HVAC Design Protocols

There is a lot more that goes into the HVAC design process than one may think. When it comes to proper HVAC installation for a home, there are certain protocols listed in ACCA’s HVAC technical manuals that should be followed. These HVAC design manuals provide guidance for the load calculation, sizing, air distribution and duct design processes.

You can find the description of each manual below:


Manual J : Load Calculations

HVAC Design - Manual J

Manual J outlines the requirements that are needed when conducting a residential load calculation. Load calculations help to determine how much heat a house gains during the summer and how much it loses during the winter, taking into consideration various factors (types/colors of roofing, insulation values, etc.), which makes it easier to figure out how much heating or cooling a room needs.

To learn more about Manual J, watch the video linked here.


Manual S: Sizing & Selection

HVAC Design - Manual S

Manual S is used to help select the proper heating and cooling equipment, whether it be an air conditioner, boiler, furnace, etc., that is needed for a home once the load calculation (manual J) stage has been completed. It contains information on equipment sizing, airflow, ventilation, as well as sizing requirements for 11 types of heating and cooling equipment. When it comes to forced-air cooling systems, this selection process can be critical because of the different characteristics (sensible and latent capacities, static pressure delivered, etc.) involved with each piece of equipment.


Manual T: Air Distribution

HVAC Design - Manual T

Manual T focuses on the HVAC’s air distribution. It shows you how avoid drafts and stagnant air problems that are caused by wrong equipment selection and sizing. It also gives step-by-step guidance on how to size, locate and select grilles and registers, return grilles, and supply air diffusers.

In this manual, the following questions are answered: Where will the diffusers, grilles, supply and return registers go? What kind of grill, diffuser, or vent will be implemented?


Manual D: Duct Design

HVAC Design - Manual D

Finally, Manual D provides guidance on how to design the duct system, once the load calculation (manual J), proper equipment (manual S) and air distribution (manual T) have been determined. It focuses on how to determine the best duct design for the space that is available. It also includes information on how to properly size, insulate and seal air ducts.

To learn more about Manual D, watch the video linked here.

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