Tempstar 40VA Transformer for TNK100J16B1 — 115V to 24V | Ships Today

Overview

This OEM control transformer (part number 1011626) supplies low-voltage power for the Tempstar TNK100J16B1 furnace. It steps the incoming 115V line voltage down to 24V and is rated at 40VA — enough to drive the control board, thermostat circuit, gas valve, and relays. The transformer is the heart of the 24V control system: when it fails, the entire low-voltage side goes dead, leaving you with a blank thermostat, no response on a call for heat or cool, and no movement from the gas valve or contactor. Failures are usually caused by a shorted secondary circuit, age, or a power surge.

Specifications

Compatibility

Factory replacement for the Tempstar TNK100J16B1. The 115V-to-24V 40VA rating is shared across many ICP-built Tempstar, Heil, and Comfortmaker furnaces, so this transformer fits a wide range of sibling models. Confirm your primary voltage and VA rating before installing.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker; verify zero voltage with a multimeter on both the line and 24V circuits.
2. Access — Remove the control compartment service panel.
3. Document — Photograph all primary (line) and secondary (24V) lead connections before disconnecting.
4. Remove — Disconnect the leads, remove the mounting screws, and take out the failed transformer.
5. Install — Mount the new transformer, reconnect the 115V primary and 24V secondary leads exactly per your photo, and secure all connections.
6. Test — Restore power, measure 24V across the secondary, and confirm the thermostat and controls respond.

Signs You Need a Replacement

• Blank or unresponsive thermostat
• No 24V present at the control board secondary
• Furnace completely dead on a call for heat with line voltage present
• Burnt smell or discoloration at the transformer

Shipping & Returns

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