Underfloor Heating

[eskimo39]

Hi a friend has had a sparky in to do the first fix for his kitchen and conservatory. However after numerous phone calls the guy will not come back to finish off the work.

I went around today to see if I can help and am a little bit puzzled.

There is going to be 2 underfloor heating systems

1. Kitchen
2. Conservatory

The original sparky has chopped in 2 x 1G 25mm boxes at socket height which have been spured off existing sockets with 2.5mm, I would assume are for fused spurs, however after speaking to my friend he explained that the original sparky told him he didn't need spurs and was going to just put the thermostats on these.

I on the other hand would imaging you need a fuse spur (as the mat is run from flex and would surely require protection) and would also require having a thermostat chopped in at a much more suitable height for programming etc.
The thermostat comes with a temperature probe which I know needs to be installed under the floor tiles but I have never seen a stat situated so low down and have never seen UFH without a fused spur.

Am I wrong?

 

[dazza69]

No eskimo39 your bang on! The thermostat is usually located about 1.5 meters from finished floor level and is supplied from a switched fused spur which is a means of isolation and fusing the matting down to usually 3A but this does all depend on the size and rating of the matting. The under floor probe also runs up to the thermostat and i usually install it in a 10mm flexi conduit so if it ever fails it can be easily withdrawn and replaced without having to dig the floor up!

 

[Scott F]

Similar situation last year fuse and stat at socket height in new builds flats for my ex boss. .The underfloor heating may have been an after thought and the stats put at that height because they were next to a socket.Or maybe the underfloor heating garb stipulates those heights .I think it was "Senates "own.Just a thought .Technical helplines can be pretty useful and usually point you in the right direction.

 

[dazza69]

Stats at socket height are usually because customer or installer doesn't want the wall chopping out! if its on a stud wall you can usually get all cables to that height with out any damage to plaster work.

 

[johnnyb]

dazza. Although its great for maintenance purposes as you have said, if the probe is in a tube won,t that give a false reading to the stat, if not i think i will start putting them in a tube, it seems a good idea.

 

[amberleaf]

remember
the heating mat and floor probe should be tested prior to screeding
ps,753.514 identification & notices : notices must be fixed to distribution board
notices ; look at fig 753 - 226

 

[dazza69]

HI johnnyb, no it shouldn't give false readings. One of the manufactures i use even supply you with the conduit! Just remember to put a couple of pieces of leccy tape over the end to stop any screed or adhesive getting in.

 

[eskimo39]

Just done some research today. The probe will actually work better in conduit so long as it is sealed to avoid screed/adhesive getting in. If the probe is in it's own air it records a much more accurate temperature.