Modu-Fire® is a combination of a full-modulation burner control and modular hot water boiler design. It operates across a 5:1 turndown ratio; it’s not step-fired, but it’s adjustable from 20% to 100% of rating. This direct-vent boiler achieves automatic air density compensation for consistent fuel-air ratio control in the face of changing supply air temperature, says the company. According to the manufacturer, powerful auxiliary control functionality is included, as are control functions that prevent short cycling and cold-end corrosion due to excessively low entering water temperatures. It has a 5-10-5 warranty.

Patterson-Kelley, 100 Burson St., East Stroudsburg, PA 18301; (website).

eProduct #186