Problems With Two-Stage Air Conditioners

Necessity

• Two-stage air conditioners can be a worthy investment, but only in some areas. The furnace is expected to spend an average of 80 percent of its time in the first, partially active mode that saves money by using less power. If you need the first, lower-energy stage more than this, the two-stage furnace can be a waste. If you live in a mild climate, this first setting may be all you need, and you may be better served buying a normal furnace fitted to a smaller house. Otherwise, buying a two-stage air conditioner may lead to higher and potentially unnecessary installation costs.

Climate Issues

• If you live in a warm climate that alternates between mild heat and very hot summers, a two-stage cooling system can help you. But if you live in a cold climate, the two-stage cooling unit will not help you save money or cool your house more easily -- although a two-stage heating furnace may still be an efficient option. Climate is an important determinant of air conditioner operation, and not all climates allow the two-stage air conditioner to provide you with a lot of benefits. In cold climates, the furnace will receive signals from the thermostat to go immediately to the second stage, the state of full operation. If your climate is very cold, the furnace spends so much time in the second stage that it does not save a significant amount of money by using the low-energy first stage.

Airflow

• Airflow in a two-stage air conditioner is often managed through a variable blower that can switch speeds to match the different levels of unit activity. You may find that the blower is more complex than the air conditioner itself and must be adjusted to the needs of your duct system and house size. If you set the blower at an inappropriate speed, the air conditioner itself may not be able to cool your house more efficiently than a regular unit.

Leaks and Maintenance Issues

• Two-stage air conditioners are also subject to the same issues that all air conditioners may encounter. They can develop coolant leaks, especially when switching back and forth between stages. They can also become clogged with dirt and dust and require maintenance to work properly from season to season.