One Hour 101: Sizing Your New HVAC System

The Importance of Being Educated

When it comes time to replace your furnace and air conditioner, it’s important to approach the matter with as much knowledge as possible. One Hour provides free estimates and consultations, which allows us to pass on valuable information and advice. However, all customers should do research of their own before having one of our comfort advisors out to their home to discuss replacing their HVAC system.

Sizing Your New Hvac System

Oversized air conditioners can lead to a number of headaches. It may seem odd for a company that sells and installs air conditioners to caution against going too big, but a properly designed system will make our customers happy and will keep us from running warranty calls.

We’ve compiled a list of problems that can arise if a new HVAC system is not sized properly:

  1. Initial Costs – Yes, an air conditioner with a larger capacity costs more than one with a smaller capacity. Why would you pay for more tonnage than you need? Better yet, why would a reputable company try to sell you a system that you don’t need?
  2. Operating Costs – An oversized air conditioner will cycle more often than a correctly sized unit. Think of it as a marathon runner vs. a sprinter. The marathon runner is a correctly sized A/C. It may take a little longer to cool the home, but it provides a uniform climate over a large area by efficiently utilizing energy and airflow. The sprinter, in this case the oversized A/C, huffs and puffs in short bursts, which leads to uneven climatization and degraded system efficiency due to frequent starts and stops. Those frequent starts and stops are a deadly thing for an air conditioner’s compressor.
  3. Comfort – As mentioned above, an oversized system cycles much more frequently than intended. These short bursts of operation will heat or cool a home unevenly due to the typical placement of the thermostat. Most thermostats are placed in a central location in a home. This means that on particularly cold and hot days, the outer rooms of a home could be colder or warmer than the middle of the house by several degrees, simply due to the fact that by the time the thermostat senses it needs to call for heat/cool the perimeter is already cold. Even when it does finally call for heat/cool, the
  4. Noise – An oversized HVAC system will cause quite a ruckus. The system itself will be louder than it should be just by way of being bigger than it should be. It will also likely cause problems with airflow, which can make for noisy ductwork, grilles, and diffusers. If you don’t want your home to sound like a freight train delivering teapots, size your system correctly.
  5. Air Quality – Another side-effect of short cycles is air quality. If your HVAC system is running only 15-20 minutes every hour, the benefit of air filtration is significantly cut. In order to filter particles like dust, pet dander, allergens, and odors, your system’s fan must be running.
  6. Humidity – A properly sized air conditioner does a great job of removing humidity from your home. Humidity removal occurs when air is circulated over a sufficiently cold coil. The optimal time for humidity removal usually starts in the 10-20 minute range of operation. If your system is running for 20 minutes, it’s possible that your air conditioner isn’t removing humidity at all!
  7. System Lifespan – The short cycling of an oversized air conditioner can significantly cut down on the life of a compressor. Similar to how drivers should avoid stop and go traffic, a compressor strains every time it starts and stops. The added strain of 3-4 startups per hour for an oversized unit versus 1-2 per hour for a properly sized one cuts the expected lifespan by years!

How to Size Your New System Correctly

How does One Hour avoid oversizing HVAC systems we install? By performing an engineering analysis (a heat load calculation), we take into account floor space, insulation, floor type, doors and windows, lifestyle, and several other factors that will give us an accurate measurement for your home.

If you’d like to have a One Hour comfort advisor perform an engineering analysis on your home, call us today at (816) 354-1077. Our consultations are free of charge. We’ll be glad to answer any questions you have in person, on the phone, or via e-mail.