Resideo - Honeywell Home AT40A1121 Standard Universal Stripped-Down Transformer

The AT40A1121 transformer delivers reliable power for residential combustion control systems. The AT40A1121 transformer features a 120 VAC primary and a 24 VAC secondary to support standard Honeywell/Resideo configurations. This standard universal stripped-down transformer provides robust compatibility while maintaining a compact footprint for tight installations.

Designed as a stripped-down, universal unit, it handles 50/60 Hz frequency, 40 VA of power, and a temperature rise from -20 to 105°F, all within a NEMA Type D enclosure. The unit's compact dimensions are 2-5/8" W x 2-3/16" D x 2-3/32" H and it includes a mounting foot for straightforward mounting in residential control panels.

Applications are ideal for residential combustion control systems, and the transformer is UL and CSA approved for dependable safety and compliance. The package includes the thermostat, gas valve, and relay to streamline installation and reduce accessory sourcing.

• Primary Voltage: 120 VAC
• Secondary Voltage: 24 VAC
• Power Rating: 40 VA
• Frequency: 50/60 Hz
• Enclosure: NEMA Type D
• Dimensions: 2-5/8" W x 2-3/16" D x 2-3/32" H
• Mounting: Mounting foot
• Applications: Residential combustion control system
• Approvals: UL, CSA
• Includes: Thermostat, gas valve, relay