The initial products of the combustion from natural gas and oxygen are carbon dioxide and water. When combustion takes place, the water generated by the process is turned into vapor by some of the heat released. However, approximately 1,000 BTU per pound of water are required to convert the water into vapor and the vapor is lost into the exhaust gases during the process with a NON-condensing design. A condensing appliance has a heat exchanger specifically designed to condense the water vapor released by the combustion process and reclaim the 1,000 BTU per pound. Effective condensing is capable of reclaiming about 10% of the total energy being used by the appliance.