The quick answer is no. But let us explain why.
The heating element inside each individual mat and cable is designed to produce a set amount of heat: 12–15 watts/sq ft or 41–51 BTUs (the measure of energy). Shortening the length of a heating element will cause it to produce more than the set amount of heat. Doing so can:
- Decrease the life-span of the system
- Void the warranty
- Cause the system to fail compliance (based on the North American electrical code)
We’ll review the basics of electricity to help explain why a heating element can’t be shortened.
Basic units of electricity:
- Voltage (V)
- Measured in volts and identifies electrical power
- Current (I)
- Measured in amps
- Resistance (R)
- Measured in ohms (Ω)
- Power (P)
- Measured in watts
To better understand these terms, think of plumbing pipes. The voltage (V) is equivalent to water pressure, the current (I) is equivalent to the flow rate of the water, and the resistance (R or Ω) is like the pipe size.
Another way to think of this is to imagine pointing a water hose at a waterwheel. You can increase the power (P or watts) generated by the waterwheel in two ways.
- If you increase the pressure of the water coming out of the hose (V or volts), it hits the waterwheel with a lot more force and the wheel turns faster, generating more power.
- If you increase the flow rate (current or amps), the waterwheel turns faster because of the weight of the extra water hitting it.
How does this relate to electric radiant floor heating? Electric radiant floor heating systems use “resistant heating” elements. The key to understanding this is knowing each mat and cable is made with a specific resistance or number of ohms.
At the beginning of this article we stated that each mat and cable is designed to produce 12–15 watts/sq ft or 41–51 BTUs. Applying the basics of electricity, we know that the specific amount of heat means we have a required amount of resistance. Producing the correct amount of heat for your floor depends on the amount of resistance and voltage working together. By shortening or extending the heating element, you are changing the amount of resistance.
Heating a floor is different from the heating of air because the floor absorbs and holds the heat in place, while air being heated in a room moves and spreads.
Remember: Hot air (not heat!) rises, but your floor stays in one place as it heats up and creates a thermal mass (think of a hot pan on a stovetop).
If the resistance of the heating elements in your floor could be dialed up or down like the ones in a space heater or an electric stove, it could become too hot or heat up too quickly.
Our manufacturers create each mat and cable with a specific resistance to ensure your heated floor will be comfortable, efficient and above all safe. Shortening or lengthening the heating elements will compromise the carefully built and tested designs.
Fields Misselwitz says:
I have made a mistake. I have installed better than 400 square feet of tile floor over self leveling concrete and radiant heat. I have only a small section left to do and I am going to have about 25 feet of extra wire. Is there anything that I can do short of tearing out the whole floor?
[email protected] says:
Hi Fields,
Without knowing which brand you’re using, you should check the manual for the product and see if the manufacturer says you can space the cable closer than you have been.
Most manufacturers allow for closer spacing which could help you use the extra cable appropriately.
Other options would be to install the cable in an area you weren’t going to heat but could.
Depending on how far from the walls you stayed, you may be able to just run a single strip of cable along the edge of the room as well.
LOUIS PAKULA says:
we are are doing a remodel and wanted to see if it is possible splice the wirers to the termastat so it can moved a little farther away .
Marye Lee says:
Hi Louis,
Although the heating cables cannot be cut, the power leads for the thermostat can be spliced. We recommend that the splice be contained within an electrical box and then proceed to extend it to the thermostat location. Please, give us a call at 866-558-3369 if you have further questions on how to splice the power lead.
Warm Regards,
Warm Your Floor Team
tim moore says:
can i extend my lead wires with 14 gauge insulated wire and also use solid ground for the ground connection extension?
[email protected]
[email protected] says:
Hi Tim,
The lead wires are 18 gauge so a 14 gauge wire and the solid ground should be sufficient to extend the lead wires.