22mm ply onto joists, ufh, which board to use and why? - TilersForums.com

[Uheat - Jake]

Thanks for the replies guys, although slightly conflicting lol, I've suggested the hardifloor and tbh am quite keen to give the product a go.

On another note Ufh, biggest matt sold I can find at the moment is 12m2 roll. I havent installed anything bigger than this, I'm guessing its possible to combine matts? meaning you can run them all to one thermostat or something?

You can have numerous mats off one thermostat, however you need to think about a difference in temperature from one side of the room to the other if it's a big area and espcially if it's a kitchen / diner, as you have to take appliances into account as they generate heat and could cause contradiction on the thermostat leaving the other half of the room unheated.
A normal electric ufh stat can take up to 16amps which is 22m2 of 160w/m2 mating.

 

[Rookery]

You can have numerous mats off one thermostat, however you need to think about a difference in temperature from one side of the room to the other if it's a big area and espcially if it's a kitchen / diner, as you have to take appliances into account as they generate heat and could cause contradiction on the thermostat leaving the other half of the room unheated.
A normal electric ufh stat can take up to 16amps which is 22m2 of 160w/m2 mating.

Please will you clarify. Surely it's the latter not the former?

 

[Uheat - Jake]

Please will you clarify. Surely it's the latter not the former?

Should have made that a bit clearer, the biggest single mat we do is 10m2 in any wattage, therefore to get to 22m2 you need to make it out of three mats which are then wired in parallel to the thermostat. However if you require more then 22m2 of mating then they can all be wired to a contactor, a contactor will switch the load down to under 16amps which the thermostat can then handle, enabling you to have 30, 40 or even 50m2 off one thermostat.

 

[Flintstone]

Only a week or two ago I fitted 2 x 15m kits down. I'm sure I've used a 19m kit before as well. Remember you need to calculate the area right, not just the size of the room.

 

[Flintstone]

Personally i would over board with 10mm insulation board over the 22mm ply, this will decouple and insulate. I don't think there's any need to over complicate with multiple layers of ply wood etc.