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Principles of Heating and Cooling

photo of girl sitting on floor of her bedroom with a fan cooling her off


Understanding the processes that help keep your body cool is important in understanding cooling strategies for your home.

Your body can cool down through three processes: Convection, Radiation, and Perspiration:Woman drinking water

  • Convection occurs when heat is carried away from your body via moving air. If the surrounding air is cooler than your skin, the air will absorb your heat and rise. As the warmed air rises around you, cooler air moves in to take its place and absorb more of your warmth. The faster this convecting air moves, the cooler you feel.
  • Radiation occurs when heat radiates across the space between you and the objects in your home. If objects are warmer than you are, heat will travel toward you. Removing heat through ventilation reduces the temperature of the ceiling, walls, and furnishings. The cooler your surroundings, the more you will radiate heat to the objects, rather than the other way around.
  • Perspiration can be uncomfortable, and many people would prefer to stay cool without it. However, during hot weather and physical exercise, perspiration is the body’s powerful cooling mechanism. As moisture leaves your skin pores, it carries a lot of heat, cooling your body. If a breeze (ventilation) passes over your skin, that moisture will evaporate more quickly, and you’ll be even cooler.

Ventilation enhances all these processes. That’s the reason we recommend running the fan of your furnace. If your distribution system is working properly, this would be enough to achieve more even temperatures throughout your home.

Here is the list of the top 3 most frequently asked questions this time of year:

How quickly should my A/C cool my house?Smiling man checking on an equipment
After the humidity is removed, about 1 degree an hour on a 95F day. Know that it can take up to 24 hours to remove all the humidity from your home, and during that period of time, the temperature will not drop at the same rate.
Be aware that setting the humidity level at 52-54% on a humid day is very reasonable. Homeowners need to be careful of abrupt changes in the humidity of environments, for example, if they are coming in and out of the house.

Will a dirty furnace filter or dirty condenser affect the cooling?
Yes, they will affect airflow and therefore affect the cooling. Usually, part of the central air conditioning system (A-coil) sits atop the furnace.
To keep your system at maximum efficiency change the filters regularly and ensure the condenser is clean. Cottonwood could be a problem.

My A/C is not cooling well could it need a recharge?Smiling man checking a unit
Air conditioners are sealed systems and are not supposed to lose their refrigerant. If you do need more refrigerant, you likely have a leak in the system and should have it looked at.

Heating and Cooling education is just part of the deal when you work with Standard. Our technicians take the time to answer all the questions you may have. It’s been since 1930, and we’ve served over 475,000 satisfied Twin Cities homeowners. Our customers value the high quality of our workmanship and say we are prompt, reliable, friendly, and professional.

For more visit the Department of Energy
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