The Dominator Series from RBI offers flexibility and ease of installation and serviceability in a high efficiency, multi-stage boiler. At the heart of the unit is a sealed combustion chamber that can use outside air or mechanical room air for combustion. The chamber design, with fan-assist, multi-speed blowers and state-of-the-art staging control, offers high efficiency (84%) staged firing in a compact package and virtually eliminates heat loss. Offered in sizes from 300 to 2,100 mbh, with horizontal and vertical venting options, a Power-vent option for thru-wall venting, and a slide-out heat exchanger. A rugged frame and stackable design allows two units to be installed in the space of one small footprint. RBI.