If summer utility bills are going through the roof, replacing anold air conditioner with a new, energy efficient unit can save asubstantial amount of money. The regulatory guidelines for manyappliances, particularly air conditioners, have tightened and thenew units use far less energy than the older models. The new SEERratings (seasonal energy efficiency ratio) require that heat pumpsor split air conditioning systems have a minimum SEER rating of 13,which uses 30% less energy than the SEER 10 air conditioners,according to the EPA.New air conditioners are available with SEER ratings up to 18,and as electricity costs rise, replacing the lower rated centralair conditioner with new ones will help families turn down thethermostat when the weather is hot, without the attendant sky highelectric b