ICP 40VA Transformer for SH7512B — 120V to 24V | Ships Today

Overview

This is the OEM 40VA control transformer (part 1540352) for the ICP / Tempstar / Heil SH7512B. It steps 120V line voltage down to the 24V required to power the control board, thermostat, gas valve, and low-voltage relays. The transformer is the heart of the furnace's low-voltage circuit — when it fails, the entire 24V side goes dead, leaving a blank thermostat and a furnace that will not respond to a call for heat. The most common cause of failure is a shorted 24V control wire that overloads and burns out the secondary winding.

Specifications

Compatibility

Engineered for the ICP / Tempstar / Heil SH7512B and other furnaces in the same family that use a 120V-to-24V 40VA control transformer. Confirm your existing transformer's primary and secondary voltage and VA rating against the failed unit before installing.

Installation Guide

1. Safety First — Disconnect power at the service switch and breaker, then verify zero voltage at the transformer leads with a multimeter.
2. Access — Remove the furnace control / burner compartment panel.
3. Document — Photograph all primary and secondary wire connections before disconnecting.
4. Remove — Disconnect the 120V primary and 24V secondary leads, then unbolt the transformer from its bracket.
5. Install — Mount the new transformer and reconnect primary and secondary wiring exactly per your photo.
6. Test — Restore power and confirm 24VAC across the secondary and a normal call for heat.

Signs You Need a Replacement

• No 24V control power — thermostat is blank or unresponsive.
• Furnace will not start despite a valid call for heat.
• Measured secondary voltage is zero or well below 24VAC.
• Visible scorching, swelling, or a burnt smell at the transformer.

Shipping & Returns

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