The Brute™ 1000 & 1700 operate at firing rates as low as 100,000 BTU/Hr., resulting in low temperature thermal efficiencies as high as 99%, and 94% at full fire. The Brute 1000 & 1700’s two equally sized burners can modulate independently of each other, closely matching the boiler’s firing rate to the connected heating load, maximizing fuel utilization.