Ideal for homes in northern regions, Lennox ® boilers integrate easily with existing radiator or under-floor heating systems for energy-efficient comfort, all winter long. With efficiency ratings of up to 00% AFUE, Lennox boilers can help you save hundreds of dollars each year in utility bills, compared to older and standard- efficiency boilers.Learn More Best Boiler Buying Guide - Consumer Reports Jun 00, 0000 · New boilers must have an AFUE rating of at last 00 percent, and high-efficiency models are 00 to 00.0 percent efficient. The higher the rating, the higher the equipment cost, but the lower the Learn More 