Foil Heating System – FOIL

Check the resistance readings of your heating wires

To ensure that your floor heating system will function properly, always test the resistance of your wires with a digital multi-meter before, during and after installation prior to covering in thin-set or floor leveler.


Use the information contained on page 6 of the installation manual for details. If at any point during one of your tests the results do not match up with the numbers your Warmup manual indicates you should have, you may have a short or a break in your wires.


Warmup can provide your installer with the tools needed to perform a repair when possible.


If you purchased a Digital Multi-meter from Warmup you will have 2 connectors as shown below. Please make sure that the contacts that will be plugged into the multi-meter are properly exposed as illustrated below.  It is possible that you may have to remove some of the sheathing from the connector ends to expose them enough to make the needed contact with the multi-meter in order to receive accurate readings.


 Multimeter connectors


Note as illustrated below that the red connector is plugged into the outlet labeled “VΩmA” and the black connector into the “COM” outlet.  The dial should be turned so that the indicator points to the 6 o’clock position, directly above the “200Ω” indicator.




IMPORTANT NOTE:  The testing outlined below must be performed before connecting the heating system to a power source or only after disconnecting if already installed.


1.  You will take your readings 3 times. Once you first remove your heating system from the box, mid-way through the laying out of the floor heating system and right before you connect the floor heating system to the thermostat.  


2.  Clip the alligator head of the black connector to the black wire of your heating system and the alligator head of the red connector to the yellow wire. This is your “core to core” reading. Compare the ohm number that appears on the display to what the installation manual says it should be for the model floor heating system you purchased. Note: +/- 10% of the norm is acceptable.


3.  Next clip the alligator head of the black connector to the black wire of the floor heating system and the alligator head of the red connector to the yellow/green wire (neutral).  You want to see the number “1” or if using another brand of digital multi-meter it will be the “infinity symbol – ∞.”  Now you will leave the red wire connected to the yellow/green wire but this time clip the black connector to the yellow wire of the floor heating system.  Again, you want to see the number “1” or the infinity symbol.


If your results deviate in any way from the results indicated above call Warmup immediately for further instructions.