Honeywell THM5421R1021, Equipment Interface Module (EIM) for all Prestige IAQ and new RedLINK VisionPRO Thermostats (Replacement for THM5421R1005, THM5421R1013)

SKU / MPN: THM5421R1021

$107.48 $168.64

In Stock - Ships in 1-2 business days



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Product Information


The Honeywell Home THM5421R1021 Equipment Interface Module (EIM) is a small, easy-to-install device that connects your Prestige IAQ or new RedLINK VisionPRO thermostat to your HVAC system. Experience precise temperature control for enhanced comfort while optimizing your HVAC system's operation to save energy. In addition, gain peace of mind with remote access to your thermostat, allowing you to monitor and adjust your home's temperature even when you're away. The EIM is fully compatible with all Prestige IAQ and new RedLINK VisionPRO thermostats, directly replacing the THM5421R1005 and THM5421R1013 models.ÂÂ


  • Connects your Prestige IAQ or new RedLINK VisionPRO thermostat to your HVAC system
  • With a Heat Pump System: Controls up to 4-stages of heatÂÂ 2-stages of cool in a heat pump system
  • With a Conventional System: ControlsÂÂ up to 3-stages of heat and 2-stages of cool
  • Three sets of Universal IAQ contacts to control humidification, dehumidification, and ventilation
  • Four sensor inputs for wired sensors or dry contact devices
  • Provides improved comfort and energy savings
  • Remote access to your thermostat
  • Compatible with all Prestige IAQ and new RedLINK VisionPRO thermostats
  • Direct replacement for the THM5421R1005 and THM5421R1013 models


  • Application: Heating & Cooling
  • Stages:ÂÂ 4 Heat/2 Cool Heat Pump &ÂÂ 3 Heat/2 Cool
  • Operating Tempeture: -40 to 165 deg F operating temperature
  • 5-95 percentage RH, non-condensing operating humidity
  • Voltage: 24v
  • 18-30 VAC
  • 50/60 Hz
  • Dimensions:ÂÂ 9-5/16 inch height x 4-13/16 inch Width x 1-5/8 inch D
  • Terminal: Screw bound
  • Color: Gray
  • Weight Approximation: 1 lb

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Safety Information: Proposition 65

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