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Aprilaire 3-Wire to 4-Wire Adaptor

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SKU: RP8022

WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov

No Extra Wire Needed

Combine any two thermostat equipment terminals (not 24V hot or common) using the Aprilaire 3-Wire to 4-Wire Adaptor. The adaptor includes a diode pair that connects the two terminals and relays their signals through one wire to the adaptor’s circuit board. This eliminates the need for an extra wire.

Possible Applications:

  • Bypassing a broken wire inside the wall
  • Adding an extra heating/cooling stage
  • Upgrading a mechanical or battery-operated thermostat to a 24 volt or power stealing Aprilaire Electronic Thermostat

The circuit board of the Aprilaire 3-Wire to 4-Wire Adaptor mounts inside of your equipment where other control components are located, and the diode pair mounts to the thermostat.


  • Circuit Board
  • Diode Pair
  • Wire Nut

Note: Requires #8 sheet metal screws (not included).

Aprilaire: Feel Good, Inside

It is the mission of Aprilaire to provide superior Indoor Air Quality products for new and existing homes and businesses. Aprilaire products are built to provide you and your family with the most comfortable home and the cleanest, healthiest air possible. Protect your home and your most valuable possession – your family.

  • Voltage: 24VAC Class 2
  • Current: 3.2A
  • Dimensions: 2-3/8(H) x 3-7/8(W) x 1-1/4(D) inches
  • Warranty: 1 Year Limited