Wiring Scenarios for MRCOOL Central Ducted Hyper Heat System

This guide outlines three common wiring setups for your MRCOOL Central Ducted Hyper Heat system, ensuring proper communication and functionality between the air handler, condenser, and thermostat.

1. Default 2-Wire Communication Setup

• Condenser to Air Handler: Connect to S1/S2 terminals. Tip: Make sure you are connecting to the proper terminals as there are 2 different plastic terminal covers, one of which is R/C.
• Air Handler to Thermostat: Use HA/HB terminals.
• This setup is specifically designed for the thermostat included with the MRCOOL kit.

This simple configuration ensures smooth operation.

2. 24V Thermostat Wiring Setup

• Condenser to Air Handler: Connect via S1/S2.
• Air Handler to Thermostat: Use 7 wires (R, B, C, G, Y1, Y2, W). W is only needed if using heat strips. Y1 or Y2 will not be needed if you do not need to stage the system.
• Settings: Adjust dip switches (SW1-1) to on at the air handler. Set the thermostat as a staged heat pump or non staged based on your wiring. Also, set the reversing valve to energize in heat mode as the default is cooling mode.
• Terminal Designations for 7-Wire Setup:
  • R: 24V power
  • B: Reversing valve (heat active)
  • C: Common
  • G: Indoor blower motor
  • Y1: 1st stage compressor
  • Y2/Y: 2nd stage compressor
  • W: Auxiliary heat

This configuration provides the most flexibility.

3. Full 24V Wiring Setup

• Thermostat to Air Handler: 7-wire setup (same as Scenario 2).
• Air Handler to Condenser: Use 24V terminals instead of S1/S2.
• Settings: Set dip switches (SW1-1, SW1-4) to on at the air handler, and dip switch 2 to on at the condenser.

This configuration provides the most control over operation.

Conclusion

Choose a setup based on your thermostat preference. Ensure proper terminal connections and dip switch settings for optimal performance. If unsure, consult a professional.