Manual J

There are three types of floors: slab-on-grade, crawlspace, and basement. It should be fairly obvious when you are collecting field data as to what type of floor you are working with. Here is a brief overview of how each type affects a load calculation. Much of the information for this article comes from Allison Bailes’s […]

This article will cover how to collect field data for walls on an existing home for an ACCA Manual J calculation. In full disclosure, I had never collected any field data for a Manual J before I wrote this article. Many of the methods discussed were suggested by HVAC technicians and contractors in an online […]

Starting to work on a Manual J load calculation can feel extremely overwhelming. How do we know what to focus on? What does normal look like? What if I’m way off on something and install way too big or small of a unit? On a practical level, what is the payback or value of spending […]

Have you ever been tasked with installing the exhaust duct for a kitchen hood?  I have, and when doing so, I wondered how to size the duct run correctly. Since I had a basic understanding of how airflow works, I knew that there had to be a limit on the resistance the fan can handle; […]

Bryan recently released a podcast on rules of thumb and how they can really get us in a pickle with sizing ductwork. With that in mind, I thought this might be a good time to do a walkthrough of Manual D from start to finish on a project I just finished up. My good friend […]

This tech tip was a collaborative effort between Matt Bruner, Adam Mufich, Ed Janowiak, and Genry Garcia. Thank you to everybody who gave their input! The next time you come across a homeowner who wants a bigger HVAC system, or you simply want to set expectations for a customer, share this tech tip with them. […]

I get questions all the time about performing “load calculations” and “rules of thumb” or how to do it properly. This article isn't about load calculation, but the only good answer is to find a quality ACCA-approved Manual J software and get used to using it. You may have heard from others in the field […]

This article was written by Genry Garcia of Comfort Dynamics, Inc. Thanks, Genry! This is a piece about oversized air conditioners. Though the symptoms and consequences of oversized heating equipment are similar to those of air conditioners, you’ll notice that the focus throughout the article will be on the cooling side—specifically from the perspective of […]

Every year when outdoor temperatures rise, there is a rash of news stories and articles about air conditioning. We had an early heatwave this year, and many people have come out and referred to the idea of a rule of thumb of what temperature you can achieve indoors based on the outdoor temperature; most commonly […]