Underfloor heating/issue with builder

[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.