2.9: In-Floor Heating

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Page ID: 18032

Aaron Lee
BC Campus

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15 In-Floor Heating

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A BCcampus element has been excluded from this version of the text. You can view it online here: https://opentextbc.ca/basichvac/?p=61

As anyone who has walked on a cold tiled floor in their bare feet can attest, nobody likes cold toes. Likewise, anyone who has shovelled snow off their driveway or sidewalk will agree that not dealing with snow would be far superior. The good news is that in-floor heating exists to help ameliorate these situations.

By installing resistive heating cables below the finished floor, such a tiled floor in a bathroom, we can eliminate the heat sapping characteristics of the cold tiles, however underfloor heating sets are not intended to be a source of heat for the room.

Heating cables can also be installed below driveways and walkways for the purpose of melting ice or snow in the winter. When laid in concrete, cables must be of a material that is resistant to any chemical reaction.

This is a similar process to installing heat trace cables for freeze protection on plumbing, and drain piping.

Some manufactures produce heating cables that are embedded in mats which are laid out below the tiled floor to be installed, in which case cable spacing is not a problem. If the heating cable comes on a roll, the cable is usually installed at a spacing of about 150 mm to 300 mm. Regardless of the style, they are commonly designed for a loading between 40 and 160 watts per square meter.

One of the most important details to keep in mind is to never shorten the length of cable when installing in the field. Doing so would change the series connected resistance of the cable, and thus change the current drawn and the power dissipated by the cable, perhaps beyond safe conditions.

The system can be controlled by a wall mounted thermostat that has a remote sensor embedded in the floor to sense floor temperature.