Tempstar 40VA Transformer for T8MPV050B12C1 — 115V to 24V Control Transformer | Ships Today

Overview

This OEM 40VA control transformer (part number 1172810, "TRANS 115>24 40VA") provides the low-voltage control power for the Tempstar T8MPV050B12C1 gas furnace. It steps 115V line voltage down to 24V to operate the thermostat, gas valve, board relays, and other control-circuit components, with a 40VA rating to handle these loads together. When the transformer fails — from a shorted secondary, an overloaded control circuit, or age — the furnace loses all 24V power: the thermostat goes blank and the system stops responding to heating or cooling calls.

Specifications

Compatibility

Direct-fit replacement for the Tempstar T8MPV050B12C1 furnace. This 115V-to-24V 40VA transformer is a common ICP service part used across many Tempstar, Heil, and Comfortmaker furnaces and air handlers. Confirm your primary voltage and VA rating before ordering.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker. Verify zero voltage with a multimeter.
2. Access — Remove the control/blower service panel to reach the transformer.
3. Document — Photograph all primary (line) and secondary (24V) connections before disconnecting.
4. Remove — Disconnect the leads, remove the mounting hardware, and lift out the failed transformer.
5. Install — Mount the new transformer and reconnect the primary and secondary leads exactly per your photo.
6. Test — Restore power and confirm 24V at the secondary and normal thermostat/furnace operation.

Signs You Need a Replacement

• Thermostat is blank and the system is completely unresponsive.
• No 24V measured across the transformer secondary.
• Repeated blown low-voltage control fuse.
• Burnt smell or discoloration on the transformer body.

Shipping & Returns

Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.