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  • Writer's pictureManny J

Manual D & S 101

If the Manual J, D, & S got ya scratching your head, don't worry, you're not alone. These reports are essential for anyone involved in the HVAC industry, whether you're installing a new system or remodeling your home. Once you understand what these reports are and why you need them, you'll wonder how we've ever got by without them.

(We started on the Manual J in our first blog "Manual J 101" so give that a quick read if you haven't yet.)

In this blog, we'll take a quick look at Manual D and S reports. Let's see if we can explain what the heck these are in under five minutes.

I enjoyed breaking the Manual J down two ways: 'The Slightly Nerdy Explanation' and 'The Michael Scott "Why don't you explain it to me like I am five years old?' explanation. So lets do the same for the Man D & S.

What is the Manual D?

The Slightly Nerdy Explanation:

The ACCA Manual D is all about duct design. This report provides precise calculations for duct sizing and layout to ensure that the airflow throughout the HVAC system is efficient and effective. HVAC professionals use Manual D to avoid common problems that can arise from improper ductwork design, such as uneven airflow, high static pressure, and excessive noise. Proper duct design that Manual D provides can lead to increased energy efficiency, improved indoor air quality, and a longer lifespan for HVAC systems.

The Michael Scott "Why don't you explain it to me like I am five years old?" explanation:

Manual D is about designing ducts. It calculates how big the ducts should be and how they should be laid out. This helps the HVAC system work better and stay quiet. It also makes it use less energy and last longer.

What is the Manual S?


The ACCA Manual S is a comprehensive report utilized for selecting suitable HVAC equipment for residential purposes. This report meticulously evaluates the cooling and heating requirements of your home, matching them with appropriate HVAC units. Factors like unit size and energy efficiency rating are carefully considered to ensure a perfect fit for your home. While clients have the liberty to choose their desired brand, the manual S ultimately determines the specific model of HVAC equipment to be installed. The outcome of the manual S is the actual Model # of the HVAC equipment to be installed.

Michael Scott:

The Manual S is a report that helps you choose the right air conditioning and heating equipment for your home. It looks at factors like the size of the unit and how much energy it uses to make sure that it is perfect for where you live. You can choose which brand you want, but the manual S will tell you what model number should be installed.

Now ya know

The Manual D & S are not required by the building departments as often as the Manual J, but for the best HVAC install getting all three is the way to go. Unless you are only installing a Mini-split Ductless system, which in that case you will only need the J & S (Do I need to explain why?)

I like the theme of simplifying things so we can all understand what's going on, let me know what to do next!

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