Electric Underfloor Heating Installation

[Midwest]

I've been asked to install some electric underfloor heating, as part of a bathroom refurb. Never installed the stuff before myself, in fact 'cos of some of the nightmare stories I've read here, I've managed to avoid it. However, got to do it this time. I was wondering if those that have put some in, could offer some installation tips, or do's & don'ts.

Customer will be providing the matt & controls, he wants a particular thermostat, which is WiFi connected. I don't know the manufacturer at the moment. The heating is going in a small 1st floor ensuite, about 2m square and may have a tiled walk in shower. He wants the tiled shower area heated, which I'm not sure is possible, due to the gradients of the base?

I've read about testing continuity before and after tiling. Subfloor will be chipboard overlade with 18mm ply, and whatever tanking is required. I see that most manufacturers suggest installing conduit for the sensor, what do you use?

Advice appreciated.

 

[Octopus]

my top tip is don't let the customer supply the parts .....

you need a decent stat, and a matt which is laid out on a backing - avoid the ones which you have to layout in one core all around the area....

Call a manufacturer like WarmUp and see what they say about the shower area.

Who is doing the tiling?

 

[telectrix]

best way is to get the tiler to lay it .you test before and after and commission it. that way, if it gets damaged at any time, tiler's responsibility.

 

[Midwest]

Thanks Murdoch, I understand the parts thing, but the guy is a bit of a geek, and wants a particular controller so over to him. Should get the matt manufacturer today.

Doing the job for my son's business, so they have a tiller.

 

[Midwest]

best way is to get the tiler to lay it .you test before and after and commission it. that way, if it gets damaged at any time, tiler's responsibility.

I like the idea of shifting responsibility. Not sure if I trust the tiller, but good point.

 

[telectrix]

it's what i do.test element continuity and IR..... 1.before laying, then 2.after laying but before tiling,then 3. after tiling,....showing the tiler the readings each time.

 

[Octopus]

I test the matt in the box, after its laid and on completion - that way its easy to spot when it gets damaged. Sure it means extra 10 minute visits but worth while.

 

[Midwest]

Re the senor cable, running in conduit, isn't a bit of 20mm bit big Oval conduit?

 

[Leesparkykent]

If you want to go in the shower area then a single wire kit maybe the way forward.

 

[The Ghost]

Call a manufacturer like U Heat

Corrected that for you.

 

[The Ghost]

Try to map out exactly where the sensor is going in order to make sure a groove is made for the supplied ducting (12mm roughly) and consider putting in two sensors, one as a spare. They do go and its a failsafe back up. Manufacturers will say if it's 2 sq m. then get 1.5 sq. m. However measure very carefully, although you need to leave a space around the edges and obstacles you should attempt to get it as close to all edges as possible. If it's a hard shape you can get two smaller mats as the controller can control more than one mat.

 

[Midwest]

Try to map out exactly where the sensor is going in order to make sure a groove is made for the supplied ducting (12mm roughly) and consider putting in two sensors, one as a spare. They do go and its a failsafe back up. Manufacturers will say if it's 2 sq m. then get 1.5 sq. m. However measure very carefully, although you need to leave a space around the edges and obstacles you should attempt to get it as close to all edges as possible. If it's a hard shape you can get two smaller mats as the controller can control more than one mat.

Is that two in one ducting or two separate sensors & ducting ? Do all manufactures supply a ducting?

 

[The Ghost]

Don't know if all do but the three different manufacturers I've use do. There is enough ducting to put two in. I guess it's a case by case base for in one or two ducts.

 

[AJshep]

Apart from what's been mentioned I always take a photo of the mat once it's laid and do a sketch of the layout.

We had a builder install a heat mat recently, and they ended up putting the floor prob to close to the mat, so the stat kept cutting out as it thought it was up to temp.

They managed to speak to techinical and set the stat to work on air temp only, but we omitted it on our EIC because in Section 703 it says about the the floor temperature itself needing to be limited to 80°C, and the system should be able to limit the floor surface temperature in areas where people will walk.
When we phoned techinical they said this could be only achieved by using a floor probe.

So hopefully your customer gets the right stat, another thing is I believe different manufactors use different resistances for their floor probes.

 

[Midwest]

My customer is using 'thermonet' heat matt & their 'thermostouch'; thermostat Underfloor Heating - Thermogroup - http://www.thermogroupuk.com/products/underfloor-heating/. The manufacturer also do a matt specifically for shower trays to accommodate drainage, and are IP68 rated. Still not convinced on how the matt can be formed, to follow the contours of the drainage for walk-in showers (tiled), but guess its flexible. Need to speak with manufacturer & customer about that. Matts supplied with flexible conduit for sensor.

Instructions for testing before during installation etc.

Seems a piece of ---- (note the sarcasm smiley!)

 

[Sparkie30]

Installed this recently Schlüter®-DITRA-HEAT
german kit came with floor sensor and stat also you space the cable as wish. Test cable after laying it take picture of reading. Very good stuff.