Dunkirk’s DWB Series is ideal for both heating only (100 and 130 mbh) and combination heating and domestic hot water applications (150 mbh). It features: 85% AFUE efficiency; inducer fan and gas valve modulate for operation between 33% and 100% of capacity for fuel economy; chimney or horizontal vent; digital display with temperature indication, diagnostics and status symbols showing: heating mode, burner on and burner modulation level; durable, lightweight, one-piece steel jacket; 10-year limited copper heat-exchanger warranty; and two-year limited parts warranty.