What is Two-Stage Cooling?

Two Stage Air Conditioner

Two-stage cooling refers to the type of compressor that’s in the outside air conditioner or heat pump. Two-stage cooling systems have a compressor that runs at two speeds: high and low. This feature allows for two levels of operation depending on your cooling needs — full capacity on hot summer days or part capacity for milder days. It is a great energy-efficient option when compared to a traditional, single-stage unit.

It’s All About Demand!

There are times when your indoor space doesn’t need the full cooling capacity of your air conditioner or heat pump. This means that your cooling system doesn’t have to run at 100% in every circumstance. A two-stage air conditioner or heat pump is designed to adjust to load requirements in an energy-efficient manner to meet the indoor temperature set on your thermostat or HVAC control system.

If the outdoor temperature is high or you lower your thermostat or control system more than a few degrees, the compressor will likely operate at 100% cooling capacity to reach the desired temperature. If your air conditioner only needs to maintain the set temperature, it may not need to run at 100%! This is where two-stage technology comes in!

For example, if the outdoor temperature is 95°F and the thermostat or control system is set at 75°F, your system might stay at 100% capacity to reach and sustain 75°F. But if the outdoor temperature is only moderately warm, a two-stage system may be able to operate with less capacity to maintain the preset indoor temperature.

Benefits of Two-Stage Cooling

The two-stage unit may seem to run longer than a traditional single-stage unit, but this part-capacity operation offers energy-saving benefits that you will feel throughout your home:

  • Consistent Indoor Comfort – With its ability to adjust cooling output, your two-stage air conditioner or heat pump may minimize the peaks and valleys of cooling often found with the ON/OFF cycle of a single-stage unit. The low stage capacity is able to maintain the pre-set temperature longer than if the system turns off when it reaches the pre-set temperature. This allows for steady cooling comfort in your home.
  • Dehumidification - The extended operation of a two-stage air conditioner or heat pump runs longer which removes more moisture from the structure’s interior spaces. While the main job of the air conditioner or heat pump is to condition the air to a set temperature, these comfort-creating pieces of equipment may lower the indoor humidity level as a by-product of the cooling process.  Better humidity control leaves you with more comfortable interior air. When humidity levels are better controlled, you may be able to increase the set temperature on your thermostat or control system and still be comfortable in your home.
  • Energy-Efficient – You may think that because a two-stage cooling unit operates longer than a single-stage unit that it would use more electricity, but electricity usage peaks when a system turns ON. The capacity of the air conditioner or heat pump compressor changes to meet the cooling demand and therefore reduces energy consumption. 

While full cooling capacity provides indoor comfort on the hottest days of the year, the extended operation at the part capacity helps maintain the indoor temperature for a longer period of time and dehumidifies the conditioned air in the process. With two-stage cooling, your air conditioner or heat pump may help you enjoy steady and consistent cooling when compared to the single-speed unit.