Zoning your AC system allows you to direct air to where it's needed via multiple thermostats installed in your home. A common use case is having one zone for the first floor and one zone for the second. Since warm air rises, the second floor often becomes a few degrees hotter than the first. With a zoned system, you can keep their temperatures at the same level. The cool air is automatically directed to where it's most needed. If you're tired of some rooms in your home being uncomfortable, read on to learn about your options for zoning your air conditioning system.

Add Automatic Dampers to Your Existing System

An HVAC technician can add an electronic zone control board along with automatic dampers to your existing central air system in order to provide zoning. The dampers control which zones are currently receiving cold air from your air conditioner's blower fan. When a thermostat in one of your zones senses that the temperature's too high, it sends a signal to the zone control board. In return, the zone control board opens the damper to that zone and closes the others. This directs cool air to where it's most needed.

The downside to this method is that something needs to be done about the excess pressure in your air conditioning ducts. Most air conditioners only operate at a single speed. An air conditioner that's designed to cool your entire house will generate extremely large amounts of pressure in the air ducts when it's only blowing air into a small zone. A traditional solution was to install a bypass duct that simply returned the air back to the air conditioner. Unfortunately, this results in the return air becoming very cold and can even cause the evaporator coils near the blower fan to freeze solid. Some houses had HVAC systems that were designed this way, but it's not ideal.

Instead, a better solution is to leave the dampers to all zones partially open. The zone that's requesting air will get the majority of the cool air from your air conditioner, and the leftover air will go to the other zones. This prevents cold, high-pressure air from being returned to the air conditioner. You'll be able to direct air around your home without worrying about your air conditioning system being damaged.

However, this has the downside of leaking cold air into other zones. If you don't care how hot the other zones get, then this is a waste of energy. Thankfully, you can solve this problem by upgrading to a variable-speed air conditioner.

Install Dampers With a Variable-Speed Air Conditioner

Variable-speed air conditioners can change both the speed of the compressor motor and the blower fan. When you use one in a zoned system, you'll be able to fully close dampers to zones that don't need cold air. In return, the air conditioner will simply slow down its compressor and its blower fan to lower the pressure in that zone's air ducts. This has the immediate benefit of providing greater energy efficiency. You won't waste cold air in zones that don't need them. At the same time, the zones requesting cold air will receive it at a pressure level that won't damage the air conditioner.

Overall, the best solution to zoning a central air system is to add automatic dampers and then upgrade to a variable-speed air conditioner. If you're on a budget, you can just install the automatic dampers and use your existing air conditioner. You'll still receive cold air where you need it, but it's not the most efficient way. Eventually, you can upgrade to a variable-speed air conditioning system that can make better use of the dampers in your air ducts.

Speak with an air conditioning professional to learn more.