Heating systems more than three to five years old can usually be improved through addons, modifications, or improved maintenance. Most combustion units are oversized, for instance — particularly if the house has had insulation added since the unit was installed — and most have unsophisticated control systems. In addition, heat distribution systems can usually be improved through adjustment, new products, or in the case of air systems, tightening of the ductwork. The options presented here are among the most promising and practical, and should apply to the 65% of our nation's homes that are heated by forced hot air and the 10% heated by forced hot water. Remodeling contractors who educate themselves about these options
