The Ultra 310 boiler with PhD (precision hydronic data) technology is a part of the Ultra boiler family. The boiler has a combustion efficiency of 93.3 percent; in low-temperature applications, such as radiant systems, efficiencies can go as high as 95.6 percent. This model can be used only in a floor-mount position. It has a net I=B=R rating of 252 MBtuh. According to the manufacturer, this boiler can be used in large home and small commercial applications, as well as multiple boiler system installations.
Weil-McLain, 500 Blaine St., Michigan City, IN 46360; 219-879-6561; 219-877-0556 (fax); www.weil-mclain.com.