Furnace interface modules (WF-EZ3, LGR4, EM3, HP2, etc.) are designed to interface directly with a furnace fan center containing 24-volt transformer (40VA or larger), blower relay, and a "W" function to operate the fossil fuel furnace. If this installation is for an oil furnace with only oil control "T and T" terminals, a fan center will need to be added plus an isolation relay at the "W" terminal so only isolated contacts are connected to the oil burner master control "T and T". Another choice is to use a standard fan center and order EE-5053 relay with accompanying HD001 instruction sheet.
Electro Industries Furnace Interface Module, Accessory Type: Furnace Interface Module, For Use with: WarmFlo II EM-WU/EM-WD Dual Heat System