How System Age Affects Furnace Repair
One key to fully understanding how to care for a heating and cooling system is to determine when the system was installed. A clue to the installation date will be the model number, which will reveal the date it was manufactured. After determining the installation date, repair patterns become quite common and predictable.
Central HVAC systems are composed of two sub-systems, the heating and cooling systems. The average serviceable life for the heating sub-system is about 20 years and the average serviceable life for the air conditioning sub-system is about 15 years. (That poses a problem when it comes to determining a date for replacement.) Keep in mind that annual maintenance service for your HVAC can extend the serviceable life of the system by about 5 years, so serving your system is advantageous.
The First Five Years
During the first few years of service, it is fairly certain that both sub-systems will experience few or no problems that require repairs. Most problems during this time will result from problems with the installation or faulty components. This makes annual maintenance even more important since ignoring regular maintenance can void the warranty that would cover the repair costs. Annual maintenance is especially important for gas-powered furnaces, to ensure the products of combustion—soot and water vapor, do not cause damage to the ignition system or heat exchanger.
Five Years Plus
Very little should change over the next five years, but a little wear can develop on electrical sensors or switches. However, the resulting stress can spread to other electrical control modules, so don’t ignore even small problems.
The stress of weakened parts should show up under maintenance inspections, a good reason to continue with a maintenance plan.
Ten Years Plus
This stage is rather critical in determining system longevity. Ignoring small problems will lead to a cascade effect, which often results in system failure. The most vulnerable parts remain electronic, and a maintenance technician will pay close attention to the sensors and control mechanisms that run your system. There are few mechanical moving parts; the blower motor is the most obvious example of a moving part. Problems with the motor generally show up early, in the first few years. After that, these parts are pretty reliable. The condenser unit also contains a fan motor and a compressor motor. This unit is more closely associated with air conditioning, but with a heat pump system they can be used year-round.
Inspection of gas-powered furnaces remains essential since the water vapor will promote rust on the burners and in the heat exchanger. Should the rust corrode the walls of either of these structures the results can be catastrophic.
After Ten Years
There are some central heat/air conditioner systems that last decades beyond the average lifespan. However, it is not wise to depend on the statistical anomaly for your system. After ten years, it is best to: