Wiring **** underfloor heating sensor?

kev3 · Post by **kev3** » Sun Mar 25, 2007 6:42 pm

Hi guys,

Need some help with my warm up underfloor heating!
Just finished wiring up the supply via rcd and load to heating element, but have got stuck with the sensor as it is just labelled as 7 and 8 with no clear reference in the instructions as to which wire goes where?!
Any ideas?? I have just put them in 7 & 8 for now, but do not have power running to this circuit.

i'll try and post a pic here:

sparkydude · Post by **sparkydude** » Sun Mar 25, 2007 6:52 pm

The way you have it connected is fine, if you look at the picture on the back if you had 2 sensors in the system they would be connected in series, as you only have one, the terminals you have used are fine.

Nick

kev3 · Post by **kev3** » Sun Mar 25, 2007 8:52 pm

Thanks Nick!
Do you think it matters which way the current flows for the sensor?
say if i put the brown wire in 7 and blue in 8 would this make a difference?

sparkydude · Post by **sparkydude** » Mon Mar 26, 2007 9:20 am

I would not have thought so, as if it mattered then they should say so in their instructions, after looking at them on the net they are vague to say the least. It is after all only a switch that operates dependant upon temperature so i dont think it is polarity sensitive.

Nick

Slugster · Post by **Slugster** » Mon Mar 26, 2007 9:27 am

Kev3, This is exactly what I fitted.

The sensor works on resistance so it doesn't matter which way it's wired.

They advice slapping a mutli meter on it to check it works before over tiling it.

I had a great time checking out what effect the temperature of various body cavities had on it

kev3 · Post by **kev3** » Mon Mar 26, 2007 10:20 am

Thanks guys!
Looks like i won't be blowing the mains ring when this circuit goes live!
Slugster.. interesting ideas! i agree it is important to test the sensor is working now where will i stick it?

kev3 · Post by **kev3** » Mon Mar 26, 2007 1:39 pm

One last question on this guys!
You see the load terminals 3 and 4 this goes to the heating element which also has an earth connection but this thermo stat does not have an earth terminal!
So i have wired this earth connection (you can just see it bending up in the pic) to the RCDs earth terminal.. is this correct?

Slugster · Post by **Slugster** » Mon Mar 26, 2007 1:43 pm

Kev,

You'd better wait for Sparky (see my post on Earthing I ain't an expert) but I wired mine (I have two heating elements from the one controller) to the back box earth point which is connected back to the main earth so I guess it's the same thing.

So I'll be interested in the reply as well. But my heatings been working for 2 years without killing us or the cat - yet

sparkydude · Post by **sparkydude** » Mon Mar 26, 2007 4:22 pm

Yes thats fine, as long as you have earthed the cable by connecting to one or other of the earth terminals in the RCD then its fine. the thermostat is double insulated as shown by the square inside a square symbol so does not need an earth connection, but if one is present in the wiring system then this must be made continuouus.

Nick

kev3 · Post by **kev3** » Mon Mar 26, 2007 5:19 pm

Many thanks again Nick!
I was wondering what that square box meant!

I think they just included the earth connection on the heating element to confuse people when they come to wiring up the thermo stat!
but to me it seemed logical to connected to the rcd earth as they recommend that the supply comes via one and there was nothing else to connect to that earth connection on the rcd.