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When It Comes to Air Conditioning, Size Matters Don’t Fall into the Trap of Buying an Oversized Unit: Beware of Cut-Rate Contractors Pushing One Particular Model!

Homeowners tend to keep their air conditioning units for a long time. Yet, if saving money is your goal, it could pay to weight the operating costs of your aging, less-efficient unit against the savings of upgrading to a new, efficient unit.

When you upgrade, avoid the common mistake of oversizing. Many people who have been struggling with an unreliable, older model, thing getting a larger capacity unit will make everything cooler. They believe since the unit will not be stressed, they will save operating costs. Not so.

A system that is too large not only costs more, and costs more to install, it operates inefficiently. A unit that is too large will breakdown more often and cost more to operate. Oversized heating equipment often creates uncomfortable temperature swings in the home. And oversized air conditioners do not run long enough to dehumidify the air. This gives rooms a clammy feel and even permits unhealthy mold growth in humid areas.

Often, when replacing their system, homeowners simply buy the same size they had before. Many older units were sized before the era of tightly constructed homes. It was not uncommon to install systems that were two to four times beyond the necessary capacity. If you have added new windows, caulking, weather stripping, or insulation over the years, you might be better served by a smaller system than the one you are replacing.

A popular formula to use for correct sizing is found in Manual J: Residential Load Calculation, published by Air Conditioning Contractors of America. It requires measuring walls, ceilings, floor space, and windows to determine room volumes. It considers your insulation’s resistance to heat flow (R-value) and estimates air leakage with a blower door test.

A good estimate also includes inspection of ducting and placement of the supply and return registers. Even the orientation of the house affects heat gains and loss. For example, overhangs can reduce solar gain through windows. Shortcut methods of sizing are only useful to get a ballpark estimate. Sizing based on gross square footage is not a good way to size for a final choice. The rule of thumb is one ton (12,000 BTU per hour) per 500 square feet of living space. This does not take into account design, construction, insulation, and other factors.

Replacing your air-conditioning unit with a new, more efficient model can lead to a windfall of energy savings. However, if you choose the wrong company to size your home and install your system, it can lead to a long list of headaches. Too many contractors will give you an estimate on a new system simply because it’s the system they have taking up space in their warehouse or it’s the cheapest system for them to sell!

We take your comfort, energy savings, and satisfaction to heart. We also do our best to provide air conditioning units for maximum value at the lowest price. If you know you need a new A/C, but have been putting it off, give us a call at 800-370-4328. We’re happy to give you a free estimate.

6 Signs That Your Cooling Equipment Has Become too...

"Very professional. And fast. Made sure I was happy! There was a size issue with the furnace, so they went all the way to Seattle to get me one that fit - and still installed it same day. It's wonderful that this company puts customer service first!"

– Robert & Laura H.

"Our experience with Black Hills, Inc. was very positive. Brittney was very helpful, informative and friendly on my initial call. Jake was awesome: friendly, informative, courteous and professional. I have no problem at all referring people to this company and they will be who I call whenever I have concerns about our heat pump. Thank you!"

– Sue B.

"Just wanted to let you know that all of the members of your team are as professional, prompt, efficeint, and polite as Tim Glasgo, you have assembeld a great squad! Congratualtions. 

– Steve D.

"Black Hills Heating and Air recently installed a new furnace in our home. My husband and I were extremely impressed throughout the entire process from our initial phone inquiry to the completion of the installation. Every member of the Black Hills team, was professional, knowledgeable, helpful, polite, kind and personable. We highly recommend them!"

– Michael and Melinda R.

"There very professional and polite, From the moment I called, they where to talk with and very informed, and scheduled right away, They where even early, from the moment I called untill the technician finished and left my driveway they where the best and most helpful repair company I have ever used, I would recommend them to anyone that needs HVAC help."

– Troy P.

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