Fan Center with SPDT Switching Action, 40VAC

Honeywell R8239A1052/U Fan Center – 24V Transformer and SPDT Relay for Low-Voltage HVAC Control

The Honeywell R8239A1052/U is a combination fan center featuring a 24V transformer and a single-pole double-throw (SPDT) relay for low-voltage control of line-voltage fan motors and auxiliary HVAC components. This unit is suitable for use in heating, cooling, or combined system configurations where relay switching and 24V power are required in a single compact assembly.

The transformer is a NEMA Type D 40 VA unit mounted to a compact base with integral relay and accessible wiring terminals. The fan center simplifies system wiring and is intended for indoor installations requiring control of blowers, fans, or other switching applications within HVAC systems.

Product Features

• Relay Type: SPDT relay with replaceable design for serviceability
• Transformer: 40 VA, NEMA Type D, provides 24 VAC output for thermostat circuits
• Mounting: Indoor-rated surface mount in junction box or equipment enclosure
• Wiring Terminals: Clearly marked screw terminals for simplified field connections
• Overload Protection: Internal protection on transformer secures against overcurrent conditions
• Relay Access: Allows relay replacement without disturbing the field wiring

Technical Specifications

• Model: R8239A1052/U
• Control Voltage: 24 VAC
• Primary Voltage: 120 VAC (transformer input)
• Transformer Rating: 40 VA
• Switch Action: SPDT (Single Pole, Double Throw)
• Mounting Dimensions: 4-1/2 in H × 4-3/16 in W × 3-3/32 in D

Installation Considerations

The R8239A1052/U is designed for use in central HVAC systems requiring fan relay control with low-voltage thermostat compatibility. The compact layout fits standard junction boxes or mounting plates. Installation should be performed by licensed HVAC technicians to ensure compliance with electrical codes and manufacturer requirements. Transformer leads and relay contacts should be checked for compatibility with the system load before energizing the circuit.

Application Use

Typical installations include furnace blower control, fan centers in split systems, or as a relay interface between 24V thermostats and line-voltage fans. The unit provides reliable switching performance in both new construction and retrofit scenarios, supporting fast field wiring and maintenance with its accessible layout and modular relay replacement feature.