Replacing a fused spur to serve underfloor heating

[DukeGB]

Hi All,

I have one of these:

http://www.greenbrook.co.uk/proddetail.php?prod=T40S-C
and would like to use it to rep...fits on the existing back box. Many thanks

 

[PrenticeBoyofDerry]

What rated circuit would this be fitted to and what is the rating of the accessory/switch/not the protective device the actual current the unit can deal with? i don't think a BS646 is suitable for circuit protection and you should down fuse with a BS1361 prior to the fitting of this unit.

 

[DukeGB]

Thanks for the swift reply. I'm afraid I don't know what the current the unit can deal with is and it isn't obvious from the manufacturer's website. The fused spur I would like to replace was added by someone else to the upstairs lighting circuit - I'll check the RCD but it's probably 5A protecting the whole circuit.

 

[EFLImpudence]

I'm afraid I don't know what the current the unit can deal with is

You were asked what current does the UFH draw.

and it isn't obvious from the manufacturer's website.

Yes, it's a light switch but that was not what was asked.

The fused spur I would like to replace was added by someone else to the upstairs lighting circuit

Are you sure?
That would be silly for an UFH.

I'll check the RCD but it's probably 5A protecting the whole circuit.

Irrelevant and unlikely.
The MCB may be 6A for a lighting circuit.
You should not replace a FCU with a timer. It should be additional.

Programmers and timers for UFH are available; why do you want to use a light switch?

 

[DukeGB]

You were asked what current does the UFH draw.

That was the first half of the question 'what is the rating of the accessory/switch/not the protective device the actual current the unit can deal with?' Is the question I answered.

Yes, it's a light switch but that was not what was asked.

Again, my reply relates to the second part of the question.

Are you sure?
That would be silly for an UFH.

I’m certain – even if it is silly. Tripping the lighting circuit trips the UFH.

Programmers and timers for UFH are available; why do you want to use a light switch?

I already have it so would like to know if I can use it. If there’s an issue with safety then I won’t and will look for a more appropriate bit of kit. There’s an existing thermostat at floor level. I’ll look to see if I can replace this with a combined timer and thermostat in one unit thereby not removing the FCU.

 

[DukeGB]

I had a change of plan for anyone who reads this thread in future. I've replaced the existing thermostat with one that offers all the features I need. No changes to the existing wiring needed.