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Smart Wi-Fi Thermostat - MTS300 Compatibility Check
This smart thermostat is compatible with most low-voltage(24V~) HVAC systems, including single or multi-stage heating and cooling systems, heat pumps(with or without AUX heating), and fan coil units. It supports up to 2-stage cooling, 3-stage heating, 2-stage heat pump, 3-speed fan, and a humidifier or dehumidifier. The terminal definitions is shown below, you can also use the compatibility checker to check.
TerminalsConventionalHeat Pump2-Pipe Fan Coil4-Pipe Fan Coil
R24V~ Single Transformer - Heating or Cooling
Rc24V~ Dual Transformer - Cooling
Rh24V~ Dual Transformer - Heating
CCommon
GFan
YStage-1 CoolStage-1 CompressorValveCool Valve
Y2Stage-2 Cool (2nd-speed Fan)Stage-2 Compressor (2nd-speed Fan)2nd-speed Fan2nd-speed Fan
W/AUXStage-1 Heatstage-1 AUX HeatAUX HeatHeat Valve
W2Stage-2 Heat (3rd-speed Fan)stage-2 AUX Heat(3rd-speed Fan)3rd-speed Fan3rd-speed Fan
O/BN/AReversing ValveN/AN/A
EN/AEmergency HeatEmergency HeatN/A
*Humidifier/Dehumidifier/W3/AUX3

Note:

1. This thermostat supports a 1-wire humidifier/dehumidifier or 2-wire humidifier/dehumidifier. If installing a 1-wire humidifier or dehumidifier, connect it directly to the * terminal. For a 2-wire unit, an additional 24VAC relay is required. We recommend using the 90-290Q model or a similar relay.