Electric underfloor heating install

[Keefa]

I am thinking of installing electric underfloor heating (tile warming only) in my bathroom and was wondering whether there was any way that I could use the light switch to turn on the floor heating as well. Before you all jump on me, I understand that the heating will require a dedicated and high rated connection at the CU but is there any way to use the light as a trigger (in a similar way as the extractor fans operate) rather than needing an additional switch or leaving the heating on all the time?

 

[andemz]

well if it is in the bathroom it will need to be rcd protected firstly. I have just done this in my house and this is the setup as follows.

I spured from an RCD double socket into a non switched fused connection unit. Mine was 3 amp, but you would need to work it out for your own setup. From the FCU i ran a 2.5mm2 T&E up to the thermostat for the L,N,E supply. In the thermostat i have a load L,N,E Supply and a sensor. The thermostat is positioned on the outside of the bathroom wall runs down the outside of the wall and then an hole through right at the bottom is heat resistant tubing that was supplied.

This seems an adequate system. I can turn it on and off whenever i want, set it to come on periodically and can keep it on all day night and forever.

As for dedicated and high rated connection at the CU i don't understand that as it can come from a ring circuit by means of a spur into FCU.

Although i am no electrician. I think that the power that is required for the underfloor heating will not be able to come from a lighting circuit as demand will be too much. Also how would you regulate the temperature from the light switch and how would you connect the sensor to the switch?

 

[brown-nought]

Have you considered a contactor? (They are DIN rail mountable relays.)

Dedicated heater circuit through a contactor. The control side could be supplied off the light circuit via a 3a FCU. (that way you can isolate both the load and control sides).

You could also consider supplying the control side via a time switch with a DP pull switch (1 lights other control) override. This way the tiles would heat before you venture out of bed.

Have a think, or call a pro and let us know how it goes.

 

[Keefa]

Thanks Brown. That was the type of setup I was thinking of. I'll give it some thought and see how we go.

Anyone know if this would be legal? What kind of regs are there for this type of thing?

 

[crystal ball]

Using a contactor is ok but uf heating takes a while to warm up, by the time you had showered etc it would hardly be noticeable, timer is the best way

 

[andemz]

I wholeheartidly agree. That is unless you want to keep the light on. having it thermostaticaly controlled is far better and more versitile, and you wouldn't need to ask the question of legality