The MAC1E used in conjunction with the UC1 Universal Control to easily interlock up to one additional 24 VAC , 115 VAC or millivolt controlled appliance with Fixed Speed Auto-Draft Inducer, Power Venters (Gas, Oil), Draft Inducers, or In-forcers. It activates the Venter through its connections to the UC1 and in turn relies on the UC1 Fan Prover safety circuit (P1 & P2) to allow its interlocked appliances to operate. Any pre/post-purge settings on the UC1 will be defaulted to the MAC1E. The MAC1E puts an end to difficult and costly job site wiring nightmares. Circuit board housed in oversized 18 gauge electrical box with multiple knock-outs for easy wiring connections. Tjernlund Multiple Appliance Control, Domestic