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Direct or Relay: How to Wire In-floor Heat to the Thermostat

Direct or Relay: How to Wire In-floor Heat to the Thermostat


We frequently receive emails and calls from customers wanting our recommendation on wiring Gold Heat radiant floor heat mats and film to the provided thermostat. While each thermostat includes wiring instructions, we know each project is unique and it is better safe than sorry.

If you are curious to know how easy the wiring of the Gold Heat In-floor Heat System is, or need a refresher, here are notes from our engineering department. If you have questions, or need help with your specific project, PLEASE, call us (503-848-6190) or email (

For the most basic installation (1-2 mats) directly wired to the thermostat:

  • The line side terminals are attached to the wires coming from the dedicated floor heat beaker to the hot and neutral terminals on the back of the thermostat.
  • The load side terminals get the black and white wires from the cold lead attached to them. If wiring two mats, wire both white cold lead wires on one terminal and both black to the other.
  • All ground wires are tied together. The ground wires on the cold lead are the two tined copper wires indicated by the green heat shrink band.
  • Then wire the floor sensor wire to the two small terminals on the front of the thermostat base unit (under the face plate, visible when the face plate is removed). These sensor wires are non-polar.
  • If a backup sensor wire was installed, label it in the box, but do not connect it. Only one sensor at a time should be connected to the thermostat.

For more than two mats:

  • Same installation as above, but rather than wiring the mats directly to the thermostat, use an appropriately sized run of wire from the load terminals on the thermostat to a junction box. Then all the appropriate mats are wired together in parallel and wired to this run going to the thermostat.
  • NOTE: the sum of the amperage indicated on the tag of the mats should not exceed the rating of the thermostat.

For multiple mats using relays:

  • The wiring is the same as connecting a thermostat, except the sensor wire, which is not used on the relays.
  • Connect the relay to the control terminals under the faceplate on the main thermostat. Note, depending on the thermostat the order of the connections may be specific. See the thermostat and relay instructions for details on your particular equipment. Wireless relays will not need to do this step, but will need to follow the pairing instructions in the instructions for that particular model.
  • If only two mats are connected to the relay, no additional junction box is needed. If more than two are attached, use the same method as an installation, “For more than two mats,” regarding connecting the mats to the relay.

Follow the instruction manual on pairing the relays to the appropriate thermostat. Please use the break out of the mats and zones for planning what gets wired to which device. We also recommend labeling each thermostat/relay appropriately.

Also, cold leads on Gold Heat radiant floor heat mats can NOT be shortened. If there is access, it should be coiled up in a dead space or in a junction box. If the cold lead is shortened, it may make it impossible for diagnostics to be done on this mat in the future. Black Gold cold leads, however, can be shortened if needed.

If you have any questions or need additional help, please contact us.