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How to Check the Resistance Readings of your Electric Floor Heating System

Heating Mats – DWM

To ensure that your floor heating system will function properly, always test the resistance of your wires with a digital multimeter set to 200 ohms before, during and after installation.

Warmup heating cables are constant wattage cables that should be tested on a 200-ohm scale. Always ensure resistance matches the information on the product tag/box. Each heater model has it’s own unique resistance reading. If at any point during one of your tests the resistance results do not match up, call Warmup.

It is very important that you record the heater model number, final core to core resistance readings, and final resistance readings each leg to ground. These records are what you will use to register your warranty.

Warmup Tip: Remove the tag from the cold tail lead of the product and tape it inside of your electrical panel for future reference.

For a record card and more information on testing refer to the installation manual. If you are in need of a multimeter you can order a Warmup Alligator here.

If you purchased a Digital Multimeter from Warmup, the Alligator,  you will have two connectors.  Please make sure that the contacts that will be plugged into the multimeter are properly exposed.

Connect the red clip into the outlet labeled “VΩmA” and the black connector into the “COM” outlet.  Turn the dial so that the indicator points to the 6 o’clock position, directly above the “200Ω” indicator.

Testing Resistance for 120V/240V Systems

IMPORTANT NOTE:  Perform the testing below 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
  • 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. The connect 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 tag, box or installation manual state the reading should be for the model you purchased.  Note: +/- 5% 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 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.

Watch the below video and follow along as a system is tested. Subscribe to our YouTube channel for more Warmup videos!

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Further Questions?