wiring requirements for electric underfloor heating

[james beckford]

evening gents,

bit of a sticky one that i would like some help on tonight,

called in by tiler fitting underfloor electric heating and asked to quote to provide power supply as far as the thermostat units.

The spec is as follows, two areas to be covered with seperate thermostat/control unit, 1st area 21m2 2nd area 18m2, total demand 200W per metre square, total maximum load 33A

Initially thought of spuring off ring but same ring in both areas on 32A breaker therefore no go,

only 1 spare way in CU available

both thermostats to be mounted adjacent to each other at border line between two heating areas.

no problem running 10mm t+e to where the controls are to be located but having a complete brain fart about how to split down to controllers and provide the necessary protection at that point? obviously SFU only good for upto 13A and one circuit is 19A

 

[Octopus]

Are you sure that your calcs are correct?

 

[SirKit Breaker]

Have a read of the installation instructions. I have never installed a domestic U/F heating system that needs anything bigger than a 13a SFCU.

Cheers...........Howard

 

[Octopus]

Have a read of the installation instructions. I have never installed a domestic U/F heating system that needs anything bigger than a 13a SFCU.

Cheers...........Howard

I've seem one on a contactor, big room!

 

[Richard Burns]

Use 100 or 150 W /m2 matting instead or split each room down to two areas and use individual controllers for each area or install a contactor for each room that is operated their own controller. I think some need something extra if using contactors.
I would not like to see the electric bill for that!
and I hope they have a suitable supply to take the extra load.

 

[james beckford]

Are you sure that your calcs are correct?

Unfortunately tiler hasnt purchased system yet has just quoted wattage figures from suppliers of 200W per metre square,

Yes the rooms are quite large 21m\2 and 18m\2 he is using 200w matting because of the size of the area that cant have UFH because of furniture etc.

May have to persuade him to split into 4 areas as this is the easiest

 

[Octopus]

Just make sure that if he fits the UFH you test it before and after the tiles go down!

 

[james beckford]

Just make sure that if he fits the UFH you test it before and after the tiles go down!

If i was signing of the job i would ensure full testing, however I am just providing the power supply, allegedly the supplier has an installation team it just seems that they cant cope with anything bigger than a bathroom thats only pulling a couple of As