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Manual J Load Calculation & Manual D Duct Design

Whether your company needs a residential Manual J load calculation to meet your local municipality's building permit submittal requirements or to ensure you’re sizing the heating and cooling system accurately for your client, Enser Consulting can meet your Manual J, Manual S and Manual D needs and exceed your expectations.

Why use Enser Consulting for your Manual J and Manual D needs:

  • Licensed Colorado Professional Engineer performs all Manual J load calculations, Manual S equipment selection and Manual D duct design. Only State Licensed Professional Mechanical Engineers have demonstrated their proficiency, experience and expertise in Mechanical Engineering through state testing & licensure.
  • Design experience includes thousands of homes (and satisfied clients!) throughout the country.
  • Experience with all building departments in Colorado and many throughout the country to ensure your submittal process goes smoothly to avoid unnecessary delays that cost you time and money
  • In addition, we are fully insured with General Liability and Professional Liability Insurance (Errors & Omissions).

Benefits of Residential Manual J load calculations and Manual D duct design include:

  • Detailed and accurate room-by-room load calculation
    • Avoid oversizing your equipment
    • Ensure proper airflow to each room to avoid hot/cold rooms
    • Actual insulation R-values, window U-values and other envelope information will be used in your load calculation
  • Reports certified by ACCA to meet all requirements of Manual J, 8th Edition
  • Wrightsoft Manual J & D reports are accepted by:
    • Local Colorado and national building departments for building permits
    • Energy Star, LEED & green building projects
  • Duct sizing with Manual D service
    • 2 - Line Ductwork
    • Ducts configured to meet your needs - Rectangular trunks, round branches, flex branches, joist space returns, etc.
    • Duct layer can be written to AutoCAD files
  • Manual S equipment selection
    • Your preferred equipment can be selected
  • Duct system parts pull order reports available
    • Know exactly what duct sizes, duct lengths and duct fittings you will need to construct the system in the field
  • Satisfied homeowners with properly sized equipment and lower utility bills

Why Size A Heating & Cooling System?


The most common mistake made in sizing a residential heating and cooling system is oversizing. Issues with an oversized heating and cooling system include:

  1. Higher initial upfront cost of the heating and cooling equipment
  2. Inefficient operation yielding higher operation costs and equipment breaking down more often
  3. Oversized air conditioners do not operate long enough to dehumidify the air, which results in moist air and possible mold growth
  4. Oversized furnaces create large temperature swings in the home

Using a "rule of thumb" estimate based on the square footage of the home without taking into account the construction of the home and other factors can lead to an oversized system.

Correctly Sizing a Heating & Cooling System

A correctly sized heating and cooling system will be sized using the Manual J load calculation procedure. The Manual J load calculation procedure takes into account the following items:

  • Local climate and actual orientation of the home
  • Insulation R-values
  • Roof and attic construction
  • Wall and floor construction
  • Basement and crawlspace construction
  • Window U-values, shading, insect screens & overhangs
  • Door U-values
  • Tightness of construction and infiltration
  • Number of occupants
  • Major appliances
  • Several other factors

For new homes, the Manual D duct design procedure should be followed to properly size the ducts to ensure proper airflow to each room. The Manual J load calculation procedure sizes each individual room instead of sizing the home as a whole to ensure that each room receives the proper airflow. Without a properly sized duct system, there may be issues with the airflow resulting in hot or cold rooms. New heating and cooling equipment should be selected following the Manual S equipment selection procedure to ensure that the equipment is properly selected for the home.

Even if your heating & cooling contractor or home builder is not required by your local building department to perform a load calculation on your new or existing home, home buyers and home owners should insist that a Manual J load calculation be performed for the reasons above. Heating & cooling contractors and builders should have the Manual J, D and S procedures performed to ensure that they are sizing the heating and cooling system correctly and offering the best possible product/service to their clients.

Please contact us today with any questions.


Enser Consulting, LLC
(303) 725-8836
Serving Arizona, Colorado & beyond

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