Underfloor heating/issue with builder

[thickbed]

They put a high voltage through the mat and used thermal imaging to detect the fault so I assume the original failure didn't look as bad as it did but by sending a high voltage through the mat it explodes at the weakest point and in this case was my taped over end join. Is this right ?

 

[Old Mod]

Also does anyone know what this means- it was one of the notes on the bottom of the report

Resistance reading less than 999Mohms of heating element to braid (or earth) indicates heating element
insulation damage. Heating cable in working order although low resistance reading may deteriorate and cause future
failure. Fault location not attempted with element to braid (or earth) resistance above 10Mohms due to risk of damage
to heating cable. IEE Wiring Regulations require minimum insulation value of 1Mohm for general supply wiring

If I'm correct, they take a resistance reading between the cable core and the outer braid. (The metal strands that surround the core and core insulation.)
It has to be a certain value to ensure proper insulation is present.
Get @Dan to link this thread to the sparks forum, they should be able to answer your questions.

 

[Uheat - Jake]

Also does anyone know what this means- it was one of the notes on the bottom of the report

Resistance reading less than 999Mohms of heating element to braid (or earth) indicates heating element
insulation damage. Heating cable in working order although low resistance reading may deteriorate and cause future
failure. Fault location not attempted with element to braid (or earth) resistance above 10Mohms due to risk of damage
to heating cable. IEE Wiring Regulations require minimum insulation value of 1Mohm for general supply wiring

If there was a break in the cable it would have been showing open circuit on the multimeter.

They put a high voltage through the mat and used thermal imaging to detect the fault so I assume the original failure didn't look as bad as it did but by sending a high voltage through the mat it explodes at the weakest point and in this case was my taped over end join. Is this right ?

This is a common way to find a fault with the heating element, it's a very complicated procedure especially if you don't know where the fault is.

 

[Dan]

@thickbed can I assume that if we are still going on about this now, that they did indeed contact you before they went ahead with the repair and you refused to go look at the job or said it wasn't your job to or something and now you're just trying to pass the blame?

Reason I say this is because if you didn't have the chance to repair a fault of yours, or at least be involved in agreeing whether repair costs are appropriate, it's not something you need to carry on worrying about.

And you keep skipping past me pointing this fact out.

So I'm starting to think you perhaps did have the opportunity but avoided it maybe?

If that is the case, just split the bill with the builder and swallow your pride and move on.

But don't wriggle out of it.

Perhaps go on a UFH installation course and learn about it. Or avoid installing it in the future.

 

[thickbed]

@thickbed can I assume that if we are still going on about this now, that they did indeed contact you before they went ahead with the repair and you refused to go look at the job or said it wasn't your job to or something and now you're just trying to pass the blame?

Reason I say this is because if you didn't have the chance to repair a fault of yours, or at least be involved in agreeing whether repair costs are appropriate, it's not something you need to carry on worrying about.

And you keep skipping past me pointing this fact out.

So I'm starting to think you perhaps did have the opportunity but avoided it maybe?

If that is the case, just split the bill with the builder and swallow your pride and move on.

But don't wriggle out of it.

Perhaps go on a UFH installation course and learn about it. Or avoid installing it in the future.

Don't know why you now assume that I was contacted before the repair had taken place and trying to get out of it, the first I knew of this situation was the email from the builder asking for me to pay the repair guys. He went ahead and got the repair done without me knowing about it.
I am still gobsmacked that he has gone about it in this way-why not phone me first.
The reason I am going on about it still is that I am now starting to question the verdict of the repair guys. I honestly believe that by putting some masking tape over a join, it would cause it to burn out. From what I can see in the picture that has been sent to me by the builder the tape around the join was tight to it and was encapsulated in levelling compound afterwards and then tiled over.

I have spoken to a few sparkies about this and all of them say this is near impossible to happen. Anyway all of this is irrelevant because the builder has not contacted me in the first instance.

Who is going to replace the 2 tiles and whoever that person is, are they then responsible for the floor?

Think that was a bit of a low blow suggesting I go on a UFH course. I have done hundreds of UFH installs and this is the first one that I have been blamed for and I want to know why!
The builder has given me to this Friday to pay his bill or he will take it to court

Mike

 

[Dan]

Hi Mike,

Apologies if I touched a nerve. Didn't meant to, that's for sure. We're here to help.

He doesn't have a leg to stand on in court. So go, and present your case, he'll end up paying court costs. Don't avoid going though, he'll automatically win.

Simply say you'd have been more than happy to repair the UFH and the tiles as a result, but as you were neither consulted or offered the chance to repair yourself at your own costs, which you're quite capable of organising, you are simply not liable to pay somebody else's bill to which you had no control over the value of.

In fairness, if I were you, I'd split the costs and walk away with your head held high.

It's 180. Stick it through your business as an expense and offset it against your tax bill and it works out even less. If you're VAT registered claim your % of the vat back and it's even less. And in the long run if the word gets around (and you don't get the opportunity to have your say) locally, it'll cost you more in possible lost business.

 

[Spare Tool]

I disagree Dan, I think he'll walk out of court head held high when he wins his case, not by splitting the £360 with the builder.
So say a tile had cracked and the builder didn't contact the installer, instead he flicked through the yellow pages and ended up picking @impish to do the repair...imp hits the builder with £500 bill for his half a day the builder then expects the installer to pay that bill, even though he was quite capable of changing the tile himself...its not on and the builder's only got himself to blame!!

 

[Dan]

Oh no I'm totally down that way of thinking mate read my posts in this thread it has only been me banging on about that fact.

But the OP keeps coming back with more 'what ifs' and so i thought if he's fighting it like that he won't make himself look cool locally. So just pay some or whatever to keep the cool.

But yeah I'd cut the builder out, and explain to the customer the situation and ignore the builder directly and wait for the hearing.

 

[thickbed]

I honestly believe that by putting some masking tape over a join, it would cause it to burn out. Sorry this is wrong and should have read:

I honestly believe that masking tape would not cause this to burn out

Mike

 

[Dan]

Shot yourself in the foot doing it anyway if it says not to. Even a manufacturer fault wouldn't hold if you'd not followed the instructions to the T.

So personally, I'd drop it and just go to the hearing.

 

[One Day]

I don't charge half days. 10 mins or 8hrs. All the same to me...!

 

[mache]

So just as a matter of interest how many people installing electric UFH cables after reading this thread will tweak just a little how they install. even if its just to tape either side of the cold termination rather than directly over it ?? I'm just DIY and curious but it did make me think back on how I installed by bathroom mat. (I then remembered that I had used the hot clue technique)

 

[Dumbo]

So just as a matter of interest how many people installing electric UFH cables after reading this thread will tweak just a little how they install. even if its just to tape either side of the cold termination rather than directly over it ?? I'm just DIY and curious but it did make me think back on how I installed by bathroom mat. (I then remembered that I had used the hot clue technique)

I've tweaked mine already as I had exactly the same problem with thermonet heat mat

 

[Old Mod]

I've tweaked mine already as I had exactly the same problem with thermonet heat mat

Yeah, we know!

 

[thickbed]

Hi All

Just an update to this situation- I reluctantly decided to pay this, although I still find it hard to believe that masking tape stuck over a join can cause enough heat to burn it out! however the instructions say not to cover the joins so I accept this is an installation error. I also spoke to the consumer helpline people and they said that as the main contractor, he was correct with what he did re the repair and was his right to do so (which I also disagree with). So thank you to all those people who shared their thoughts on this-much appreciated.
Regards
Mike

 

[andy8758]

Thickbed. Thanks for sharing your experience- I have attended various training events and installed loads of ufh systems. But this made me review my practices. Ur a top tiler for that in my books

 

[Spare Tool]

Hi All

Just an update to this situation- I reluctantly decided to pay this, although I still find it hard to believe that masking tape stuck over a join can cause enough heat to burn it out! however the instructions say not to cover the joins so I accept this is an installation error. I also spoke to the consumer helpline people and they said that as the main contractor, he was correct with what he did re the repair and was his right to do so (which I also disagree with). So thank you to all those people who shared their thoughts on this-much appreciated.
Regards
Mike

This is one I would love to see on Judge Rinder ..but fair play to you for paying repair bill.

 

[Kyle Knowles]

If that crimped end is such a issue why is it being manufactured in that way surly it come out the box with some kind of conduit on the end ?? If it's a issue why not eliminate the issue at the design stage ?? Or am I being stupid? ?? It wouldn't be the first time haha

 

[andy8758]

I did my Part P exams back in 2008. One of the key issues with siting any electric cables is consideration of how heat is disapated - there are whole appendices to the 17th wiring regs on that. To cut a very large amount of info down, manufacturers of electric appliances have to give very precise information on installation, that should be followed.

In this case the weakest parts of the underfloor heating cable is at the joint between the cold tails (electric supply cable) and heating cables, and the crimped end of the cable. So the manufacturer of the ufh cable may stipulate precise instructions on how and where those parts must be installed. If the manufacturer glued the ends, then the joint may be susceptible to overheating, but brazed joints may be less vulnerable.

But I got to say I don't recall reading instructions that said "don't tape the crimped end" nor do I recall during training with 3 different ufh reps, this point being made clear. Now I know this, I will re-read instructions with the next installations due at the end of this month.

 

[thickbed]

I suppose as installers we don't get to see how well the joins have been crimped in the factory. The 2 joins on the mat have shrinkwrap on them and are a form of insulation anyway so what I struggle to understand is how masking tape can be enough of an insulation to stop the excessive heat buildup to transfer through it and cause it to burnout!

 

[SJPurdy]

I struggle to understand is how masking tape can be enough of an insulation to stop the excessive heat buildup to transfer through it and cause it to burnout!

It is not the tape that traps the heat but when tape is put loosely over the wire joint then there will be a trapped air filled void which will then itself be surrounded by SLC or addy. Where the SLC or addy is in direct contact with the heating wire (joint) then heat will flow through it away from the wire. However where there is a trapped air pocket around the wire(joint) then the heat does not flow through the air very well (compared with the SLC or addy) and thus bit of wire(joint) might overheat.