Allanson 421-557 Transformer Els PW 17895 Pressure switches are safety-critical and

Pressure switches are safety-critical and must be matched exactly to the manufacturer's setpoints

are rated for up to 250Vac

reliable ignition by reaching peak temperatures within a 17-second warm-up window

acting as a critical safety override

Always verify the voltage output of your furnace control board before installation

Allanson 421-557 Transformer Els PW 17895 Pressure switches are safety-critical andThe Allanson 421 557 is a heavy duty oil burner ignition transformer engineered specifically for Arco and American Standard burners. This iron core transformer utilizes a 120V primary supply to deliver a consistent 10,000V secondary output at 23mA, ensuring a powerful arc for reliable burner ignition in demanding environments. Designed with a mid point ground configuration, the 421 557 features a high silicon steel core and large gauge copper windings