UFH resistance checking.

[Sean Kelly]

I have searched high and low for instructions on how to test resistance on my Uheat UFH mat.
I bought the mats & multimeter from Uheat, but not too sure on how to use it. I set the multimeter dial to 200 ohms and plugged the leads into the COM and VΩmA holes. The other ends of the leads were touching on the live and neutral leads of the mat. I got 2 different readings from the 2 different sized mats. Reading one (small mat) was 41.1 and the other (large mat) was 31.4. Does this sound right?</SPAN>
Everyone is saying that laying the mats is easy, but this is my first time. I also bought the monitor, which will alarm if the cable breaks. Cheers Sean

 

[Gazzer]

Yes you will get different reading s depending on mat size. I am sure the readings were on the box when i used their system.

 

[Gazzer]

This should help you out
http://www.tilersforums.com/electric-underfloor-heating/19140-ufh-testing.html

and this
http://www.tilersforums.com/electric-underfloor-heating/19146-u-heat-cable-resistance-readings.html

 

[Sean Kelly]

Thanks Sir Ramic. Exactly what I was looking for. The small mat states 41. I get a reading of 41.1. The large mat states a reading of 33. I get a reading of 31.4. Is the 31.4 an acceptable reading? Cheers Sean

 

[Gazzer]

Yes mate that wil be fine.

 

[bert&ernie]

Hi Sean,

The allowed tolerance is generally +/- 10% so as Sir Ramic has said you are fine. If you are ever unsure just give the guys at uheat a call and they will be happy to help

to hopefully help a little more you can work out the Resistance for yourself.

you first need to work out the Current (Amps) to do this you need the total Power (W), so for example if you have a 5m2 mat @ 160w/m2 then your total Power will be 5*160 = 800W.

You then divide this by the uk power supply (230v) 800/230 = 3.48Amps

You can now work out the Resistance (Ohms) by Dividing the Power supply by the Current. 230/3.48 = 66.09 or 66 Ohms.

Hope this helps and i have explained well enough.

 

[dagger]

make SURE when you attach the probes from the multimeter to the wires on the heat mat, your fingers are not touching the wires or the probes,
this will give you strange readings!!!

(you know, the bare metal parts, and the copper wire!)

 

[faithhealer]

Everyone is saying that laying the mats is easy, but this is my first time. I also bought the monitor, which will alarm if the cable breaks. Cheers Sean

Nothing more reassuring than having your monitors green light flashing away.
Friday... laid mat and set about glueing it down, customer walks in, 'Can I walk on it' Er no, 'Well how do I get out the back door then', Er you use the front!! customers!!!

 

[pjrich]

I have searched high and low for instructions on how to test resistance on my Uheat UFH mat.
I bought the mats & multimeter from Uheat, but not too sure on how to use it. I set the multimeter dial to 200 ohms and plugged the leads into the COM and VΩmA holes. The other ends of the leads were touching on the live and neutral leads of the mat. I got 2 different readings from the 2 different sized mats. Reading one (small mat) was 41.1 and the other (large mat) was 31.4. Does this sound right?</SPAN>
Everyone is saying that laying the mats is easy, but this is my first time. I also bought the monitor, which will alarm if the cable breaks. Cheers Sean

Sean,

Just checked what we supplied and the 41.1 Ohms for the 8m2 and 31.4 Ohms for the 10m2 are absolutley perfect.

If you need any advice please give us a call on 01394 384077

 

[siremastimus]

Sorry I know this is a really old thread but I am about to install my first ufh mat bought from uheat along with their multimeter and found this thread helpful! I measured the heating wire resisantce and it was pretty much spot on 110 which looks to be correct for this mat (MG-MD 3.00), what I am a bit confused on is in the instructions it also says to measure the insulations resistance by connecting red to brown and black to yellow/green I think but I get no reading on this and the device used (a megaohmmeter) to measure this looks to be different than the one used to take the previous reading which is the digital multimeter as below:

Underfloor Heating | Installation Accessories | Uheat

Can / do I need to measure the insulation resistance with the above device and if so how? It says it must be below 10 and is also referenced in their online videos

Many thanks