The Ultra with PhD (precision hydronic data) Technology® is a condensing high-efficiency gas boiler available in five sizes. With ratings ranging from 80 to 310 MBtuh, the boilers have 20-100 percent modulation. The Ultra control module automatically adjusts the blower speed and gas flow rate to modulate the boiler firing rate to closely match boiler output for space heating or DHW heating demand. Features include a cast aluminum mono block heat exchanger designed to operate in low-temperature condensing applications; a venturi mixing body that precisely mixes air and gas, providing higher efficiency; and a negative regulated gas valve that precisely delivers gas to the boiler. A variable-speed motor matches combustion output to the heat needed. All the boilers have efficiencies in the range of 92-93 percent AFUE, and up to 98 percent for common low-temperature applications.

Weil-McLain, 500 Blaine St., Michigan City, IN 46360-2388;

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