Electric UFH - bunching cold tails

[James Carmichael]

Hi all,

I'm running electric UFH. (Yes, I know opinions vary about usefulness ... let's just go with it!)

It's a 16m^2 area and I'm using loose cable. I have 2 reels. This means two cold tails.

I know the heating cable itself should not get closer than 50mm but is there any reason I can't bunch the cold tails? To avoid channelling plaster, they'll be routed through a solid block wall to a neighbouring utility room, before going back through the wall to the thermostat.

Based on length of cable, each tail will be carrying around 5.5amps. I have no idea of the CSA of the tail but I assume it's been sized for that load.

Can I run both tails and the tail from the temperature probe in the same 20mm plastic conduit - let's say total length 3 metres - or am I likely to be derating the capacity of the tail unacceptably?

Thanks

Phill

 

[ericmark]

Seems likely you can run both together, but electric underfloor heating comes as two very different types. Chemical and resistive wire, the chemical is reasonably self regulating, as temperature raises the resistance increases, so putting things on the floor will not cause over heating, and the power varies with temperature of the floor, RayChem for example, but the resistive is not self regulating and needs sensors in the floor, the sensors do fail, so you need pockets for the sensors, i.e. a tube which the sensor and wire can be removed and refitted if required, they do not like going around sharp corners, so would always test they will slide in/out of pockets before the pockets are fixed, and the sensors do not tend to have very long tails, so it seems unlikely you can put the cold tails together as the sensors which go with them will be unlikely long enough to group together.

 

[James Carmichael]

Thanks Ericmark. I spoke to the supplier today (I'm using Warmup stuff - no affiliation) and they said it was fine to run multiple tails in the same conduit up the wall so long as the joint between the cold tail and the heating element was fully encapsulated in SLC or tile cement.

I didn't ask about the probe too as my routeing plans have changed!