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The Honeywell ERM is like a new cordless tool in your toolbox. Pull it out whenever it's too costly or time-consuming to run wires from a condensing unit or boiler to control devices. There are fewer holes to drill and wires to run. Just faster, easier installation that gives you more profit per job. Make the Honeywell ERM your go-to choice for fast, easy equipment installation.


  • Wireless RedLink™ communication between condensing unit/compressor or boiler and thermostat.
  • Eliminates the need to run additional wires to your equipment, for example, during a heat pump upgrade.
  • Suitable for outdoor use.
  • Temperature sensor terminals for outdoor temp sensors or indoor freeze protection.
  • LEDs for easy installation checkout.
  • May reduce damage to homes since wiring/drilling is eliminated.

Product Specifications

Wireless RedLink™ communication between condensing unit/compressor or boiler and thermostat.
Dimensions (in.)
6-78 in. wide x 6-39/64 in. high x 1-31/64 in. deep
Dimensions (mm)
175 mm wide x 168 mm high x 38 mm deep
Item Type
Attach the ERM to the wall near the compressor or bolier. The location should be at least 3 feet above ground and oriented with the two wire exits facing downward.
Electrical Ratings
24 Vac, 50Hz; 60 Hz
Up to 2 Heat / 2 Cool Heat Pump or Up to 2 Stage Conventional
Operating Humidity Range (% RH)
0 to 99% RH
Approvals, Federal Communications Commission
Complies with FCC Part 15a
Compressor; Bolier; Connected
Ambient Temperature Range (F)
Compressor: -40 F to +155 F; Boiler: 30 F to +130 F
Ambient Temperature Range (C)
Compressor: -40 C to +68 C; Boiler: -1 C to +54 C
Terminal Designations
J, R, C, Y, Y2, O/B, D, L, S1, S1
ERM is not compatible with RedLink Zone boards
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