Boiler design efficiency

Now that the equipment is available commercially, more than half of the boilers Wisinski is providing quotes for to prospects are using this new design, which provides between 1 percent and 5 percent greater efficiency in the lower ranges and is comparable in cost to older models.

Boiler Efficiency related to the boilers energy output to the boilers energy input can be expressed as:

According to the 2012 ASHRAE Handbook–HVAC Systems and Equipment, combustion efficiencies range from 75% to 80% when in the noncondensing mode for most noncondensing boilers operating at return water temperature above 140 F, and 88% to 95% for condensing boilers operating at return water temperatures less than 130 F.

A traditional burner typically operates at lower efficiency ratings because additional oxygen is required for the burner to fire properly, and too much “excess air,” as the added oxygen is termed, can lower boiler efficiency.