Image for blue and red swoop graphic

The Importance of a Properly Sized HVAC System: Finding the Goldilocks Zone

By Aztil –

Image for The Importance of a Properly Sized HVAC System: Finding the Goldilocks Zone

Proper sizing is the most important part of any new HVAC installation. Whether you’re replacing your air conditioner, furnace, or heat pump, you must ensure it has the right capacity for its intended service area. This is key to avoiding hot and cold spots and abnormally high energy bills. Oversized and undersized appliances can’t work efficiently. They also experience countless performance problems, including short cycling, icing, overheating, and diminished humidity control. The first step when selecting a new HVAC system is to schedule a professional consultation. Our technicians can assess your home and household to find a properly sized HVAC system.

The Goldilocks Zone: Getting HVAC Sizing “Just Right”

The Goldilocks Principle states that if HVAC systems are not sized correctly, they can be too hot or cold. In the Goldilocks zone, the sizing for HVAC systems is “just right” and homeowners can expect even and consistent performance throughout their service lives.

Oversized Systems: What Happens When HVAC Equipment Is Too Large

HVAC sizing denotes the heating or cooling capacity of heaters, heat pumps, and air conditioners. If you choose a model that’s too large for your home, it will run short and intense heating and cooling cycles that use a lot of energy and cause accelerated HVAC wear. This is called short cycling, and with these short blasts of heated or cooled air, your living space will never be truly comfortable. Installing overly large units can also result in the frequent need for costly HVAC repairs and shorter equipment lifespans.

Undersized Systems: The Drawbacks of Installing Units That Are Too Small

Undersized HVAC equipment lacks the capacity to adequately heat or cool homes. Since it isn’t powerful enough to create the temperatures that residents want, undersized HVAC equipment often runs non-stop. This in turn leads to higher-than-normal energy use and faster-than-normal wear. Heat pumps, air conditioners, and condensing furnaces also impact an HVAC system’s ability to regulate humidity.

If your HVAC equipment is too small, your home could feel muggy or clammy. If your indoor humidity grows too high, you may even deal with problems like mold, mildew, and pervasive, funky odors.

Although smaller units tend to be cheaper upfront, they can cost a veritable fortune to use over time when they aren’t right for their service areas. In addition to higher energy bills, frequent repairs, and all-around uncomfortable living conditions, you’ll likely have to replace an undersized HVAC system much sooner than expected.

HVAC Systems in the Goldilocks Zone

Properly sized HVAC systems offer even and efficient heating and cooling and reliable humidity control. They sustain less wear, need fewer repairs, and enjoy longer lifespans.

The Benefits of a Properly Sized HVAC System

Correct HVAC sizing offers a wealth of impressive benefits, including:

  • Enhanced Comfort: With professional HVAC sizing, you can expect even air pressure, consistent air delivery, and uniform temperatures throughout all building areas. Proper HVAC sizing prevents hot and cold spots.
  • Enhanced Efficiency: HVAC systems in the Goldilocks Zone cost less than oversized and undersized units. With fewer and more effective heating and cooling cycles, your HVAC system will use less energy. In addition to smaller, monthly energy bills, you can also enjoy a smaller carbon footprint.
  • Greater Longevity: Modern furnaces, heat pumps, and ACs can last up to 20 years. However, this is only true with correct HVAC sizing.
  • Improved Indoor Air Quality (IAQ): Better humidity regulation from heat pumps, ACs, and condensing furnaces will stave off problems like mold and mildew. Balanced air pressure will optimize the performance of your HVAC air filter so that it extracts more dust, dander, pollen, pet hair, and other airborne particulates.

How to Find HVAC Equipment in the Goldilocks Zone

So, what’s the best way to determine the right HVAC size? Consider the following:

Professional Load Calculation With the Manual J

HVAC professionals calculate the air pressure required to distribute heated or cooled air throughout homes. They use the Manual J Load calculation. This accounts for:

  • Air duct sizes, materials, and design
  • Window sizes, types, and locations
  • The number of household residents
  • Insulation types and amounts
  • The layout of the buildings
  • The square footage of living areas

If you’re tempted to shop for a heat pump or AC on your own using the total square footage of your home as your sizing guide, you risk getting equipment that’s far too large or too small for your needs.

SEER and AFUE Ratings: Your Guides for Efficiency

SEER (Seasonal Energy Efficiency Ratio) ratings are also helpful when choosing high-performing HVAC equipment. A SEER rating denotes how well an HVAC system converts energy into cooled air. Shopping for an air conditioner with a high SEER rating will limit your energy spending over the next decade. When searching for a new heater, you want a furnace with a high annual fuel utilization efficiency (AFUE) rating.

Don’t Rely on Your Old System for Sizing Information

You might think that matching the size/capacity of your old HVAC equipment is a sure way to reach the Goldilocks zone. However, there’s a good chance that your current equipment wasn’t sized correctly or that your heating and cooling needs have changed. Finishing your attic or basement, adding to the building, or completing other major renovation projects can have a significant impact on your capacity requirements. The best way to ensure proper sizing for any new HVAC installation is by starting with a professional load calculation.

Let Aztil Air Find Your “Just Right”

At Aztil Air, we know just how important a properly sized HVAC system is for efficiency, comfort, and performance. You can count on us to quickly and accurately determine your HVAC capacity needs. We can also help you choose the perfect heating and cooling equipment for the Florida climate and its heating and cooling seasons. Get in touch with us today to schedule a consultation appointment.

Request Service

What Our Clients Think Of Us


I had 3 terrific technicians Paul Gross who found the problem fixed it but also found a leak so I had 2 technicians Jordan and Hero come and do the duct work I was so impressed by all 3 of them their knowledge professional and the enjoyment in doing the work for their clients I give all 3 of 10 gold stars😀
AZTIL is a real COOL company and Jackie my rep @Aztil responds ASAP when I get HOT on the phone. Seriously Jackie’s the nicest person. I don’t want to leave anyone out but Juan the technician goes above and beyond trying to solve my HVAC problems.
Alex was very thorough and knowledgeable.
Tino was professional and friendly. Thank you for a great service over the years.
I have used aztill air conditioning service for over 15 years. They have always been prompt and have always done a great job. I recently would like to praise Dana who came to my home today and his boss Jack for the great price. My wife and I feel blessed to have found them. They have been reasonable in their prices and the technician are right on point. Thank you Aztill Air. 😁😃
This was my first experience with Aztil as a new homeowner. I purchased a service agreement which I thought was reasonably priced. My first scheduled maintenance was this past week by Michael King .He was extremely professional, knowledgeable and very kind in explaining everything I needed to know. He made a great suggestion in which I followed through with. He’s an asset to this very professional company. Thank you Aztil and Jonathan for a job well done!
Mike came by for an A/C maintenance check up. He came on time and was very friendly and professional.
Response from the owner:Hi Larry, thank you for taking the time to leave us such a positive review about Fabio. We are delighted to hear that he was on time and provided excellent service. We appreciate your feedback and are glad that you had a good experience. Thanks again!
Excellent service very knowledgeable Niko send him hereafter
Tino was exceptional in sevicing both of my AC its. I renewed my contract with Aztil and I look forward in having Tino service me again Thanks for great service
I had to have my air conditioning HVAC system replaced. I bought RHEEMS from them nine years ago or just shy of nine years ago and I had to have the whole thing replaced. It had a leak. The pressure was down 3 pounds and to pay $475 only because I had a contract with them otherwise it would’ve been 675 to check for the leak.. I decided to replace it cause I knew it was around the corner anyhow. They installed it the next day I couldn’t have been more pleased. It was effortless. It took them a while because we had some rain on and off and they couldn’t be on the roof, but they came at 9:30 and they left at 3 o’clock. I thought they did very well. They left my house clean as a button just exactly the way they found it. They were very polite and did everything that they were supposed to do in a very neat and tidy and timely manner.
Jorge and David were the installers today. They were timely, professional, mannerly, exceptionally clean and efficient. And Sabrina in their office went beyond in responding as the cost of new units today is sticker shock!
Nico is absolutely amazing! Very informative and an excellent technician! This is the second time we’ve had him and he’s great
Response from the owner:Hi Kathy, Thank you so much for your wonderful review! We're glad to hear that you had an excellent experience with our service. We pride ourselves on our knowledgeable staff, and it's great to know that Ramon was able to provide you with such great service. We appreciate your feedback and hope to see you again soon!
After 40 hours without A/C in August we were saved by Rafael. He was polite, professional and courteous. He is an asset to the company. On another note, the scheduling system used for after hours is quite poor and needs to be looked into. Thank goodness Jackie called us and attempted to remedy the situation.
Naraldo Bunsie did an excellent job installing my new Trane A/C! Thanks !
Michael was very knowledgeable and efficient in providing service for us today. We’d love for him to come again
Your service techs and general service has improved since the corporate take over. Raphael Curci was efficient and kept us u[p to date on the progress of the installation. The person I'd like to call out as exemplary was Nico who guided us through the process and went out of his way to help us through this time. Ultimately the air handler was faulty and it took several visits to repair it. Meanwhile the handler leaked water all over the garage ceiling ruining it and causing damage to my model trains beneath. In addition the last tech broke my cable power supply which he had no business touching. I had to call Xfinity to come as an emergency for which they charged me $150.00. I will also be sending Aztil a bill for the repair of my ceiling and any damage done to my model trains.
Dana just finished a service call. He was very professional and explained to me what he was doing and gave me tips for the future. I have been an Aztil customer for many years and people like Dana keep me coming back.
Response from the owner:Hi Don, thank you for your kind words! We're so glad to hear that Angel did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Michael was efficient and thorough. I am very pleased with this service.
Response from the owner:Thank you
Juan was fantastic!
Michael was great, he called in advance arrived on time, very professional and knowledgeable, and got the job done in a timely manner, highly recommend.
Michael provided excellent service on unclogging our drain line and explaining what options we have to prevent it getting clogged in the future.
Naraldo was was a competent and efficient skilled worker..
Doesn't talk much but gets the job done quickly.

Replaced and rewired our new water heater in a very short time.

Left everything clean and Sparkling..

Would have him return anytime for the next project that might pop-up.
Response from the owner:Hi Erlene, thank you for your kind words! We're so glad to hear that Rafael did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana Dussault, the technician that came to fix my AC and installed a new compressor was so efficient and courteous and is an asset to Aztil. I was very happy with the work.
Nico and Adrian were great. Cleaned my ac and found an oil leak. Very personable.
Response from the owner:Hi Ilene, thank you for your kind words! We're so glad to hear that Niko and Adrian did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Rico was friendly and very competent & efficient
Response from the owner:Hi Shanti, thank you for your kind words about Ricardo and Aztil. We are so glad to hear that you had a great experience with us. We will make sure to pass along your positive feedback to Ricardo. Thank you for choosing Aztil!
Dana came on a Saturday in the pouring rain. Totally professional and knew what was wrong right away. Great job guys!
Dana was efficient and effective and answered all my questions. Top notch
I had a new central AC installed by Aztil today. Both of the techs, Jorge and David, were professional and friendly. I used Aztil because I have used them for service for over 10 years and have been very satisfied. I can recommend them for service and installations.
Tino was great. Answered all our questions and took his time to explain everything
They came quickly and Lazaro was very professional.
Lazaro Powery was fabulous!! He knew exactly what to do. He was very kind and I would definitely ask for him if I need any other issues with Aztel. You are lucky to have him with your company
Ramon came to fix my AC the day that it stopped working. He was pleasant, knowledgeable, and worked quickly. I highly recommend him and this company!
Aztil responded promptly to my ac problem. They were very professional and thorough. I recommend them highly.
Tino did a great job. He explained what our system needs and how much it would cost. We had someone else from Aztil here a few weeks ago and they did not take the time to diagnose our problem.
I recommend Aztil Air everything was done to perfection
Cody Richardson kept an open communication with us - letting us know his ETA & exactly what he was going to accomplish while at our home. Great service!
Tino was great! He explained everything so that I could understand what was happening with my air conditioner. Aztil is lucky to have him.
On time, efficient, friendly, knowledgeable, send him next time I need service. 5 Star
Excellent service!
Michael did a GREAT job he was prompt, courteous, and punctual.
I had a great experience with Moreno today. I got a text message with tracking info when he was on his way. He made fast, easy work on my AC system, and he helped me save money on my service by helping me sign up for their yearly service program. (Worth it!)
Jordan and Hero did an amazing job. They are both knowledgeable and professional.
Thank you Aztil Air Conditioning Company . We are so happy with the services That we received. Our air conditioner is nice and cool.We are so happy with your worker Cody he is a very nice
sweet hearted and honest young man that knows what he is doing.Every time he come and do tune ups or whatever is needed it is always done right. We look forward to you serving us again in 6 months.

Join The Club

Request more information by filling out the form below to learn about our Elite Cool Membership Program.

Highlights of the Elite Cool Membership Program include:

  • Members will receive priority service: Get top priority when scheduling service calls.
  • No overtime charges: We’re here for you anytime, day or night, 365 days a year, without any overtime charges.
  • A 15% member discount: Receive a 15% preferred discount on repairs not covered by the manufacturer.
  • Two maintenance calls per year: Benefit from two maintenance calls per year, spaced about six months apart.
  • AND MORE!

Need more information? Click below to call now!

Call Now

Our Partners


  • Carrier logo
  • Honywell logo
  • Mitsubishi Elctric logo
  • York logo
  • American Standard logo
  • Amana logo
  • Trane logo
  • Rheem logo
  • Ruud logo
  • Daikin logo