Tempstar 40VA Transformer for T8MPL050B12B2 — 115V to 24V | Ships Today
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Overview
This OEM 40VA control transformer (part #1172810) steps down 115-volt line power to the 24-volt low-voltage control circuit that runs your Tempstar T8MPL050B12B2 furnace. Every call for heat — from the thermostat to the gas valve, igniter, and blower relays — depends on clean, stable 24VAC supplied by this transformer. When it fails, the entire control board goes dark: no thermostat response, no ignition sequence, and no blower. A 40VA rating provides the amperage headroom needed to energize multiple relays and the gas valve simultaneously without overheating. Common failure signs include a dead thermostat display, a furnace that won't start, a buzzing transformer, or a blown low-voltage fuse on the control board caused by a shorted secondary.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1172810 |
| Type | Control Transformer |
| Brand | Tempstar (ICP / Heil) |
| Rating | 40 VA |
| Primary Voltage | 115 VAC |
| Secondary Voltage | 24 VAC |
| Fit | OEM Direct Replacement |
Compatibility
Designed as a direct-fit replacement for the Tempstar T8MPL050B12B2 gas furnace and shared across many ICP-family platforms (Tempstar, Heil, Comfortmaker, Arcoaire) using the 1172810 transformer. Always confirm your existing transformer is rated 115V/24V at 40VA before installing.
Installation Guide
- Safety First — Disconnect power at the furnace switch and breaker, then verify zero voltage with a multimeter.
- Access — Remove the furnace service panel to expose the control area.
- Document — Photograph all primary (line) and secondary (24V) wire connections before disconnecting.
- Remove — Disconnect the line and low-voltage leads, then unbolt the failed transformer from its mounting bracket.
- Install — Mount the new transformer, reconnect 115V to the primary and 24V to the secondary exactly per your photo.
- Test — Restore power, confirm 24VAC at the secondary, and run a full heat cycle.
Signs You Need a Replacement
- Blank or unresponsive thermostat with confirmed line power present
- No ignition sequence — gas valve and igniter never energize
- Audible buzzing or humming from the transformer
- Repeatedly blown low-voltage control fuse
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