Underfloor Heating over 13A??

[madger]

Hi there, I’m looking for some advice regarding underfloor heating. The conservatory is 20.9m2 and total power is 3.344kw. At 230v this gives me a current rating of 14.54A. The controller is rated at 16A, normally I supply controller via 13A switched fused spur but with this increased loading I believe I can supply via a relay? Could anyone please advise what type of relay I would require? and if possible where it can be purchased. It would need to fit locally into a dry lining box. Many thanks in advance.

 

[Deleted member 9648]

A contactor would be preferred,with a 16/20a feed to the contacts as a radial from the CU via a 20a isolator, and your controller feeding the coil. There are likely to be several elements on such a load and these could be split over the 3 poles of the contactor.
There is no way you will fit a contactor..(or relay)...in a dry lining box.

 

[Guest123]

:iagree:

 

[madger]

The trouble with the contactor option is that it has to be mounted locally, thus every time the heating goes on/off you get a great 'clunk' I'm sure i saw a power relay on a system a couple of years back mounted in a double 48mm dry liner?

Should also have added that dedicated supply was no go due to construction of house/position of fuse board so local ring utilised.

 

[Guest123]

I'm sure i saw a power relay on a system a couple of years back mounted in a double 48mm dry liner?

Best get googling then.

 

[RogertheBodger]

Can you clamp the circuit to see what it is actually pulling, it may well be taking a little bit less than you have calculated, especially if your voltage is higher than 230. You may find the current a little less than 13A. worth a look before you start trying to fit a contactor in.

 

[madger]

Will try that Roger, wanted to cover my bases so have done little research and found 16a in-line fuse holder which I can use in conjunction with 20A dp switch instead of 13a fused spur if load is greater than 13a as controller rated at 16a. With regards to the power relay (for future reference with increased loads) I would still appreciate any help available.

 

[sedgy34]

The trouble with the contactor option is that it has to be mounted locally, thus every time the heating goes on/off you get a great 'clunk' I'm sure i saw a power relay on a system a couple of years back mounted in a double 48mm dry liner?

Should also have added that dedicated supply was no go due to construction of house/position of fuse board so local ring utilised.

When you find one let us know, I've had to do the same in the past and it looks crap in a conservatory and the clunk noise int very good either

 

[Guitarist]

Sorry if I'm misunderstanding. You say that you can't run another supply in? If so, a contactor is no use anyway, as you will still need a larger supply taking to it.

 

[madger]

Sorry to confuse, my controller is rated at 16A so no problem. A Contactor could be used to switch load up to say 20A on a 32A mcb as the controller is only rated at 16A so in this type of situation the controller would operate the contactor. It was in this sort of scenario that I was wondering if an alternative to a contactor was available.

 

[sedgy34]

have you had to spur off ring circuit to 20 DP switch if there is no seperate supply??

 

[madger]

That's what i plan to do if it pulls more than 13A, won't know for sure untill put clamp meter on when i connect up. Also need to check with manufacturer before fitting mat as calculations done using 160wm2 mats when i may be able to get away with 130wm2 as Amtico flooring being fitted over Ecomax duo top boards.

 

[sedgy34]

if you have sockets on same fused spur dont bother with the clamp meter it will need its own spured supply
ive had to do the same in the past

 

[Guitarist]

I think this is one of those cases of prior planning...
Was the floor installed without consulting you, or is it not down yet? If it was installed without adequate supply being available then that is poor design.

 

[Dave 85]

Please forgive me if i'm being stupid guys, but if its 14.5 amps, and the controller is rated for 16amps, why cant he just have a 16amp radial circuit, through a local double pole 20amp isolator ?