A Great Reason Why Your Air Conditioner Might Be Running All Day!

When you think of “slow and steady”, you don’t often think of air conditioners – especially when it’s hotter than blazes outside.  You’re likely looking for quick and fast indoor relief.  Select air conditioners and heat pumps offer a new technology that can help reduce indoor temperatures at 100% capacity, but also feature a “slow and steady” option. This option may actually help improve your home’s indoor comfort level while reducing energy consumption! So when it comes to home cooling – a slow and steady option may win the race on energy-efficient, refreshingly cool indoor comfort!

The Start vs Slow and Steady

Electricity usage usually surges each time an HVAC system turns on. The more often it has to turn ON, the more electricity it uses.

You may be thinking, “The more often my air conditioner runs, the more energy it will consume and the higher my utility bills will be.” But according to a study by the Department of Energy, “Operating fan motors or compressors at lower speeds for longer periods of time can lead to reduced total energy consumption.”¹

This is why air conditioners or heat pumps with compressors that can run at lower speeds for a longer period of time may actually use less energy than equipment with only one, 100% speed option. These energy-efficient compressors may increase the length of the unit’s run time, but they consume less electricity compared to units that only offer ON/OFF cycling! Slow and steady cooling may help you save on your cooling energy costs!

Compressors

An air conditioner or heat pump’s compressor creates the cooling capacity for the system and can come in single-stage, two-stage or variable-speed options. Each of these compressors offers the ability to run at 100% capacity when demand requires it.

Single-Stage: Traditionally, base model compressors are single-stage, which means the compressor runs full ON or is OFF.  With these models, your cooling system turns ON at 100% capacity and then OFF until your thermostat or control system reaches the temperature setting you have selected. 

For example, if your single-stage unit has a 3-ton capacity (measured in capacity, not weight), it will use all 3-tons or 100% capacity to cool your indoor space. The unit will cycle ON and OFF as many times as necessary to meet your indoor temperature request!

Two-Stage: Two-stage compressors offer two capacity options. It’s like having two units built into one — a low capacity one to handle a smaller demand and a larger one to meet heavier demands. If conditions exist that 100% capacity is not required, a two-stage compressor can operate at the lower speed, offering part-capacity to reach your desired indoor temperature.

While this may mean that your unit’s ON cycle time will be lengthened, the power needed to support the lower speed would be reduced compared to a simple, single-speed system.

Variable Speed: Variable speed compressor technology allows the unit to run at the speed that best meets your comfort needs coupled with energy-efficient operation. A variable speed air conditioner or heat pump is designed and engineered specifically to provide the output needed at the lowest consumption of power.   

Just like a car’s various gears, variable speed compressors can operate at various levels of output depending on the conditions. Systems with variable speed technology may run at full capacity on hot summer days or reduced capacity for milder days. It is a great energy-efficient option when compared to a single-speed unit.

Once the indoor temperature you set on the thermostat or control system is achieved, the variable speed unit will strive to operate at the lowest speed possible to deliver consistent, energy-efficient comfort in your home.

Because a variable speed air conditioner or heat pump can adjust capacity for demand, it may run longer than a single-stage unit under the same conditions. However, as the Department of Energy suggests, operating the compressor at lower speeds for a longer duration may reduce the total energy consumption required to cool your indoor spaces of your home without a loss of the unit’s ability to cool your home.

Added Benefits of Extended Run Times

A two-stage or variable speed system may run longer than your traditional single speed HVAC system, but at a level that requires less energy. But in addition to energy savings, this slow and steady operation offers some additional comfort benefits when compared to a single-speed unit:

Extended Dehumidification Process – Heat pumps and air conditioners use the refrigeration cycle process to cool your home.  During this process, moisture, in the form of humidity, is removed from the indoor air in your home. Longer run times create the opportunity for more indoor air to be dehumidified. This may improve the balance between temperature and humidity, providing you with more comfortable interior air.

Consistent Indoor Comfort – Two-stage and variable-speed technology may minimize the temperature swings often found with single-stage equipment. Rather than shutting down until your thermostat or control system recognizes the need for cooler indoor air, the optional run speeds prolong the set temperature of your spaces. This allows for a more steady and consistent comfort in your home when compared to the temperature fluctuations that can be associated with a single-stage compressor.

Air Filtering – The extended run time afforded by two-stage or variable speed units may increase the amount of time for the air to circulate and interact with filters or additional air quality system components. However, as with traditional systems, it is important to change out your air filters and indoor air quality essentials according to your HVAC dealer or manufacturer’s recommendations.

While extended run times can be beneficial with a two-stage or variable speed unit, single-stage air conditioners should cycle ON and OFF as demand requires. If you find that your single-stage air conditioner or heat pump is experiencing extended run times in comparison to normal operation, it may be a signal to contact your local licensed professional HVAC dealer for a system evaluation. 

1 Navigant Consulting, I. (2013, December). US Department of Energy. Retrieved from Energy Savings Potential and Opportunities for High-Efficiency Electric Motors in Residential and Commercial Equipment: https://energy.gov/sites/prod/files/2014/02/f8/Motor%20Energy%20Savings%20Potential%20Report%202013-12-4.pdf