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Load Calculations & Mechanical Design The overwhelming majority of heating, ventilation, and air-conditioning (HVAC) systems are not actually designed, but are instead installed using the installer's "best-guess" method. It's no surprise that the average installed efficiency of a residential HVAC system is a mere 60%. The most common complaints we hear from those living in exising homes are related to comfort, air-quality, and efficiency. Here's the top-ten list:
Starting with proper sizing of the mechanical systems, we carefully design a system that satisfies the heating/cooling needs of the structure, the air-quality needs of the occupants, and the financial needs of the budget. From traditional heat pumps, to furnaces, to geothermal systems, we'll make sure your system is designed properly and the details communicated clearly to the installation contractor. |
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Avoiding these performance issues is easy when the system is designed properly AND the system is installed according to the design. By deciding upfront on the type of system, size of the system, placement of registers, and the size of each duct, the guesswork is eliminated and the installers have an excellent road-map to guide the installation process.
What is a Manual J?
Manual J is the name for a specific protocol used to determine how much heating / cooling a home needs to stay cool and dry in the summer and warm in the winter. This process was developed by engineers in the heating and air conditioning industry and has been used for decades to accurately size heating and air-conditioning equipment.
What is a Manual D?
Manual D is the name for the protocol used to design the ductwork for a heating and air-conditioning system. Completing a Manual D is the best way to ensure that a heating and air system will deliver maximum comfort at peak efficiency. This protocol, like the Manual J, was developed by members of the ACCA (Air-Conditioning Contractors of America) contractors association, and engineers at ASHRAE (American Society of Heating, Refrigeration, and Air-Conditioning Engineers).
Why Size and Design?
The Manual J and Manual D protocols are specifically listed as code requirements for every major residential building code used in the United States, including the 2003, 2006, and 2009 IRC and IECC. However, the most important reason to perform proper sizing and design calculations before beginning a heating and air project is to ensure that a home will be a healthy and comfortable place to live. Here are some characteristics associated with properly designed systems vs. improperly designed systems:
Who Should Be Responsible for Size and Design Calculations?
Although Manual J and Manual D calculations are specifically required by building code, code officials DO NOT ask for or review this information. In fact, field studies have shown that proper design calculations are rarely completed by heating and air contractors. Consequently, heating and air systems are frequently over sized and ductwork is commonly undersized. Homeowners, builders, and architects should contract with a qualified third party (that's us) to ensure these calculations are properly completed.
Contact us to request a Manual-J calculation for your home or building.
