Honeywell Ignition transformer ZT812 12600

The Honeywell ZT812 ignition transformer, SKU 12600, is a pulse-type ignition transformer designed for gas burner systems. It operates on a 220 V, 50 Hz supply and produces a secondary voltage of 15 kV. The transformer is rated for ambient temperatures up to 80 °C and has an ingress protection rating of IP54, indicating dust and splash water resistance. It is used to generate the high-voltage spark needed for ignition during the burner start sequence.

When selecting a replacement ignition transformer of this type, verify that the primary voltage and frequency match the burner control circuit, and that the secondary voltage and current are sufficient for the electrode gap. Check the physical mounting arrangement, terminal type, and cable connector pattern to ensure compatibility with the existing assembly. Inspect the high-voltage cable for damage before installation, as a faulty cable can cause spark leakage. Ensure the transformer is only energized during the ignition phase as commanded by the burner control.

Common failure modes for ignition transformers include internal short circuits, open windings, or insulation breakdown, which can result in no spark or a weak spark. Equipment symptoms may include failure to ignite, intermittent ignition, or the burner control locking out. Check the high-voltage cable for cracks or hardening, as this can cause spark leakage to ground and mimic a faulty transformer. Verify the primary supply voltage and connections before replacing the unit.