The R8285D transformer/relay provides low voltage control of line voltage fan motors and auxiliary circuits in heating, cooling, or air conditioning systems. Control mounts to a standard 4 x 4 1900 electrical box. This single control accepts 120, 208, 230 voltage and provides 24 volt secondary control voltage. DP-ST contacts allow for single speed fan operation, while providing additional auxiliary contacts for operating peripherals. Incorporates the use of replaceable R8222 relays for ease of service. Used by numerous boiler manufacturers for system control. Relay auxiliary contacts rated for millivolt use.