Underfloor heating, temperature sensor probe resistance

[stevenmccaw]

Hi,

I'm glad i found this web site. Some of the information on other posts has been really helpful thanks.

I'm installing underfloor heating wires on warmup insulation boards. tiling with 30 x 60 porcelain tiles directly on top.

The instructions for the thermostat advise to cut a channel in the insulation boards to insert the temperature sensor probe. i am advised to check the resistance, and it should be between 8 and 12 ohms, at 20 - 30 degrees. The room is fairly cold, I would guess about 15 degrees. Trouble is the resistance is comming out at 15 ohms.

Does anyone know if this is going to be a problem?

Thanks.

 

[hairyben]

Probably okay.

There are different types of thermister, some gain resitance and some lose it with temperature increase and I'm not sure what warmups do. I'd advise asking warmup themselves to be certain- there'll be a technical helpline on warmups website (or phone the normal line and ask for tech)

 

[stevenmccaw]

Thanks Ben.

I was hoping it was to do with the room being colder than on the instructions. I'm just about to tile, and warmup are closed. So hopefully it is ok.

Thanks for the prompt reply.

 

[ricicle]

Probably okay.

some gain resitance and some lose it with temperature increase

Positive and negative temperature coefficiency

 

[GaryMo]

Don't forget to read section 753 in BS7671:2008 (p224) regarding installation of electric floor systems.
There's quite a bit of information, including plans, which need to be fixed by the consumer unit which supplies the heating system.

 

[sparkyspike]

Are you sure it's not the heating cable you should be measuring? The manufacturers usually ask for this to be measured in order to compare pre- and post-installation measurements in case of damage.

 

[electronicsuk]

Why all the hassle? Just warm up the sensor probe in your hands and then measure it.