If you have a heat pump that's over ten years old, now's the time to start thinking about replacing it, not simply repairing it.

Why? Because today's generation of heat pumps are so efficient, they can often pay for themselves through decreased utility bills.

According to the Trane Home Comfort Institute, heat pumps usually last from 12 to 15 years, depending on their use. Your present unit is beginning to show its age when major components of the system such as the motor or compressor start making unusual noises or when the service calls start mounting up. It's at this point that you'll have to decide whether to repair the old system or replace it with a new one.

In the short run, replacing a major component costs less than replacing the entire system. In the long run, however, you may be missing an opportunity to greatly improve the overall efficiency of your system and save significant amounts of money in operating costs.

In recent years, heat pump manufacturers have made dramatic progress in increasing the efficiency of their units. As a result, it may make more economic sense to invest the money spent on repairs in a new, more efficient unit that will immediately lower operating costs.

Eventually, the more efficient unit should pay for itself through decreased utility bills. In the meantime, you'll gain the added benefits of greater reliability and longer warranty protection.

When looking at a new system, remember that the efficiency of a heat pump is indicated by two ratings, one for heating and one for cooling. The heating rating is called the Heating Seasonal Performance Factor (HSPF), the cooling rating is called the Seasonal Energy Efficiency Ratio (SEER). In both cases, the higher the number, the greater the efficiency and the lower the operating costs.

In order to attain the rated efficiency of the new system, the Trane Home Comfort Institute notes that it's important to replace both the outdoor unit (which includes the compressor) and the indoor unit (which includes the blower and evaporator) at the same time. Combining a new high efficiency outdoor unit with an old low efficiency indoor unit will probably not result in optimum performance.

It's also important to select the correct size unit for your home. A competent heating and cooling contractor, after a thorough inspection of your home, can determine how much capacity is required to keep your home comfortable.

Following installation of the new system, many dealers offer service contracts that call for periodic maintenance of equipment and, if needed, repairs. The cost of such a contract is usually well worth the investment.