Underfloor heating mat

[BigSi]

I’ve been asked to lay an underfloor heating mat in a bathroom as part of a new build. Now I’ve never actually installed a mat before, so I was hoping you guys might be able to give me a few pointers.

Now I know about the spacing and how to cut and lay the matting, but does it get laid straight onto a wooden floor, then covered in flexibly tile adhesive and then tiled. Or do you lay some form of insulation between the floor and matting? Also where do you site the thermostat?

Any help would be much appreciated.

 

[white armour]

Hi BigSi, have wired in a couple of UFH systems for a tiler mate of mine. Think what you put on or under the mat depends on the make/ model of the mat you wish to install.

Check the paperwork that comes with the kit or do an online search, this should give you the info you need.

I always install FCU or RCDspur & stat outside of the bathroom as there is usually plenty of cable supplied.

Regards wa

 

[Dunc]

If it's anything like the kits i've used you prime the floor (usually plywood) with this green liquid, leave it to dry then tape the element straight down. The tiler then just adhesives and tiles over it. Make sure you IR and continuity test the element before and after tiling. Spoke to a Warmup Engineer recently who suggested IR testing the element at 1000V as this is more likely to show up small faults that the 500V test may miss.

 

[IQ Electrical]

Yes, most manufacturers have a warranty card and the IR and continuity readings should be entered on the card and left with the customer-without the readings, the warranty is invalid.

 

[Dan]

We get special prices from Underfloor Heating | Electric | Floor Insulation | Frost Protection | Uheat if you're interested mate. Mention your from the electrical forum and tell them Dan sent you.

Though as for the matting, you pretty much just lay it out 100mm from the edge of the room. Never cross the cables or have them sitting really close. If you need to, pull the cable off the matting on the last bit to make smaller or bigger loops.

You can buy a gizmo you attach to the cables that bleeps or something if you damage it (and there's a break in the cable somewhere) so you know to stop, and you should know which bit is damaged. (They're pretty tough to be fair though).

I'm guessing somebody else is covering it with SLC or something then?

 

[Bradzz]

YouTube - Underfloor Heating - Part 5 - Laying matting

THIS MAY HELP

 

[Short Circuit]

...and dont forget to make sure you get the right mat for woodfloors, ie 100w per sq mtr, not the 150w which is for concrete

 

[BigSi]

Thanks for the great info guys.

So basically as it’s a wooden floor, I need to screw thermal insulation boards to the existing floor to focus the heat up into the tiles (quicker warm-up time, less energy). Then lay the matting (100w) and floor sensor (inc testing), then cover with flexible tile adhesive, then tile (compatible with underfloor heating). Then position the SFS and thermostat outside the bathroom.

I can’t believe I’ve never done one before!



PS: Great vids on YouTube! Liked the bit when she thought she would get a shock!

 

[Short Circuit]

yep, thats about it really! I havent seen that you tube clip yet, so not sure of its mentioned it, but i would advise on putting the controller at switch height, some people say put then at low level next to the spur or rcd but that makes it a nightmare to programme!