THM5421C-1008 | Honeywell RedLINK equipment interface module for multi-stage HVAC systems

Honeywell · HMIs & Displays

Description  The Honeywell THM5421C-1008 is an equipment interface module that enables communication between HVAC equipment and RedLINK-enabled thermostats. This module provides centralized control of heating, cooling, and indoor air quality functions using a simplified three-wire connection to the thermostat. Designed for compatibility with VisionPRO IAQ systems, it supports multi-stage conventional and heat pump applications.   Technical Specifications  Condition New/Never Used Surplus Brand Honeywell Category Controls & Indicators Part Number THM5421C-1008 Subcategory Conversion Module Application Heat/Cool or Heat Pump with Auxiliary Heat Used With TH9421 VisionPRO IAQ Thermostat Mounting Vertical Power Method Hardwired Supply Voltage 20–30 VAC Electrical Rating THM5421 rated 20–30 VAC Frequency 50/60 Hz Stages Supported Up to 4 Heat/2 Cool (Heat Pump); Up to 3 Heat/2 Cool (Conventional) Dimensions (in.) 7 1/4 H × 4 1/2 W × 1 3/8 D Dimensions (mm.) 185 H × 116 W × 34 D Operating Humidity 5–90% RH, non-condensing Operating Temperature Not specified Fan Current 0.6 A running Heat Current 1.0 A running Cool Current 1.0 A running Color White Included Equipment Interface Module Only   Information About THM5421C-1008 The THM5421C-1008 is part of Honeywell’s VisionPRO IAQ family, serving as the communication bridge between HVAC components and advanced RedLINK thermostats. Its enclosure is designed for vertical mounting and houses terminal connections that streamline system wiring while maintaining organized equipment integration. The module is fully compatible with the TH9421 VisionPRO IAQ thermostat and EnviraZONE systems, enabling unified management of temperature, ventilation, humidification, and dehumidification. Typical applications include residential and light commercial HVAC installations requiring multi-stage control and enhanced indoor air quality management through RedLINK wireless technology. Key Features: RedLINK communication interface: Connects HVAC equipment to RedLINK-enabled thermostats for advanced system control. Supports multi-stage HVAC systems: Handles up to 4 heat/2 cool heat pump or 3 heat/2 cool conventional systems. Integrated IAQ control: Provides centralized management of humidification, dehumidification, and ventilation. Simplified wiring: Uses only three wires to the thermostat for easy equipment upgrades. Wide operating compatibility: Works with 20–30 VAC systems at 50/60 Hz. Compact vertical-mount housing: Fits cleanly into mechanical rooms or HVAC enclosures. High humidity tolerance: Rated for environments up to 90% RH, non-condensing. The THM5421C-1008 delivers the reliability and precision required for advanced HVAC equipment interface and indoor air quality control.

Brand: Honeywell · Category: HMIs & Displays

Key features

• RedLINK communication interface: Connects HVAC equipment to RedLINK-enabled thermostats for advanced system control.
• Supports multi-stage HVAC systems: Handles up to 4 heat/2 cool heat pump or 3 heat/2 cool conventional systems.
• Integrated IAQ control: Provides centralized management of humidification, dehumidification, and ventilation.
• Simplified wiring: Uses only three wires to the thermostat for easy equipment upgrades.
• Wide operating compatibility: Works with 20–30 VAC systems at 50/60 Hz.
• Compact vertical-mount housing: Fits cleanly into mechanical rooms or HVAC enclosures.
• High humidity tolerance: Rated for environments up to 90% RH, non-condensing.

Specifications

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