A zero clearance kit is available for this classic heating product from Enviro. The EF3Bi produces the most heat of any Enviro model. A double row of heat exchange tubes and up to 40,000 BTUs of heat input makes the EF3Bi a leader in the heating industry. Its beautiful design adds a touch of elegance to your home. The three-piece glass bay door provides an excellent view of your fire from almost any angle.