electric underfloor heating won't work

[jkrikler]

we have installed underfloor heating below a ceramic tiled kitchen floor.

the heating worked for about two hours and then tripped the RCD on the distribution board. after that the heating wouldn't come back on and the board kept tripping. our electrician said something about a possible earthing problem but couldn't solve the problem...

the thermostat/controller is now disabled and i fear the problem is with the wiring below the floor and cannot get at it.

is it possible it's the controller or if not is there a way to salvage this?!

thanks
jim

 

[Softus]

our electrician said something about a possible earthing problem but couldn't solve the problem...

Get yourself a competent electrician instead.

is it possible it's the controller or if not is there a way to salvage this?!

Get your new electrician to carry out an insulation resistance test on the element tails.

 

[jkrikler]

thanks for advice softus - you may be right... though he has been decent generally(!)

what will testing the tails tell us and what would the options be?

 

[Softus]

you may be right.

May be?

what will testing the tails tell us

It will tell you the resistance of the insulation, of course.

and what would the options be?

Er, what?

If you mean What should I do if the mat is faulty?, then the answer is that you can either replace it or leave it there.

 

[jkrikler]

thanks for your clarity!

yes i'm pretty much resigned to this being a dead loss. to be honest i don't know what our electrician did by way of tests before he disconnected the controller. it is a good idea to have someone else look at so will do that...

a friend mentioned that if the heating wire is faulty it may be possible to trace the point below the floor and then remove the relevant tile to get to it (probably dreaming i know!) - do you know anything about that idea (keep it clean...)

 

[Softus]

a friend mentioned that if the heating wire is faulty it may be possible to trace the point below the floor and then remove the relevant tile to get to it (probably dreaming i know!) - do you know anything about that idea

Not really. Equipment does exist that can determine the distance along a wire to a broken conductor, but I wouldn't have confidence that all other parts of the mat have a long life in front of them.

(keep it clean...)

Good idea; I've just cleaned it.

 

[ban-all-sheds]

we have installed underfloor heating below a ceramic tiled kitchen floor.

Who installed it, and when?

 

[jkrikler]

hi b-a-s

it's a wickes product installed by the builders / tiler and connected by the electrician. if you're thinking whether we could get them to sort it or if there's a warranty the answer effectively is no.

i think it probably got damaged during the tiling - the guys we used were not likely to have been very careful we discovered...

the frustrating thing is it did actually work at first and now we don't want to rip up the floor to get at it! that's why i wonder if it's worth double checking the controller or if there's some way of finding the fault on the wire?

 

[ban-all-sheds]

it's a wickes product installed by the builders / tiler and connected by the electrician. if you're thinking whether we could get them to sort it or if there's a warranty the answer effectively is no.

There doesn't need to be a formal warranty - when you have services carried out you have rights under the Supply of Goods & Services Act 1982.

Work is required to be done with reasonable care & skill and goods & materials supplied as part of the service should be of a satisfactory quality i.e. free from defects.

Get them back in to sort it.

 

[nozspark]

What you need to do is get an electrician in who will (at least):-

a) Test the insulation resistance of the mat element to it's earthed shield
b) Test the continuity of the heating element
c) Test the continuity of the sensor probe

They might also want to check the supply to the controller

If you do have a fault then there is no way you can repair the heating element. You will either have to leave it or rip the tiles up and replace it.

The most likely causes of a fault in the element are

a) Manufacturing fault (the tests mentioned above should have been carried out before laying the tiles!!) VERY UNLIKELY
b) Someones crushed the heating element beofre it was tiled
c) When fitting the white goods and anything else to the floor someones drilled through the cable

If you have a fault then someone is definately to blame and you should have some kind of comeback; you could threaten whoever installed it with reporting them for not complying with Part P of the building regs as it should have been installed be an electrician from the start.

 

[sparkyspike]

As nozspark mentioned, the mat is tested before tiling and the results written down. The mat is then tested after installation of the tiles and the results compared. This is the normal proof required that a mat was faulty before installation.

 

[sparkyspike]

we have installed underfloor heating below a ceramic tiled kitchen floor.

Perhaps you should have installed a ceramic tiled kitchen floor over underfloor heating. It would have been easier!

 

[jkrikler]

i think the guys we used wore ten gallon hats... but the fact of the matter is that even if we could get it sorted we wouldn't want the disruption of taking up the floor etc.

if there's a chance it could be an electrical issue that is potentially able to be solved i'll try that but beyond that i think we'll just have to accept the situation (at least until my wife's bored of the tiles she chose...)

thanks for all the advice - if we do ever do this sort of work again i'll make sure we get it right!

 

[Taylortwocities]

The above is correct. All ufh mats I have seen have clear instructions that the mat should be tested before and after installation.

Curious that it worked for couple of hours, it sounds like it tripped when the mat had got to temperature and switch off otherwise the problem would have shown at switch on.

I does need a decent spark with the correct test gear to analyze before you totally despair.

I guess its a case of cheap work isn't good and good work isn't cheap.

 

[Softus]

And cheap work isn't actually cheap, either.