Load Calculations — A Small Investment With Big Returns

When you’re upgrading your home’s cooling or heating system, or buying an HVAC system for a new home, your HVAC technician should use cooling and heating load calculations to determine the correct size equipment for your home, as well as to make sure the home’s ductwork is compatible with your new system.

The information gleaned from a load calculation allows the technician to install a system that uses the least Load Calculations -- A Small Investment With Big Returnsamount of energy to provide maximum home comfort. For homeowners, an appropriately sized system, and an efficient duct design, yields energy savings, enhances room-to-room comfort, and improves indoor air quality.

Modern residential load calculations employ Manuals J and D, developed by the Air Conditioning Contractors of America (ACCA). Originally, they were worksheets requiring manual data entry and calculations. Now, these manuals are available via software programs, further increasing accuracy. Manuals J and D use precise formulas based on various aspects of your home design.

Manual J is used for two different types of information:

  • Whole-house (bulk) HVAC load calculations
  • Room-by-room load calculations

Together, these calculations will determine the correct equipment size for your home. Factors considered by Manual J include:

  • Home size and orientation
  • Climate
  • Home layout and number of floors
  • Insulation quantity and quality
  • Window specifications
  • Rates of air leakage
  • Appliances and lighting fixtures (interior heat-generators)

Once the applicable information has been entered and calculated, your HVAC contractor will have the information he needs to discuss equipment options with you.

Manual D. This manual is used, in conjunction with Manual J’s load calculations, to design and size ductwork. If you invest in a high-quality A/C, but don’t address issues in your duct design, you will have wasted your money. Your system is only as efficient as the ducts that deliver the air. It’s worth it to make necessary ductwork modifications to maximize system efficiency.

If you would like to discuss an HVAC upgrade for your Cleveland area home, please contact us at Geisel Heating, Air Conditioning & Plumbing. We’ve provided quality service to Northeast Ohio residents for 75-plus years.

Our goal is to help educate our customers in Cleveland, Ohio about energy and home comfort issues (specific to HVAC systems).  For more information about load calculations and other HVAC topics, download our free Home Comfort Resource guide.

For those Do it Yourselfers who would rather take control of your own indoor comfort, you can shop our online store for replacement parts, products and accessories!

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