is a heavy-duty barometric draft control engineered for precision regulation in oil-fired boilers

including round and square geometries

it utilizes a sensitive bimetal element to ensure accurate thermal response and pressure output modulation

preventing the heat exchanger from "soaking" in high temperatures

Trane TRR1581 Transformer 321894-706 is a heavy-duty barometric draftThe Trane TRR1581 Transformer is a heavy duty 75VA HVAC replacement part engineered for demanding residential and commercial applications. Designed to step down 200 230V primary voltage to a stable 24V secondary output, this component ensures consistent low voltage power for critical systems including furnace control boards, 24V thermostats, and contactor coils. As a genuine Trane OEM transformer, it eliminates the guesswork of universal fitments,