Don't Fear the ACCA Compliant Manual J Load Calculation Process - Becoming Familiar with Manual J

The well known organization, ACCA (Air Conditioning Contractors of America), has drafted the Manual J8 Residential Load Calculation, a proven procedure to accurately calculate the correct size of a HVAC system for a residential home. By utilizing the ACCA compliant Manual J Load Calculation you set yourself apart from your competition by assuring your client will have the industry benchmark in home heating and cooling efficiency, ultimately reducing their energy costs. It is extremely important to size the heating and cooling unit appropriately. If the system is too small, it will not condition the house quickly enough resulting in the heating and air conditioning equipment to run continuously trying to reach the desired setpoint. The under-sized and over-worked equipment will not last as long as an appropriately sized system. Although, on the other hand, if the system is over-sized, it will condition the residence too fast without being able to fully dehumidify select rooms in the house. This issue is commonly referred to as "short cycling." Contractors often use "rule-of-thumb" to figure out the size of heating and cooling systems, without considering some key variables such as, internal heat gain and loss, moisture content, orientation of the house, ventilation and infiltration resulting in an over-sized heating and cooling system.

It is less costly to size a heating and air conditioning system according to the average winter and summer climate conditions when deciding the outdoor design temperature, instead of prepping for the rare "worst-case-scenarios." ResidentialManual J8 calculations are not applicable for high rise, commercial and industrial buildings, a room with an indoor hot tub or swimming pool, and houses that utilize passive solar layouts.

In any ACCA Compliant Manual J load calculation, the following items need to be addressed: • Use the actual building orientation. Solar heat gain in certain rooms of the house depends on the orientation. • Acquire the exact construction material R-values • Properly evaluate the infiltration load and required ventilation load following Manual J procedures. • Use design conditions approved by ASHRAE or Manual J. According to ACCA, the indoor dry bulb temperature should be 70oF for heating and 75oF for cooling. The indoor relative humidity (RH) for cooling should be 50% for wet climates and 45% for dry climates. • Include overhangs - "By including the overhang benefit in the analysis, the projected cooling load can be reduced to a ton on a 2400 ft2 home" (Addendum A to ACCA Manual J). • Include the people internal gain from a house, which is assumed to be the number of bedrooms plus one.

Contractors can save huge amounts of money preventing costly mistakes when installing heating and cooling systems in a residence by employing an Experienced Provider to do the calculations. There are so many significant benefits to the client in hiring an ACCA Compliant Manual J Load specialist: HVAC design experience, ACCA certified software experience, quick and precise turnaround time, and customer service. WrightSoft Universal 12.0 software is one of the most recognized Load Calculation software programs for EnergyStar, building permit code compliance, LEED Certification, Build Green projects and energy-efficient mortgages.

Make sure your HVAC installer or Manual J Load Calculation provider is not using an inferior, non-ACCA certified software to create your residential Manual J report or it could be declined.

The Air Conditioning Contractors of America (ACCA) Manual J Residential Load Calculation Procedure is the approved industry standard for the proper sizing and selection of HVAC equipment for residential applications. Manual J outlines the accurate procedure which can be used to establish the heat loss and heat gain for conventional residential structures. Make sure your Load Calculation Reports are based on ACCA's Manual J 8th Edition, inclusive of all four addenda to the 8th edition.

Lastly, a great deal of money can be saved in using an ACCA Compliant Manual J Load Calculations provider for every home you decide to build by choosing the right sized HVAC system. An ACCA Compliant Manual J Load Calculation provider can help set you apart from your rivals by assuring your client will have the industry standard in home heating and air conditioning efficiency,ultimately {keeping their costs and yours to a minimum

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