Heat pumps need to be replaced when their performance declines. Warning signs include increased heating and cooling bills to maintain the same temperatures, uneven performance between rooms in the home, increased humidity in the home, increasing noise from the unit and frequent need for repairs.
Heat pumps have a normal life span of 10 to 15 years, but poor maintenance, restriction of the refrigerant lines, malfunctioning metering systems, moisture in the refrigeration system and lightning strikes can all cause premature failure. Regular inspection and maintenance make it more likely that a system will operate normally for as long as possible. Paying for a service contract is inexpensive compared to the cost of major repairs or replacement of the entire system.
Before deciding that a heat pump needs replacement, have it inspected by a technician from a reputable company and ask for an assessment of how long the unit can reasonably continue in service. If the technician recommends replacement of the unit, get quotes for the job from two or more companies but remember that cheapest isn't always best. If one provider in your area has a particularly good reputation for its service, it may be worth paying a little more to have that provider install and maintain your unit.