The Second Step – Select Efficient and Properly Sized Heating and Cooling Equipment using ACCA Manual S Equipment Selection

So you are getting ready to replace an old HVAC system or perhaps you are building your new dream home.  Before making that purchase or even selecting the installing contractor, there are three important factors to investigate to ensure optimum comfort in your home for many years to come.  This blog addresses the 2nd step – ACCA Manual S HVAC Equipment Sizing

EnergyStar, LEED, CALGreen, and many permit offices further require that once an HVAC designer has applied ACCA Manual J to determine the heating and cooling needs of the home, then the

ACCA Manual S Equipment Selection

ACCA Manual S HVAC equipment sizing procedures

designer needs to ensure the physical equipment being installed is a proper fit by utilizing ACCA Manual S HVAC equipment sizing.

Why do EnergyStar, LEED, CALGreen, and many permit offices insist on Manual S sizing for your heating and cooling equipment?  Because Manual S equipment selection procedures have a proven track record over many decades just like the Manual J.  If your HVAC designer uses proper equipment selection techniques:

  • A/C or heatpump? If heatpump, electric strip backup or furnace in winter?
  • Proper SEER energy rating, minimum 13 SEER
    • SEER = Seasonal Energy Efficiency Ratio
    • Proper sizing is more critical than SEER
    • What is the recommended CFM and static pressure based on OEM performance data?
      • OEM – Original Equipment Manufacturer
      • Must be collected by and selected by the installing contractor and supplied to the HVAC designer
      • Does sizing fall within EnergyStar Standards?
        • AC cooling equipment should be sized at 95-115% of Design Total Heat Gain, or the next nominal size that is available to satisfy the latent and sensible requirements.
        • Heat pump cooling equipment should be sized at 100-140% of Design Total Heat Gain, or the next nominal size that is available to satisfy the latent and sensible requirements unless a larger size is dictated by the heating equipment selection.
        • Listed Output Heat Capacity must be sized at 100-140% of Design Total Heat Loss, or next nominal size unless a larger size is dictated by the cooling equipment selection.

An oversized unit cycles on and off continuously resulting in increased utility bills and wear and tear. Heating and cooling equipment based on properly sized equipment will run better which will save both money and energy!

Also Read: The First Step -Make Sure Your HVAC System is Sized Correctly using ACCA Manual J Load Calculations

Also Read: The Third Step – Size Supply & Return Duct Work Properly Using ACCA Manual D Duct Design