This Texas company's gas-fired water boiler, called the Conservator 90, has an AFUE efficiency rating of 90%, enough to qualify for the Energy Star logo. Company officials say the cast aluminum heat exchanger is the key. It transfers heat three times faster than conventional cast iron. Low temperature supply and return water make it ideal for radiant systems without needing complex and expensive mixing devices. The Conservator 90 is also about 80 lbs. lighter than standard boilers and can be installed easily in basements, closets or alcoves. It can be used with PVC pipe for much of its venting, saving money.

Lennox Industries Inc., P.O. Box 799900, Dallas TX 75379-9900.