<p> Boiler Thermal Efficiencies Benchmark 1.5 Low NOx International, Inc. </p><p>Benchmark 1.5 Low NOx Efficiency Curves</p><p>As a condensing boiler, the BMK1.5LN boiler maximizes operating efficiency when applied in a system that leverages cold return water temperatures. As pictured below, the colder the incoming water temperature, the greater the boiler’s thermal efficiency.</p><p>Thermal Efficiency of BMK1.5LN</p><p>100</p><p>99 5% Input 98 50% Input 97 100% Input</p><p>96</p><p>95</p><p>94 %</p><p>,</p><p> y 93 c n e i c</p><p> i 92 f f E 91</p><p>90</p><p>89</p><p>88</p><p>87</p><p>86</p><p>85 50 60 70 80 90 100 110 120 130 140 150 160 170 Return Water Temperature, 20ºF Rise</p><p>In addition, the BMK1.5LN boiler shares the same type of inverse efficiency profile as its Benchmark counterpart. In simple terms, the lower the boiler’s firing rate, the greater it’s operating efficiency. At its lowest firing rates (or BTU/hr. inputs), the BMK1.5LN heat exchanger becomes greatly oversized in proportion to the load – allowing greater thermal transfer to take place. This means that the BMK1.5LN boiler saves the most energy during part load operations that characterize the majority of the heating season. And with the ability to perfectly match load anywhere between 1,500,000 and 75,000 BTU/hr., the unit will be operating at its greatest efficiencies when less robust equipment starts to cycle on and off repeatedly. </p><p>Rev. 12/26/07 C301.5</p>