ICP 40VA Transformer for SH12516B — 120V to 24V Class 2 | Ships Today

Overview

This OEM 40VA control transformer (part number 1540352) steps incoming 120-volt line power down to the 24-volt Class 2 control voltage that your ICP SH12516B furnace's thermostat, gas valve, and control circuits require. The low-voltage 24V control system depends entirely on this transformer; when it fails, nothing in the low-voltage circuit can energize. A 40VA rating provides ample capacity for standard residential control loads. Common failure symptoms include a completely dead thermostat, a system that will not start, a blown low-voltage fuse, a burning smell from the control compartment, or a transformer that hums loudly and runs hot to the touch.

Specifications

Compatibility

Direct OEM replacement for the ICP / Tempstar / Heil SH12516B and other ICP-family equipment using the 1540352 transformer. Always confirm the existing transformer is rated 120V primary to 24V secondary at 40VA before ordering.

Installation Guide

1. Safety First — Disconnect power at the disconnect and breaker, then verify zero voltage at the transformer terminals with a multimeter.
2. Access — Remove the furnace service panel to expose the control compartment.
3. Document — Photograph all primary and secondary wire connections before disconnecting.
4. Remove — Label and disconnect the 120V primary leads and 24V secondary leads, then unbolt the old transformer from the bracket.
5. Install — Mount the new transformer, reconnect primary to line voltage and secondary to the 24V control circuit per your photo.
6. Test — Restore power and verify 24V across the secondary terminals, then confirm the thermostat and gas valve energize on a call for heat.

Signs You Need a Replacement

• Dead thermostat or display with line power confirmed present
• Repeatedly blown 3A low-voltage control fuse
• No 24V reading across the secondary terminals
• Loud humming, overheating, or a burnt-insulation smell

Shipping & Returns

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