Description
The Allanson 421-557 is a robust OEM ferromagnetic ignition transformer designed to provide reliable high-voltage spark energy for Arco and American Standard oil burner systems and other HVAC combustion applications. It features a 120 VAC primary input and delivers a 10,000 VAC secondary output at approximately 23 mA and 250 VA, ensuring consistent ignition performance under constant duty. Built with high-temperature internal wiring, midpoint grounding, and a double-pole ferromagnetic core, this transformer runs cool and quiet while meeting EMI/RFI noise suppression standards for compliant and dependable operation. It’s engineered to OEM specifications and often replaces legacy references like 421-353A and 421-393.
Key Features
- 120 VAC primary voltage — standard line input for oil burner ignition circuits
- 10,000 VAC secondary output with ~23 mA current for strong ignition spark energy
- ~250 VA rated output suitable for demanding burner ignition loads
- Double-pole ferromagnetic construction for stable, constant-duty operation
- Midpoint grounded core for enhanced safety and voltage stability
- High-temperature internal wiring improves durability under heat cycling
- Designed to meet burner manufacturer specifications for direct OEM replacement






