How to Wire a Marley MD26 Line Voltage Thermostat

Dylan Kennedy

Installing a Marley MD26 Line Voltage Thermostat could save you hundreds of dollars a year in home heating and cooling costs. If you have an older model currently installed, then you remove and replace with a newer thermostat. The line voltage device hooks straight into the power system, rather than having a transformer in between to cut down the voltage for low voltage systems.

Basic electrical and wiring knowledge helps when installing a new thermostat.
  1. Shut off power to your old device. Go to the circuit breaker in the house and flip it off for this area.

  2. Remove the old thermostat from the wall. Unscrew each corner and take it down. Notice the placement of the electrical wires if its a similar model.

  3. Hook the wires into the back of the Marley MD26. Connect each wire to the proper terminal and tighten them down. R goes to Red, G goes to Green, Y goes to Yellow and W goes to White.

  4. Fasten the thermostat to the wall by drilling the screws in. Each corner should hold the device flat against the wall.

  5. Turn the power back on through the circuit breaker. Program the Marley once it powers on.