Tempstar 40VA Transformer for T9MPV125L20A2 — 115V to 24V | Ships Today
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Overview
This is the genuine OEM 40VA control transformer (part number 1012722) for the Tempstar T9MPV125L20A2 gas furnace. The transformer steps line voltage (115V) down to the 24V low-voltage control circuit that powers the thermostat, control board, gas valve, and ignition system. A 40VA rating provides ample capacity for the furnace's full control load. When a transformer fails, the entire low-voltage circuit goes dead — the furnace will not respond to a thermostat call, the control board may show no power, and you may notice a burnt smell or a tripped/blown low-voltage fuse caused by a short on the 24V side.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1012722 |
| Description | TRANS 115>24 40VA |
| Type | Control Transformer |
| Brand | Tempstar (ICP / Heil) |
| Primary Voltage | 115V |
| Secondary Voltage | 24V |
| Rating | 40 VA |
| Fitment | OEM Replacement |
Compatibility
Engineered as a direct OEM replacement for the Tempstar T9MPV125L20A2 modulating gas furnace. The 1012722 transformer is shared across many ICP-family models (Tempstar, Heil, Comfortmaker, Arcoaire) using the same 115V-to-24V 40VA control platform. Always confirm your existing transformer's part number or VA rating before ordering.
Installation Guide
- Safety First — Disconnect power at the furnace switch and breaker, then verify zero voltage with a multimeter.
- Access — Remove the furnace control/blower access panel.
- Document — Photograph all primary and secondary wire connections before disconnecting.
- Remove — Disconnect the line-voltage primary leads and the 24V secondary leads, then unbolt the failed transformer from its mounting bracket.
- Install — Mount the new transformer, reconnect primary and secondary wiring exactly per your photo, and secure all connections.
- Test — Restore power and confirm 24V across the secondary terminals and normal furnace operation.
Signs You Need a Replacement
- No 24V power — furnace does not respond to thermostat calls.
- Repeatedly blown or tripped low-voltage fuse.
- Buzzing, overheating, or a burnt smell from the transformer.
- Measured secondary voltage is zero or well below 24V.
Shipping & Returns
Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days