Underfloor Heating

[longdogs]

Hi

I'm currently installing and tiling an upstairs ensuite. The customer has asked for a Warm up underfloor heating mat to be fitted. The laying of the mat all seems straight forward but as I am not an electrician I will need to get a sparks in to complete the wiring. I want to finish the floor tiling and the walls first though. I can test the circuit myself before laying them.

My question is: What do I need to prepare for the electrician? Is it just a case of running the cable into the wall and up to a back box (outside the room) and then running another cable from the back box to the loft.

I havn't seen the instructions yet but just wanted to get the heads up.

Thanks

 

[RF Lighting]

Do you have an insulation tester and a multi meter?

Get the sparks onboard first so he can tell you where the cables in the floor and walls need to be run, and to make sure the mat you have bought is suitable for use in a bathroom etc.

It's not going to be great if we advise you wrongly on here because of something we didn't know about from not being able to actually see the job, and you have to take all the tiles back up to sort it out.

 

[ericmark]

I have fitted one and it was a flop. So learn from my mistakes.
1 - The pocket (That's the tube the temperature sensor slides into needs a very shallow curve and testing first before you tile as with the one I did the sensor got stuck in the pocket.
2 - Need to have paperwork to say suitable for bathrooms.
3 - Needs a smooth tile not sculptured I found drying time with sculptured far too high.
4 - Needs some other form of heating as well. With tiles just cool enough to walk on it still did not fully heat the wet room.
5 - Because of the earthed outer they are near impossible to repair and if it does fail it's a remove all tiles and start again job.

The one I fitted in my Mums wet room is now never used. The idea was to dry the tiles so my Mum was not moving on wet tiles with one leg. But once wetted with shower it took 20 minuets to dry so she had left the room well before then.

Lucky a towel rail was fitted. Think from memory the max temp of floor is around 35 degrees so only a 15 degree temperature difference where with a radiator more like 70 degrees so 50 degree temperature difference plus the radiator circulates the air better than the floor. With the required fan running drawing air from outside it was useless. One would have to fit a heat exchanger to recover the heat which really bumps up the price.

 

[bernardgreen]

All that Eric said and more.

Hot water under floor heating is a better option.

Find out the temperature that is reached if the control fails and leaves the heating mat permanently on without the thermostat controlling the temperature.

 

[pjcomp]

Give the UFH tech support a call before getting the matting and talk to them. If it's going to work it needs the right mix of insulation beneath the mat and the right size/power of matting for whatever's going on top of it, there's no one size fits all. For a start, they'll ask you if it's going to be the primary room heater or a secondary, just to keep the floor warm. I'm not a fan and I've never recommended it (cost of the kit, cost of running it) but I've met people who swear by it and who swear at it in equal numbers.

PJ

 

[Taylortwocities]

Its electrical work in a bathroom.

Its notifiable

You'll need a registered electrician to do this work for you

The power feed to the heating mat will have to be RCD protected

Dont forget you'll also need to provide a cable route from the floor element and the probe to a controller

 

[SimonH2]

The instructions for the Warmup kits includes how to test the mat and sensor. After laying, you should test the mat for insulation resistance, and heater resistance (the value for which should be in the instructions). The sensor should also be tested - just resistance for this. You should recheck these periodically during tiling.

Having read the instructions, I reckon I could repair a wire using their kit - but it's not something you'd want to do without a bit of experience (ie it's not a novice level task). The hardest part might be finding the fault if it's not obvious (ie you know you "got" the wire with a trowel edge.

 

[TheGayOwl]

I have the WarmUp UFH at home. It provides nice supplementary heating in the winter, in what otherwise would be cold rooms.

As said, speak to the spark connecting it up, as they will have their own view on proceedings. Safe cable routes need to be adhered to, the spark can advise. There are also other considerations such as adequacy of current earthing.

If he/she is happy for you to lay the heating wire then fine. But be careful with it. I would recommend making sure the floor is scrupulously clean and snag free. I would also not trample over it in shoes either.

I also did the tiling on ours and I tested the resistance of the wire regularly, so if there was an issue I could likely pinpoint it to a specific area. The resistance was around 67 ohms if I recall - measured with a multimeter.
I do not recall having to IR test it.

I know of a few people who have ducked it up...that said WarmUp used to have a policy of a free repair on a damaged cable...do not know if they still do though.

If I did it again I would fit the thermally reflective sub-floor also. I have found that 'aerated' travertine tiles do not heat up as quickly as 'non-aerated' slate tiles.....if you get what I mean.

 

[SimonH2]

I know of a few people who have ducked it up...that said WarmUp used to have a policy of a free repair on a damaged cable...do not know if they still do though.

I think they still do - limited to one repair, and conditional on you informing them (and stopping tiling) as soon as you discover the fault.

While there's nothing in the destructions about IR testing, if you have the capability then I'd suggest it's worth while - failed insulation is just as much a show stopper as a broken heater wire.

As an aside, do not be tempted to think you can chop a bit of wire off it's it's too long. Apart from the issue of how to remake the end correctly, there is a minimum length for each grade of wire. It's a single pair of resistance wires, joined at the dead end - so half the heat is from the live wire, and half from the neutral return - and the joint at the end will be at half the mains voltage. If you chop a bit off, the resistance will be lower, and the power dissipation higher.

When we did my mates bathroom, we used the loose wire version so we could arrange it round the odd shapes and leave gaps where the toilet and sink pedestal could need holes drilling. We also took photos and measurements so we know exactly where the wires are.

 

[HH1]

On the subjuect of installation and cable damage :-

There is a gadget you can get now which is connected to the wiring during the installation and will alarm if the cable gets damaged.
Could be used in addition to the multimeter testing.
Believe it's called a "screamer", should be able to get it on ebay.
Certainly some suppliers are supplying one free with their kit.