Electric underfloor heating mat to big!

[triggersbroom]

Hi,

In a dilemma about this. My builders have fitted an electric UFH mat in my kitchen/diner - actually 2 of them to cover the area, each mat is 9sqm. They are the silver foil type with the wire/element running through.

We've got to the end of the room, and he's been laying engineered wood floor on top as he goes. There is an excess of mat about 1m long, the width of the mat is 50cm.

Yes I know, I know: it should have been laid out completely in the first place and we should have exchanged the mat for a shorter one, but it's tricky to know as you have to cut the foil to get round corners etc.

The builder suggests we run the excess up the wall behind the kitchen cabinets (near the sink as it happens). I spoke with the suppliers and they said that is a possibility, but I have no idea how much heat these things put out. Am I letting myself in for problems in the future like the worktop (oak) warping or anything? Plus of course we'll end up with a rather warm cupboard I assume.

The supplier also admitted that although it would invalidate the warranty, (and against everyone's advise I've ever seen on this!) you can cut the actual wires and crimp them (whatever that means), shedding up to a maximum of 1m of excess. My concern here is that you are altering the resistance of the mat and as far as I can tell that might lead to overheating problems - though the supplier didn't mention this I assume that's why the 1m limit.

So I just don't know what to do for the best. Yes, ultimately, the wood floor should come up and a shorter mat be laid, but it's T&G and he's glued every other board, so this is very much a last ditch solution.

I'd very much appreciate any thoughts or advice.

Thanks!

 

[1john]

The meter of cable that you can remove will be linear of the cable, not a meter off of the length of the mat. It sounds as if the floor needs to come up and a correct mat purchased, certainly do not cut any significant amount off of the mat. Why on earth wasn't the mat laid out before installation, It can always be rolled back up again. Another way is to simply work out the area you need to cover and see if the area of the mat fits in it. Is your builder doing all of the electrics for this flooring, if so I would be worried.

 

[digdilem]

Oops!

You are absolutely right to be cautious of cutting/crimping, that sounds very dodgy. Supplier is not the manufacturer and could have no understanding of the product at all.

Running up the wall is a bodge, and one day somebody'll drill through it. If it's mains current it could breach the regs (someone better informed than me will probably shout out on this.) Also - I don't believe a 90 degree bend would have been factored into the design and could cause a stress fracture.

Only proper solution is to start over. Sorry. If the builder is responsible for the job, it's his responsibility to do it right and cover any costs involved. Sounds like he's trying to shift the burden onto you. Be firm!

 

[triggersbroom]

Thanks guys.

Yes, I measured it wrong in the first place obviously, because I ordered the mats. But he should have checked properly too so I think it's shared responsibility really.

I'll go back and ask the time/cost implications of having the floor up and re-laying.

You're right, it seems cutting it off is out of the question.

Worst case scenario, having it behind the kitchen unit seems the only way. I'm not too bothered about this other than as I said, I have no idea how much heat these things put out and that's my worry. We won't be drilling/screwing anywhere near it in future.

 

[1john]

You may find that the mat is not designed to be in free air behind a kitchen cupboard. You need to contact the manufacturer technical department, the supplier will have these details and hopefully you wont need to ring china to find out.

 

[triggersbroom]

Yes - too many 'what ifs' for my liking. Have ordered a new smaller mat, builder has agreed to re-do it I'd that's what we want.

Thanks for the opinions.

 

[digdilem]

Right decision, even if it costs more you'll not have it nagging at the back of your mind.

 

[Steve]

If this is the main source of heating in the room it will cost a fortune to run.

 

[cozzmic]

You can cut the element off the mat and lose it on the floor. It should be in the instructions telling you how to do it as no rooms are exactly what you need. you either have a bit too much or too little where you have to re-space it out to fill the missing gap.

 

[coliholic]

Since you've already been in contact with the supplier over this issue, why not get them to give you a price to come and cut it. But you want ot done tomorrow. Not in 6 months time.

And if they won't do that get them to e-mail you detailed instructions as to how to cut it and what crimp etc to use then go to your local electrical factors and buy the bits and DIY as per their instructions. Take loads of pics as you do it for any possible future arguments.

Or ask 'em your factos for a recommendation. They'll have a load of names of lectric ians who you can pay a few quid to come and do the work. Bank on £80 an hour if you're not in London and about a half hour job I reckon.

 

[judgewilz]