Name: Resideo AT175F1023/U General Purpose Transformer with Manual Reset
Brand: Resideo
SKU: HONE-AT175F1023/U
Price: 98.74 USD
Availability: InStock

General Purpose Transformer with Manual Reset

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Frequency	60 Hz
Electrical Ratings	Primary voltage--120 Vac, 208 Vac, 240 Vac; Secondary voltage--27.5 V.O.C.
Mounting	Includes 1/2 14 NPSM conduit connector and lock nut for mounting on plate or panel (not included) with 7/8 in. knockout, and feet for surface mount.
Includes	Button for manually resetting the circuit breaker and metal end bells.
Dimensions	3 3/16 in. high x 2 3/16 in. wide x 3 15/16 in. deep
UL	UL Listed: A,C,F models. File # E14881
CSA	CSA Certified: A & B models.
Temperature Range (F)	-20 F to +105 F
Electrical Connections (Primary)(in.)	9 in leadwires
Electrical Connections (Secondary)(in.)	9 in. leadwires
Electrical Ratings, Output	24 Vac at 75 VA

Installation Instructions for AT150F, AT175F Universal Circuit Breaker Transformers PDF ↗
Maintenance/Product Reference Materials-Residential Combustion Application Selection and C PDF ↗

The AT175F1023 is a control transformer from Resideo (Honeywell Home), 175 VA.

Almost every heating and cooling control runs on 24 volts, and the transformer is what makes it. It takes line voltage in and delivers the low-voltage supply that the thermostat, the zone valves, the relays and the gas valve all share.

Size it by VA, not by voltage. VA is the load the transformer can carry, and every device on the control circuit adds to it — a zone valve pulls current while it drives, a relay coil holds current the whole time it is energized, and a Wi-Fi thermostat draws continuously. A transformer sized for the original equipment will not carry the same system after two zones and a smart stat have been added, and the symptom is intermittent: things work alone and fail together.

This model has a manual reset: an overload opens the transformer and it stays open until someone presses the button. That is deliberate. A self-resetting transformer that keeps cycling on a shorted control wire hides the fault; one that stays off makes you find it.

Brand: Resideo (Honeywell Home)
Manufacturer Part #: AT175F1023/U
Type: Control transformer
Rating: 175 VA
Secondary: 24 Vac
Reset: Manual
Shipping weight: 2.8 lb
Category: Transformers

Full Specifications

NEMA Rating	No
Primary Connection Size	9 in, 229 mm
Primary Input Voltage	120/208/240 V ac
Secondary Connection Size	9 in, 229 mm
Secondary Connection Type	Leadwires
Secondary Open Circuit Voltage	27 V.O.C.
VA Rating	75 VA
Frequency	60 Hz
Approvals and Standards	UL Listed: File no. E14881, Guide no. XOKV, CSA Certified: File No. LR95329-18
Includes	1/2-14 NPSM conduit connector, Lock Nut, Mounting Feet
Color	Metallic
Ambient Operating Temperature (Max)	105 °F, 41 °C
Ambient Operating Temperature (Min)	-20 °F, -29 °C
Product Height	3.19 in
Product Length	2.19 in
Product Width	3.94 in