Honeywell AT175F1023 Transformer

The Honeywell AT175F1023 (also known as AT175F1023/U) is a heavy-duty, 75VA general-purpose control transformer designed to meet the rigorous demands of multi-tap HVACR applications. Engineered for maximum field flexibility, this step-down transformer features a primary voltage range of 120V, 208V, and 240V, making it a universal solution for powering 24V secondary control circuits in residential and commercial heating or cooling systems. Built to UL 1585 standards, it is rated as a Class 2 energy-limiting transformer, providing reliable power for thermostats, gas valves, and relays without exceeding load ratings.

For technicians in the field, the AT175F1023 simplifies installation with its versatile foot mounted and hub-mount design, including a 1/2-14 NPSM conduit connector. Unlike standard models, this unit includes an integrated, manually resettable circuit breaker to protect the secondary winding from overloads and shorts, eliminating the need for external fusing. The 9-inch color-coded lead wires allow for rapid identification and secure NEC Class 2 compliant wiring in tight electrical cabinets.

Key Benefits for the Contractor

• Universal Multi-Tap Primary: Supports 120/208/240 VAC inputs, reducing the number of truck-stock SKUs required for service calls.
• Integrated Circuit Breaker: Features a manual reset button to protect internal windings from field wiring shorts or over-current conditions.
• High Power Capacity: 75VA rating provides ample overhead for complex control strings and multiple 24V accessories.
• Flexible Mounting: Equipped with dual-mounting options, including feet for surface attachment and a 1/2" NPT hub for junction box knockouts.
• Code Compliance: Meets UL 1585 requirements and is identified as Class 2 "not wet" for professional-grade installations.

Common Technician Questions What is the difference between the AT175F1023 and the AT175F1023/U? There is no functional difference; the "/U" suffix simply denotes the retail/universal packaging. They are 100% identical and interchangeable in all technical specifications. How do I reset the transformer if the secondary circuit shorts out? Locate the white reset button on the side of the metal end bell. Ensure the short is cleared and allow the transformer to cool if necessary before pressing the button to restore the 24V output. Can this transformer be used for smart thermostats with high power draws? Yes, the 75VA rating is specifically designed to handle the higher current demands of modern Wi-Fi thermostats and multiple zone valve actuators that standard 40VA transformers cannot support.

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.