| 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 |
Description
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