Tempstar 40VA Transformer for T8MPL075F16B1 — 115V to 24V Control | Ships Today

Overview

This is the genuine OEM 40VA control transformer (part number 1172810) for the Tempstar T8MPL075F16B1 gas furnace. The transformer steps the incoming 115-volt line voltage down to the 24-volt control voltage that powers the thermostat, gas valve, ignition control board, and safety circuits. Without a healthy transformer, none of the low-voltage controls receive power, so the furnace will not respond to a call for heat at all. Common failure symptoms include a completely dead control board, a thermostat with no display or a blank screen, a blown low-voltage fuse that keeps recurring, or a burnt-electrical smell at the transformer housing. A buzzing or visibly scorched transformer should be replaced immediately.

Specifications

Compatibility

Engineered as the factory replacement for the Tempstar T8MPL075F16B1 furnace and shared across many ICP-family platforms including Tempstar, Heil, Comfortmaker, and other ICP-built gas furnaces using a 40VA, 115V-to-24V control transformer. Confirm your existing transformer is rated 40VA with a 115V primary and 24V secondary before ordering.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker, then verify zero voltage with a multimeter at the line terminals.
2. Access — Remove the furnace control/blower compartment service panel.
3. Document — Photograph all primary (line) and secondary (24V) wire connections before disconnecting anything.
4. Remove — Disconnect the primary and secondary leads, then unbolt the transformer from its mounting bracket or junction box.
5. Install — Mount the new transformer, reconnect the 115V primary and 24V secondary leads exactly per your photo, and verify wire nuts are secure.
6. Test — Restore power, confirm 24V at the secondary with a meter, and run a full heat cycle.

Signs You Need a Replacement

• Furnace is completely unresponsive with a dead control board and blank thermostat.
• Low-voltage fuse blows repeatedly after replacement.
• No measurable 24V across the secondary terminals.
• Buzzing, overheating, or a burnt smell from the transformer.

Shipping & Returns

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