#Manual J

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 […]

Every piece of air conditioning equipment can move a certain amount of heat BTUs (British Thermal Units) at set conditions. In most cases, during the cooling mode, a portion of those BTUs will go toward changing the temperature of the air, and a part will go toward changing vapor water in the air into water […]

How an A/C System got to be Oversized (Maybe) But My Old Unit Worked Fine?! Most of us have heard this at some point. This complaint typically comes from a particularly unhappy customer after the installation of a brand new A/C system. Throughout this article, we’re going to explore the possible root causes of this […]

This article was written by HVAC contractor and Building Science Whiz, Michael Housh. Thanks, Michael! For a while, I’ve fallen into this camp where I feel Manual J overshoots heating loads. First off, I would like to say that Manual J is only as good as the information you give it, but we often run […]

Fenestration is a fancy architectural term that means “openings in the outside of the building.” You will see this word a lot when you read ACCA manual J or when you are doing a manual J load calculation. Fenestration loads include heat losses and gain through windows, doors, skylights, etc., and they can make up […]