perhaps some of the error messages on your controller are to do with incorrect mode being set? most controllers have an inbuilt memory or backup battery to keep the settings. If it was powered down too long it may have gone back to default (unsuitable?) settings - or perhaps the tilers fiddled with it because they were being baked in there. If the controller is set to say just use a room sensor as thats all there is, then gets set to a mode to for example expect a floor sensor it will detect the 'missing' sensor as being faulty and may refuse to operate.

As to your leak pretty much impossible to say via the internet. I wonder, as it happens after a period of time if its a messed up overflow outlet pipe somewhere or one that has been left not going anywhere. A toilet cistern for example with a slightly leaking fill valve will gradually fill until water reached the overflow level and then start siphoning down there at quite a rate. During the day occasional flushing of the loo would reset the cistern to the normal level - perhaps just often enough before it gradually reached overflow level again.

melb

yes someone at work said they'd had that happen to them and we're going to mention this to the plumber when he comes. We can't see where out overflow valve for the toilet is. The bathroom is an awkward shape it's long and narrow with the corner bath sort of wedged into the far end of the room under the window and then the toilet projecting from LHS wall and then sink on same wall. All outlets, drains etc go out underneath the floor tiles or behind the bath so nothing is visible without removing the bath panel. the error code on the UFH said external failure and the red light was flashing. however we reset it to factory settings and thought hey presto and tried to go through the resetting process although some of the questions were a bit specialist. anyway the light started flashing again so we rang the Warmup helpline who apparently were very impatient and just said obviously the tiler has cut through the wire. Will try and reread you advise re what to do with the stat and try again. I really appreciate your help but the more online reading i'm doing the more i think this could run and run! (pardon the pun!) Could water be leaking from the shower unit behind the tiles?