Resideo RC845 Relay

The Resideo RC845 Relay is an essential heat pump add-on relay engineered for integrating modern heat pumps with existing fossil fuel furnaces. Professional contractors rely on this switching relay to manage the handoff between high-efficiency cooling and auxiliary heating sources, such as gas, oil, or electric furnaces. This AddOn Fossil Fuel Relay features a low-voltage dry contact output for triggering auxiliary heat and a dedicated line-voltage output for independent fan control. Its compact design allows for seamless installation directly into or onto a standard 4x4 electrical box. By utilizing the Resideo RC845, you ensure the furnace fan operates correctly during both heat pump and auxiliary cycles, preventing limit trips. The 24V HVAC relay is compatible with most standard heat pump thermostats and includes clearly labeled lead wires to streamline field wiring and reduce diagnostic time. This heavy-duty component supports inductive loads up to 1.0 HP at 208 VAC, making it a rugged solution for residential and light commercial dual-fuel retrofits.

• Dual-Fuel Integration: Enables seamless switching between a heat pump and gas or oil auxiliary heating systems.
• Integrated Fan Control: Features a line-voltage contact to drive the furnace fan independently of the burner circuit.
• Simplified Wiring: Replaces complex two-relay setups with a single, color-coded internal configuration.
• Versatile Mounting: Includes a lock-nut for quick attachment to standard conduit knockouts or internal junction box mounting.
• Wide Compatibility: Works with various 24V thermostats to manage auxiliary heat sequencing efficiently.

Can the RC845 be used with electric furnaces?
Yes, it is designed to control gas, oil, or electric furnaces as the auxiliary heat source when adding a heat pump to the system.

Does this relay handle the blower motor directly?
The relay includes line-voltage contacts rated for fan control, allowing it to bypass the furnace's internal fan logic when the thermostat calls for heat pump operation.

Where should the RC845 be mounted?
It is typically mounted on a 4x4 electrical box or inside the furnace cabinet where low-voltage and line-voltage connections are accessible.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.