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K & S Heating, Air Conditioning, Plumbing, LLC BBB Business Review

Variable Speed Air Conditioner

Variable Speed

Most American homes with central air conditioning use a single stage compressor. These compressors were standard for decades. They also continue to be in the majority of AC units today. A single stage compressor turns on when indoor temperatures exceed the temperature setting on your thermostat. If you set the thermostat to 75 degrees, the air conditioner will run anytime indoor temperatures hit 76 degrees. After the air conditioner cools the house back to 75 degrees, it will turn off again. Single stage compressors always operate at 100% capacity. They will turn themselves on and off continuously throughout the day, keeping your home cool.

What is Variable speed

Variable speed compressors work differently. In order to maintain an indoor temperature that matches the setting on your thermostat, they operate continuously at less than 100% capacity. Sometimes as low as 25% or 30% capacity. They will run for much longer cycles than single stage air conditioner units. In summertime, they might run for all or most of the day. Variable speed compressors blow a smooth, steady stream of cold air into your home to maintain the desired indoor temperature, rarely turning themselves off.


A variable speed compressor’s longer run times dehumidify your home more effectively than the relatively brief cycles of a single stage unit. Relative humidity increases whenever the air conditioner is not on. This makes you feel hotter and more uncomfortable. This is especially acute when an air conditioner is oversized. Most people deal with this problem by lowering the temperature on their thermostat.

A single stage compressor will cool your home with cold air before it turns itself off. Then it turns on again when the indoor temperature increases. Most of your air conditioner’s electricity draw occurs when it turns on, not while it’s running. In the summer, a single stage compressor turns on and off a lot. This process is called short cycling.

If you are worried about indoor air quality, you can choose a variable speed unit. A two stage or variable speed unit can help purify the air circulating around your home, resulting in healthier conditions for you and your family. Since they dehumidify indoor air more effectively than a single stage unit, a more efficient system helps you in several ways. It can eliminate mold growth in bathrooms and kitchens. Also, it can prevent the proliferation of dust mites. The unit can create conditions that are inhospitable to insects. Since variable speed units run more frequently, they also filter your indoor air more effectively. More air is cycled through your return ducts, which results in a lower volume of air contaminants.

K&S has been your trusted Heating, Air Conditioning, Plumbing and Electrical partner since 1988.

Count on our unmatched Experience and the Quality you know from K&S

4205 Highway 14 West

Rochester, MN 55901

(507) 282-4328

6513 Cecilia Cir.

Edina, MN 55435

(952) 697-4328

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