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


On July 17th my air conditioning stopped working properly (it was set to 75 but was running at 82) and customer service scheduled a quick date for repair. Michael King was the technician they sent and he was very professional, friendly and explained what was being done. He was very thorough and made sure everything was resolved before he left. I would recommend Michael King for any A/C repair.
The a/c is again running great.
Harvey Meiselman
Boynton Beach FL
Response from the owner:Thank you for your review, Harvey Meiselman! We are glad to hear that Luis R was able to quickly resolve the issue with your a/c and that you are satisfied with his professionalism and friendliness. We value your business and look forward to assisting you in the future.
Juan came to our condo within two hours of me calling the company with a two week water leak that other companies could not fix within the past two weeks. He was therefore probably close to an hour to diagnose the problem, found what he thought was the problem, called me because I am out of town and had friends in the apartment to let them in, and he explained everything extremely professionally and calmly and told me thatafter the weekend since today is Friday they would probably try to get the part that’s needed which was a new ACP pan perhaps and did diagnose other problems. So far, we are extremely happy thank you. Kudos to Juan.
Jorge Rivera was extremely professional, pleasant, knowledgeable, informative and neat. He answered all of my questions and helped set up the WiFi for the thermostat. I would highly recommend him.
Juan , was very knowledgeable, polite, and help me set an appointment for the evening of the same day. He found the problem and solved it and found out that my unit was under warranty for me. I’m so glad for Aztil taking care of me and sending Juan, before I would need a replacement of my entire unit. 5 stars!!!
Dana was right on time. The job was very professional and clean. It was a pleasure to work with Dana and would request him to service my AC whenever needed.
Waited all afternoon for a service technician to arrive. The technician was late, but he was great! The best service check up ever!! Alex Molina is a 5 star tech! We’ve never experienced such a thorough check up!!! Asking for Alex from now on!
Thank You Aztill. Tino was Excellent, knowledgeable friendly service. Did a Great Job! I would recommend Aztill.
Excellent service. Requested an appointment this morning and the technician Paul Gross was here early this afternoon. He was very polite, knowledgeable and efficient. Made my day.
I had Aztil today come for my annual maintenance the technician Juan was the best technician. He was thorough efficient and explained everything he was doing. He truly gives above and beyond service and is a great asset to the company.
Response from the owner:Hi Jeanmarie, thank you for your kind words! We're so glad to hear that Juan did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Alex and Molina were very courteous and professional. My air ducts were cleaned and they were careful to clean and vacuum so as to be certain they could be proud of a job well done.
Response from the owner:Hi Debi, thank you for your kind words! We're so glad to hear that Alex did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Niko was prompt, professional and answered any questions very precisely and courteously. Patiently found problem issues and corrected them. Highly recommend.
Response from the owner:Hi Debi, thank you for your kind words! We're so glad to hear that Niko did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Niko 10/10 customer service!
Response from the owner:Hi Joulian, thank you for your kind words! We're so glad to hear that Niko did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Excellent technician
Response from the owner:Hi Jerry, thank you for your kind words! We're so glad to hear that Aztil did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Perfect in every way… professional, knowledgeable , clean, communicative.
Response from the owner:Hi Theresa, thank you for your kind words! We're so glad to hear that Aztil did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Albert Rodriguez did a great job!!!
Would highly recommend him!!!!
Response from the owner:Hi Gary, thank you for your kind words! We're so glad to hear that Albert did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana was able to diagnose and fix the problem. With my air c conditioner that two prior technicians could not. He left me with a feeling of confidence in his ability and I would request Dana for any future problems
Response from the owner:Hi Dennis, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Thanks Aztil for many years of service Tino was amazing did a great job on the ac units and was very professional I’m recommend Aztil for any ac needs.
Response from the owner:Hi Jose, thank you for your kind words! We're so glad to hear that Tino did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana Dussalt was awesome & very patient & courteous by ensuring our AC was functioning properly & explained in detail the issue that he resolved.
Response from the owner:Hi Sharron, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
ANTONIO MORENO services were a 10 where 5 was the highest!
Aztil is a great company where you can track your service teal time coming to your home. They’re right on time. They explain everything I’m impressed.
Response from the owner:Hi William, thank you for your kind words! We're so glad to hear that Antonio did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Albert is a great technician. He is very clean and courteous. I have been a customer of the company that they bought so it's been like a total of twenty eight years, and i'm very satisfied.
Response from the owner:Hi Mark, thank you for your kind words! We're so glad to hear that Albert did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Niko Garza completed a detailed diagnostic & flush of my home AC. Very professional and courteous. I highly recommend Aztil & Niko
Response from the owner:Hi Michael, thank you for your kind words! We're so glad to hear that Niko did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Paul gross was wonderful.
Response from the owner:Hi Diana, thank you for your kind words! We're so glad to hear that Pail did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Can I please 🙏 say ... a/c was down for about 14 hrs in a day in July 😡 then they sent there top star Danna & my man took care of everything !!!!!! 5 ☆☆☆☆☆
Response from the owner:Hi Darius, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana was great very helpful and knowledgeable.
Response from the owner:Hi George, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
I wanted to commend Dana Dussualt for his hard work at rectifying a substantial issue that I had with my HVAC system. It did require multiple visits but he stuck with it and figured out the issue and did get it resolved. Dana spent hours in the attic in the middle of summer working on getting this fixed. He is both a very hard worker and a pleasant individual. Dana is a credit to your company. In addition, the office staff worked with me in getting these repairs done by insuring we would get service on the date promised. Having no air conditioning in the summer is not a great experience. I have been an Aztil customer for many years.
Response from the owner:Hi Lyle, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana was on time and knew what he was talking about, highly recommend him.
Response from the owner:Hi Ginger, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Rhonda answered my call and was wonderful. Dana and Schuyler arrived within the hour and fixed my a/c problem. Cleaned everything up and would use Dana anytime.
Response from the owner:Hi Ricki, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Niko was fantastic... knowledgeable and professional... answered all my questions and did it with a smile... I would want to see him for all my service calls moving forward... thanks Niko!
Response from the owner:Hi Jim, thank you for your kind words! We're so glad to hear that Niko did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Jordan & Harold did a great job taking care of our system. Highly recommend them.
Response from the owner:Hi Janie, thank you for your kind words! We're so glad to hear that Jordan and Harold did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
The Aztil technician Dana was very professional, knowledgeable and courteous. He resolved my issue and made the visit seamless. .
Response from the owner:Hi Jeffrey, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Lazaro is an excellent Tech. Courteous and Professional. If possible ask for him for all your HVAC issues.
Response from the owner:Hi Les, thank you for your kind words! We're so glad to hear that Lazaro did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana was great. He was very knowledgeable. Did nice work Easy to understand. Highly recommended
Response from the owner:Hi Barry, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Jorge and Dave we’re extremely professional. The AC installation was done quickly and meticulously. I can’t recommend them enough!

I also want to give a shout out to Paul Gross. He was my initial contact with Aztil. He explained all my options to me and suggested the best unit for my home. Paul was able to get me a great price and I’m very grateful for his advice.
Response from the owner:Hi Wendy, thank you for your kind words! We're so glad to hear that Jorge and Paul did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Response from the owner:Hi David, thank you for your kind words and for being a valued customer.
Dana, my service tech did an amazing job to keep my AC up and running. He contacted me on his i, and was here in a flash.

He also updated me on the condition of the AC for the future, made some recommendations for me to consider.

Keep Dana on my service list and THANK YOU DANA!!!!
Response from the owner:Hi Jeanne, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana did a excellent job. He listened as to what was wrong as if he really cared. I would reccommend him to anyone. Very nice and respectable and he knew what he was doing.
Response from the owner:Hi Pat, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Niko was excellent. Very happy with his service. Explained everything and was very professional.

Yesterday no ac!! Yikes. Dana was the technician who did not leave our house until he discovered and fixed the problem. Believe me, he missed dinner and this was a Friday night. Couldn’t be happier. Dana was so professional and knowledgeable. So happy we bought from Aztil and have a service contract with them. If you ever think it’s not worth having the service contract in case of emergency, when you have no ac and it’s sweltering outside, you will be so happy you made a smart decision! Thank you Dana and Aztil.
Response from the owner:Hi E. R., thank you for your kind words! We're so glad to hear that Niko did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Ramon was very thorough.
Response from the owner:Hi Michael, thank you for your kind words! We're so glad to hear that Ramon did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Rafael
Was very informative, polite, and to the point in explaining warranty information, and what parts was needed for my air conditioner.

I look forward yo his next visit in 6 months.
Keeps us up to date.
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.
Ramon did an excellent job in servicing my air conditioners. He also called the office to get the permit issue resolved. He informed me that Aztil was recently sold and he is enthusiastic about the new management. I also see an improvement in the communication in the past month.
Response from the owner:Hi Michael, 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 Aztil was able to provide you with such great service. We appreciate your feedback and hope to see you again soon!
The service tech Ramon did an excellent job doing maintenance on my ac and fixed my plaster on top of the ac unit!! Highly recommend!!!!
Response from the owner:Hi Chris, thank you for your kind words! We're so glad to hear that Ramon did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
I scheduled a routine check up and Cody came to my home. He was so knowledgable and found issues with AC and fixed them on the spot. He also found a major issue on my roof and I immediately called the HOA. I will definitely be asking him to come back for my next check up

Excellent Customer service Kudos Cody !!
Response from the owner:Hi Evee, thank you for your kind words! We're so glad to hear that Cody did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
I appreciate the online appointment system and the follow up communication until the Tech arrives. Dana, the technician on my job was terrific. He was very thorough and courteous, willing to answer all of my questions with clarity. The only thing that keeps me from awarding a 5 was the price. The service was very satisfying and Dana was exemplary.
Response from the owner:Hi Brett, thank you for your kind words! We're so glad to hear that Dana did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.

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