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HVAC Sizes: How do I know what size HVAC I need?

June 11, 2019

When you are thinking about buying a new HVAC system, an important consideration is the sizes of available equipment. Just think: this new cooling and heating system will be serving your home for ten years or longer. It’s important to get this right!

For cooling and heating systems, it’s important to get the right size of equipment.

  • Bigger is not better – Rounding up might seem like a good idea, but over-sizing HVAC equipment can lead to lots of operational problems. An HVAC system that is sized too large will turn on and off regularly. That’s not only annoying for the people in the space, but the incessant startups will wreak havoc on your energy bills. And, it can lead to a shorter equipment lifespan.
  • Less is not more – It goes without saying that you don’t want to undersize your equipment. An under-sized HVAC will not be able to keep up with demand. Even if you think you’re not using very much of your HVAC system, consider the days where your home gets the heaviest use. For example, friendly gatherings or bake-offs in the kitchen. You want your system to be able to keep up in those scenarios!

Now you know the importance of investigating sizes of HVAC equipment. So how do you get to a number?

The Trouble with Using the Same HVAC Size

A lot of homeowners think that if they are replacing an HVAC system, they don’t need to worry about sizes. Just use the same size as the existing HVAC. Right?

The truth is that this approach can be problematic.

So before you get too far down the path in ordering a new heating and cooling system, consider if you’re experiencing any of these issues with your current setup:

  • Does your HVAC seem to be running constantly, or only turning off very briefly?
  • Conversely, does your HVAC system kick on and off, rarely staying on for more than a few minutes?
  • Are there areas of your home that aren’t being cooled or heated to your comfort levels?

If you are having any of these troubles with your cooling and heating system, you will be better off looking at different sizes of HVAC equipment. Our highly-trained technicians at Brody Pennell can help you choose the appropriate size system for your home.

Special Considerations for HVAC Sizes when Replacing

Homeowners that are replacing their HVAC should consider improvements that have been made to the home. Changing physical features of the home, adding energy-saving improvements, or remodeling spaces can impact the size of an HVAC system.

When you meet with a licensed contractor at your Los Angeles home, be sure to tell him or her about any changes you’ve made to the home since your current HVAC system was installed. Some of these items include:

  • New windows
  • Improved roof insulation
  • Additions of new spaces
  • Remodeled areas like kitchens, laundry rooms, bathrooms, or home gyms
  • Finished out spaces like attics, basements, or garages

Determining the Right Size of HVAC Equipment

So, what size does your air conditioner or furnace actually need to be?

If you’re building a brand new home, adding a new space, or you have done many renovations to your home, a load calculation needs to be performed.

load calculation takes into account a number of variables. For example, how many windows you have, the orientation of your home in comparison to the sun, and insulation in your walls and roof. A load calculation will also include the heat generated by the people, lights, and electronic devices in your home, just to name a few. An industry standard for load calculation is the Air Conditioning Contractors of America (ACCA) Manual J method.

When you have a final load value from the calculation, you’ll know what size your HVAC needs to be.

Isn’t there a simple rule of thumb?

If you’re doing research about HVAC sizes, you might find simplified methods for determining the load. For example, a certain number of tons per hundred square feet. Simple online tools will also spit out numbers for you. Homeowners should use caution when using these tools. These tools make sweeping generalizations about your home, and may not be able to produce accurate numbers.

Work with the best… and save money, too

The team at Brody Pennell has been in the heating and air conditioning business for more than 70 years. We understand how to size equipment correctly the first time by doing industry-standard heat load calculations.

Right now we are offering great specials on HVAC systems of all sizes. With the Carrier Cool Cash program, you can get up to $1,650 off a new HVAC system. You can combine this deal with other incentives, like utility rebates and financing. Now is a great time to buy if you are on budget – this is the best deal of the year.

Between our long history in LA, and our partnership with the best equipment manufacturers, our team can then provide a range of solutions that will best meet your needs. Give us a call to schedule an appointment today!


About The Author

Brody Pennell

Since 1945, Brody Pennell Heating & Air Conditioning is the committed to helping homeowners in the greater Los Angeles area experience total home comfort. In 2021, the readers of the Los Angeles Times voted Brody Pennell the Best HVAC Company in the area.

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Maggie G.
1711675784
Our new AC guys were great! Thank you Juan Molina and Richie for squeezing into our tight attic and for being so professional (and quiet!) during my work-from-home meeting!
Joe S.
1711667055
Steven and Phillip Y. Very professional and got the job done. I’m very happy thank you so much.
Ushma A.
1711663830
Jaun molina and Kyle mike and Raul Ibarra bros work well as a team and did a great install were the best and did an excellent job explaining the issues and finding solutions
Danielle A.
1711662970
Rene and Morales were wonderful! Super helpful in getting our commercial HVAC working again and troubleshooting the main issue with why the heat wasn’t working. Super grateful for their ability to come the same day as well.
W. Peter I.
1711656616
Kevin and David E were polite and fabulous. Thx you!
Paul H.
1711656181
Ruben and Esteban were extremely friendly and clear on what work they had done. Highly recommended
Letty C.
1711655993
Anthony Manzo and Alessandro A great service
Peggy S.
1711655360
James and Armand did a great job!
Terry P.
1711649483
David M and Michael S were both very detail-oriented with exceptional customer-service mentalities and communication skills. They clearly described their findings and what services they would be able to offer. I felt confident that they had thoroughly investigated our HVAC system issues and considered all possible solutions before offering their recommendations. Moreover, they provided recommendations in a manner that did not feel as though they were pressuring us into making a purchase on-the-spot but rather allowed us to come to a decision on a timeline that worked for us. As a team, they spent multiple hours evaluating our HVAC system and left no stone unturned or question unanswered.
Danielle D
1711649263
Exceptional service; professional, courteous, and articulated the work in detail. Ivan D. And Daniel L are excellent. Highly recommended company and team. Thank you.3/28/2024 Daniel B., Ivan D. and Dio were fantastic. Excellent work!!
Rodrigo C.
1711644777
Thank you James H. For your work! The AC is absolutely working better and thank you for the finding a third filter that no one else before could! What a rockstar. Thank you for your labor, we'll see you in three months1
Joe H.
1711642345
Rene and Leo Morales show up early or on time, their attitude and work ethic provide satisfaction. They are very pleasant and know what they’re doing.
Alana D.
1711577999
Juan A and Marco did a great job. Friendly service and thorough.
Martha M.
1711572741
Shawn was fabulous. So professional and so careful of our home.
Jill S.
1711572064
Rene and Leo Morales did a great job today. Brody Pennell is the best!
Connie W.
1711569518
Juan Molina was on time, professional, and picked up a problem with the voltage in our AC compressor voltage that would help prolong the life of the unit3/27/24Timothy, Josh M, and Kyle they were very thorough and answered our questions well.Great explainations and very pleasant.
Dan M.
1711565107
Google does not allow multiple reviews, so editing this to update on the most recent visit.Jason and Armando were assigned and did a fantastic job. They were prompt, courteous and professional. They upheld the high-expectations that I have for Brody Pennell. They were both super friendly and through. They covered all of the expected work and also looked into another issue I was having. They were both able to provide solid advice on how to proceed.From a business standpoint, the scheduling, confirmation, and information regarding the visit was top notch. I felt informed every step of the way and the information was accurate.%%%%%%%%%%%%%%%%%%%%%%%%Review from 2023:This review is specific to the HVAC maintenance repair completed this spring. I setup the appoint and received confirmation and a reminder the day before. Once the technician was assigned, I received additional communication that they were on their way.Jose C. arrived and was prompt, courteous and professional. He chatted with us first to talk through what he was going to do, got a lay of the land and then went to work. He took time once he was completed to share his findings, the work he did and discuss next steps. He captured photos of the before and after and documented his work well.He also took the time to call dispatch/office to clarify some confusion, which was great. All in all, great experience from start to finish.
karen S.
1711564697
Juan Molina, Mike Stafford, and Richie Salazar were exceedingly knowledgeable and efficient in servicing our HVAC. They used shoe covers and drop cloths so our condo was clean when they left!
Eliette K.
1711564203
Daniel and Pablo did a great job with the HVAC maintenance.
Nathalie K.
1711562137
James & Alberto were very courteous & thorough. Thank youNicole Karsenty Ligeti
Obele A.
1711555122
René and Leo Morales were fantastic! Very personable. Excellent customer service. They took the time to explain the situation and options for how to proceed. Stamp of approval granted.
Christopher F.
1711521527
Daniel Avila and Pablo Lopez provided very friendly and efficient service.
Kathy I
1711516687
I had to take the time to update my review and thank and compliment Ashton K. and his team of installers Mike, Raul, Elario, and Juan DS who installed our new furnace. Ashton’s knowledge and follow up has been fantastic. The installers workmanship was excellent. They were all professional and respectful and kept our home neat and clean after they finished the installation. The furnace is working perfectly. Our follow up appointments with Jose Rivera, Jonathan A. and Ramiro S. were also handled with the same professionalism.I would highly recommend Brody Pennell. The quality of their furnaces and workmanship are excellent.Juan Molina and Ashton K provided me with great service today. They were both very thorough and detailed in explaining the technical problems that were occurring with my heater. I was very pleased with their high level of service and professionalism.
Jenny W.
1711509954
Today when we had someone come to look at our ancient HVAC, I never imagined that we could be shown in great detail the inner workings of the thing. David Mars with his kit of diagnostic tools and his supervisor Fabio Lopez (I think is Lopez) showed us in photos and videos (even with a tiny camera on a gooseneck that showed inaccessible parts) and explained at length the significance of all the horrors we were looking at. We are now scheduled for installation of a new HVAC tomorrow. I’ll post again if my experience changes but so far we are impressed.
Susan A.
1711495997
Daniel B and Alessandro A were fantastic today! They did a great job doing the maintenance on my system and were just lovely to work with. Great job!
ROSALINDA M.
1711490429
As always Juan Molina provides exceptional service with thorough expertise and the most pleasant and courteous manner. He is. A credit to the BP brand of excellence in service.
Mike B.
1711477483
Timmothy was the best tech that ever came to service my system. He was friendly and thorough and went above and beyond to make sure the job was done to my satisfaction
Lori P.
1711433844
Cristina P.
1711418295
Juan Molinas and Dave ocampo came to my condo for my air maintenance. I’m so impressed with their politeness, care and knowledge. They went above and beyond my expectations. I highly recommend Brody Pennell.
R A
1711416532
I really enjoy the service guys here. David and Alex were really lovely and the last time Benny was so great. I was already planning on getting a new unit. Wasn’t a huge fan of the particular supervisor I dealt with in terms of sales, but we were able to finalize with Michael and I would like to believe we all have bad days. Michael made us feel much more confident. I will update when I have my new system. I do always appreciate that they are very respectful and adaptive to my medical needs.
Bill C.
1711410254
Kevin and Robert Jadds showed up the same day, went underneath the house, and couldn't have been more pleasant and professional. I have signed up to use Brody for all my HVac needs going forward.
Steve B.
1711405223
Spencer, Mike and Ariel all were exemplarySpencer smartly contacted Mike to ascertain the full parameters of our problem and while waiting initiated with Ariel our condenser maintenance. And Mike presented us with options that satisfied our needs. Great team
Arik M.
1711404349
Timothy and Juan D. Did an excellent job cleaning my mini-split unit indoor and outdoor.
Maria T.
1711401681
Anthony Manzo David EThey did a great job trying to figure out how to fix. Great job guys!
cynthia C.
1711397456
Timothy TranJuan Dejesus
CRMCSYS
1711393886
Marco Ayala (technician), Juan U. (apprentice) and their supervisor Ashton were courteous, patient and thorough. They reviewed the problems I have with my Carrier unit and explained why I needed it replaced. I was given the choice of 3 new models with price and labor for each. They offered to contact my HOA’s management company for the roof installation and will arrange a city inspection after the work is completed. I would not hesitate recommending Brody Pennell to family and friends.
Kerrie K.
1711390619
Benny was thorough in his inspection, and he went over and above in answering my questions and giving me sound advice. His patience and professionalism are so rare these days. Thank You
Dylan L.
1711387435
Timothy Tran and Juan D. were exceptional!!!
Joe B.
1711226631
Excellent work!! Very cordial and informative. Super attentive. Right on time. All great.
Kimberly B.
1711222248
Wanted to give a big thanks to Mike, Raul, Rosendo & Nathan from Brody Pennell Plumbing & Heating for the installation of our new HVAC system, the professionalism of the guys & quality of the installation was top notch!!!
Isabel W.
1711145412
Juan Molina and Freddy did a great job! Very clean and very respectful :)
Dagoberto V.
1711141678
Great guys both Juan and Tony hope to see them next service stay safe ., great to deal with and very good knowledge
David O.
1711136928
3/22 - clean, fast, courteous job with Troy and Phil. Very polite and thorough! Another fantastic job by the people at BrodyYet another pleasant service experience with Marcos!!! Also told me about an air scrubber install that Brody can do as well.10/9: another great job by Steven
Diane S.
1711134416
M H.
1711131246
Today Armando and Jadds provided the professional technical service that Brody Pennell has always delivered for years.Our A/C / Heating system is getting older, but the excellent routine maintenance and advice Brody Pennell has given me keeps everything running smoothly.
Khemsuay P.
1711129519
03.22.2024Juan Molina and Freddy are very god at what they do, freindly and knowledgeable.I really recommend them .Enmity is the best !!I really recommend him
Deke S.
1711126198
Rene & Leo. On time. Friendly. Respectful. A+++
Mario Sanz S.
1711125163
Very easy to connect and schedule an appointment for my heater maintenance.Maria was on time, very knowledgeable, friendly, and attentive to all my questions, providing clear responses to each.
Mo S
1711059929
Timothy and Mike provided one of the best customer experiences I ever had! Their kindness, thoroughness, knowledge, and expertise were top notch! They went beyond the call of duty and helped us tremendously! Thank you immensely!!
Ellen C.
1711057975
Rene and Leo were very kind and efficient!
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This field is for validation purposes and should be left unchanged.
Maggie G.
1711675784
Our new AC guys were great! Thank you Juan Molina and Richie for squeezing into our tight attic and for being so professional (and quiet!) during my work-from-home meeting!
Joe S.
1711667055
Steven and Phillip Y. Very professional and got the job done. I’m very happy thank you so much.
Ushma A.
1711663830
Jaun molina and Kyle mike and Raul Ibarra bros work well as a team and did a great install were the best and did an excellent job explaining the issues and finding solutions
Danielle A.
1711662970
Rene and Morales were wonderful! Super helpful in getting our commercial HVAC working again and troubleshooting the main issue with why the heat wasn’t working. Super grateful for their ability to come the same day as well.
W. Peter I.
1711656616
Kevin and David E were polite and fabulous. Thx you!
Paul H.
1711656181
Ruben and Esteban were extremely friendly and clear on what work they had done. Highly recommended
Letty C.
1711655993
Anthony Manzo and Alessandro A great service
Peggy S.
1711655360
James and Armand did a great job!
Terry P.
1711649483
David M and Michael S were both very detail-oriented with exceptional customer-service mentalities and communication skills. They clearly described their findings and what services they would be able to offer. I felt confident that they had thoroughly investigated our HVAC system issues and considered all possible solutions before offering their recommendations. Moreover, they provided recommendations in a manner that did not feel as though they were pressuring us into making a purchase on-the-spot but rather allowed us to come to a decision on a timeline that worked for us. As a team, they spent multiple hours evaluating our HVAC system and left no stone unturned or question unanswered.
Danielle D
1711649263
Exceptional service; professional, courteous, and articulated the work in detail. Ivan D. And Daniel L are excellent. Highly recommended company and team. Thank you.3/28/2024 Daniel B., Ivan D. and Dio were fantastic. Excellent work!!
Rodrigo C.
1711644777
Thank you James H. For your work! The AC is absolutely working better and thank you for the finding a third filter that no one else before could! What a rockstar. Thank you for your labor, we'll see you in three months1
Joe H.
1711642345
Rene and Leo Morales show up early or on time, their attitude and work ethic provide satisfaction. They are very pleasant and know what they’re doing.
Alana D.
1711577999
Juan A and Marco did a great job. Friendly service and thorough.
Martha M.
1711572741
Shawn was fabulous. So professional and so careful of our home.
Jill S.
1711572064
Rene and Leo Morales did a great job today. Brody Pennell is the best!
Connie W.
1711569518
Juan Molina was on time, professional, and picked up a problem with the voltage in our AC compressor voltage that would help prolong the life of the unit3/27/24Timothy, Josh M, and Kyle they were very thorough and answered our questions well.Great explainations and very pleasant.
Dan M.
1711565107
Google does not allow multiple reviews, so editing this to update on the most recent visit.Jason and Armando were assigned and did a fantastic job. They were prompt, courteous and professional. They upheld the high-expectations that I have for Brody Pennell. They were both super friendly and through. They covered all of the expected work and also looked into another issue I was having. They were both able to provide solid advice on how to proceed.From a business standpoint, the scheduling, confirmation, and information regarding the visit was top notch. I felt informed every step of the way and the information was accurate.%%%%%%%%%%%%%%%%%%%%%%%%Review from 2023:This review is specific to the HVAC maintenance repair completed this spring. I setup the appoint and received confirmation and a reminder the day before. Once the technician was assigned, I received additional communication that they were on their way.Jose C. arrived and was prompt, courteous and professional. He chatted with us first to talk through what he was going to do, got a lay of the land and then went to work. He took time once he was completed to share his findings, the work he did and discuss next steps. He captured photos of the before and after and documented his work well.He also took the time to call dispatch/office to clarify some confusion, which was great. All in all, great experience from start to finish.
karen S.
1711564697
Juan Molina, Mike Stafford, and Richie Salazar were exceedingly knowledgeable and efficient in servicing our HVAC. They used shoe covers and drop cloths so our condo was clean when they left!
Eliette K.
1711564203
Daniel and Pablo did a great job with the HVAC maintenance.
Nathalie K.
1711562137
James & Alberto were very courteous & thorough. Thank youNicole Karsenty Ligeti
Obele A.
1711555122
René and Leo Morales were fantastic! Very personable. Excellent customer service. They took the time to explain the situation and options for how to proceed. Stamp of approval granted.
Christopher F.
1711521527
Daniel Avila and Pablo Lopez provided very friendly and efficient service.
Kathy I
1711516687
I had to take the time to update my review and thank and compliment Ashton K. and his team of installers Mike, Raul, Elario, and Juan DS who installed our new furnace. Ashton’s knowledge and follow up has been fantastic. The installers workmanship was excellent. They were all professional and respectful and kept our home neat and clean after they finished the installation. The furnace is working perfectly. Our follow up appointments with Jose Rivera, Jonathan A. and Ramiro S. were also handled with the same professionalism.I would highly recommend Brody Pennell. The quality of their furnaces and workmanship are excellent.Juan Molina and Ashton K provided me with great service today. They were both very thorough and detailed in explaining the technical problems that were occurring with my heater. I was very pleased with their high level of service and professionalism.
Jenny W.
1711509954
Today when we had someone come to look at our ancient HVAC, I never imagined that we could be shown in great detail the inner workings of the thing. David Mars with his kit of diagnostic tools and his supervisor Fabio Lopez (I think is Lopez) showed us in photos and videos (even with a tiny camera on a gooseneck that showed inaccessible parts) and explained at length the significance of all the horrors we were looking at. We are now scheduled for installation of a new HVAC tomorrow. I’ll post again if my experience changes but so far we are impressed.
Susan A.
1711495997
Daniel B and Alessandro A were fantastic today! They did a great job doing the maintenance on my system and were just lovely to work with. Great job!
ROSALINDA M.
1711490429
As always Juan Molina provides exceptional service with thorough expertise and the most pleasant and courteous manner. He is. A credit to the BP brand of excellence in service.
Mike B.
1711477483
Timmothy was the best tech that ever came to service my system. He was friendly and thorough and went above and beyond to make sure the job was done to my satisfaction
Lori P.
1711433844
Cristina P.
1711418295
Juan Molinas and Dave ocampo came to my condo for my air maintenance. I’m so impressed with their politeness, care and knowledge. They went above and beyond my expectations. I highly recommend Brody Pennell.
R A
1711416532
I really enjoy the service guys here. David and Alex were really lovely and the last time Benny was so great. I was already planning on getting a new unit. Wasn’t a huge fan of the particular supervisor I dealt with in terms of sales, but we were able to finalize with Michael and I would like to believe we all have bad days. Michael made us feel much more confident. I will update when I have my new system. I do always appreciate that they are very respectful and adaptive to my medical needs.
Bill C.
1711410254
Kevin and Robert Jadds showed up the same day, went underneath the house, and couldn't have been more pleasant and professional. I have signed up to use Brody for all my HVac needs going forward.
Steve B.
1711405223
Spencer, Mike and Ariel all were exemplarySpencer smartly contacted Mike to ascertain the full parameters of our problem and while waiting initiated with Ariel our condenser maintenance. And Mike presented us with options that satisfied our needs. Great team
Arik M.
1711404349
Timothy and Juan D. Did an excellent job cleaning my mini-split unit indoor and outdoor.
Maria T.
1711401681
Anthony Manzo David EThey did a great job trying to figure out how to fix. Great job guys!
cynthia C.
1711397456
Timothy TranJuan Dejesus
CRMCSYS
1711393886
Marco Ayala (technician), Juan U. (apprentice) and their supervisor Ashton were courteous, patient and thorough. They reviewed the problems I have with my Carrier unit and explained why I needed it replaced. I was given the choice of 3 new models with price and labor for each. They offered to contact my HOA’s management company for the roof installation and will arrange a city inspection after the work is completed. I would not hesitate recommending Brody Pennell to family and friends.
Kerrie K.
1711390619
Benny was thorough in his inspection, and he went over and above in answering my questions and giving me sound advice. His patience and professionalism are so rare these days. Thank You
Dylan L.
1711387435
Timothy Tran and Juan D. were exceptional!!!
Joe B.
1711226631
Excellent work!! Very cordial and informative. Super attentive. Right on time. All great.
Kimberly B.
1711222248
Wanted to give a big thanks to Mike, Raul, Rosendo & Nathan from Brody Pennell Plumbing & Heating for the installation of our new HVAC system, the professionalism of the guys & quality of the installation was top notch!!!
Isabel W.
1711145412
Juan Molina and Freddy did a great job! Very clean and very respectful :)
Dagoberto V.
1711141678
Great guys both Juan and Tony hope to see them next service stay safe ., great to deal with and very good knowledge
David O.
1711136928
3/22 - clean, fast, courteous job with Troy and Phil. Very polite and thorough! Another fantastic job by the people at BrodyYet another pleasant service experience with Marcos!!! Also told me about an air scrubber install that Brody can do as well.10/9: another great job by Steven
Diane S.
1711134416
M H.
1711131246
Today Armando and Jadds provided the professional technical service that Brody Pennell has always delivered for years.Our A/C / Heating system is getting older, but the excellent routine maintenance and advice Brody Pennell has given me keeps everything running smoothly.
Khemsuay P.
1711129519
03.22.2024Juan Molina and Freddy are very god at what they do, freindly and knowledgeable.I really recommend them .Enmity is the best !!I really recommend him
Deke S.
1711126198
Rene & Leo. On time. Friendly. Respectful. A+++
Mario Sanz S.
1711125163
Very easy to connect and schedule an appointment for my heater maintenance.Maria was on time, very knowledgeable, friendly, and attentive to all my questions, providing clear responses to each.
Mo S
1711059929
Timothy and Mike provided one of the best customer experiences I ever had! Their kindness, thoroughness, knowledge, and expertise were top notch! They went beyond the call of duty and helped us tremendously! Thank you immensely!!
Ellen C.
1711057975
Rene and Leo were very kind and efficient!
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