Tips and Wiring options for Under floor (Under tile heating for larger areas)

If you are floor heating larger areas such as living, dining and lounge areas etc, it is important to plan in advance. By using series of smaller mats to make up the larger area, it is easy to create zones for the ultimate in control and comfort. You may have one controller controlling the whole area, or several controllers for different zones, its up to you and your imagination!

The best way to control large floor heated areas

There are a few ways this can be done.

The traditional method is to run the feeds from the heating mats back to the switch board and have a series of relays (located at the board) triggered by the controller/s. The main reason the relays are located back at the board is due to the noise the relays make while switching. Electromechanical relays or contactors are too noisey to locate within the house. You don’t want loud “clunks” scaring you in the middle of the night! This method is “old school” and outdated in the floor heating industry. However, I see many new installations like this as electricians are generally used to roughing in the wiring this way. With this method there is also a lot of extra wiring required as the relays are located at the switchboard and the controllers are located within the home, so the wiring really is going back and forth!

Solid state relays and floor heating

With our quiet switching solid state relays, you can control any large floor heated areas from just a single controller or run several controllers for separate zones. Due to our quiet switching solid state (no moving parts) relays, they can be located just behind the controller and generally just “hang” behind the controller. Our solid state relays are roughly the size of a matchbox.

They are small, quiet and awesome!

Why you need to use relays when heating larger floor areas

Modern floor heating controllers are really quite amazing! They are thermostats, relays and timers all built into one. The controllers on-board relay is a solid state relay, and generally will be rated to handle up to approximately 16 amps. Different controllers may have different power handling capabilities, so this must be checked first. If you have a larger electrical load for the area you want to control than the controllers rating, you can use an external relay which is triggered by the controllers on-board relay output. Some larger floor heated areas may require several external solid state relays triggered by the one controller. It`s all a matter of balancing the electrical load, and not having any one component working too hard.

All cold tails go back to the controller location

It is very important to bring all cold tails up to a connection point when laying a large area heated floors . There are a few reasons for this.
  1. Most electricians avoid making connections in the floor as you can`t get to that connection if it fails in the future.
  2. If you bring all heating element cold tails up to the controller point or another connection point that will loop back to the controller, you can separate a single heating cable from all others in case of damage.
  3. If you have all heating mat cold tails available at the controller location, you can balance the electrical load more accurately between the relays.
If you join larger heated flooring mats together before the controller, the electrical load may be over the rating of the relay.

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