ACCA Compliant Manual J8 Load Calculations Are Simple to Do and Often Free - In What Universe?
ACCA (the Air Conditioning Contractors of America) publish Manual J and Manual D worksheets and HVAC contractors used these forms to calculate residential heat loss and heat gain because they were the common way for calculating residential heat and cooling loads} for decades.
Times have changed and Manual J and Manual D calculations are no longer calculated on pencil and paper; contractors now use fancy software programs. Beware - the software programs must be ACCA certified or your buildin permit office will reject the calculation. The only ACCA certified Manual J programs are WrightSoft Right-J8, Elite RHVAC, EnergyGauge, Adtek and AccuLoads. All the developers claim to "save time and increase your results with this easy to use load calculation tool".
There are those who claim that the software removes the complexity because the HVAC contractor never has to understand any math equations. Just take software out of the box and use. We at Savoy Engineering Group have seen hundreds of inaccurate and flawed designs by people who do not understand Manual J, S & D theory. It is similar to the student who never understood simple math and now needs a calculator - they do not understand when the outcome doesn't make logical sense.
The user of the software must understand how each parameter changes the Manual J8 heat loss and heat gain results. What happens if I build the identical house in different climates? What if the building direction orientation changes? What about the insulation values of the wall and roof? And then there are windows - size, orientation, type, glazing, SHGC. And let us not forget about people and appliances. All of these determinants and many more MUST be accurately entered into the ACCA certified Manual J software program. Otherwise, it's garbage in, garbage out.
Most residential codes and permit offices are now insisting upon Manual J8 load calculations, Manual S HVAC equipment sizing and Manual D duct designs. For example, the 2012 International Residential Code Section M1401.3 requires that "Heating and cooling equipment and appliances shall be sized in accordance with ACCA Manual S based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies."
While, IRC section M1601.1 requires that "Duct systems serving heating, cooling and ventilation equipment shall be installed in accordance with the provisions of this section and ACCA Manual D or other approved methods."
But then the government (US Department of Energy) puts on their website, "Homeowners should insist that HVAC contractors use a correct sizing calculation before signing a contract. This J load calculation service is often offered at little or no cost to homeowners by €¦ conscientious HVAC contractors." What contractor has hours of free time to calculate a Manual J8 load calculation to every person who is also collecting 5 other quotes from contractors?
So it is obvious the licensing code is just going to get stricter. Make certain you select a Manual J & D provider who understands what they are doing, not just winging it. Also look for a designer that has easy to understand pricing, not "$149 + $0.12 per sq ft up to 3,000 sq foot, then an additional fee for€¦." - you need an accountant to figure out your price. We offer FAST, ACCURATE & AFFORDABLE engineering services for all your Manual J8, S & D needs!
Times have changed and Manual J and Manual D calculations are no longer calculated on pencil and paper; contractors now use fancy software programs. Beware - the software programs must be ACCA certified or your buildin permit office will reject the calculation. The only ACCA certified Manual J programs are WrightSoft Right-J8, Elite RHVAC, EnergyGauge, Adtek and AccuLoads. All the developers claim to "save time and increase your results with this easy to use load calculation tool".
There are those who claim that the software removes the complexity because the HVAC contractor never has to understand any math equations. Just take software out of the box and use. We at Savoy Engineering Group have seen hundreds of inaccurate and flawed designs by people who do not understand Manual J, S & D theory. It is similar to the student who never understood simple math and now needs a calculator - they do not understand when the outcome doesn't make logical sense.
The user of the software must understand how each parameter changes the Manual J8 heat loss and heat gain results. What happens if I build the identical house in different climates? What if the building direction orientation changes? What about the insulation values of the wall and roof? And then there are windows - size, orientation, type, glazing, SHGC. And let us not forget about people and appliances. All of these determinants and many more MUST be accurately entered into the ACCA certified Manual J software program. Otherwise, it's garbage in, garbage out.
Most residential codes and permit offices are now insisting upon Manual J8 load calculations, Manual S HVAC equipment sizing and Manual D duct designs. For example, the 2012 International Residential Code Section M1401.3 requires that "Heating and cooling equipment and appliances shall be sized in accordance with ACCA Manual S based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies."
While, IRC section M1601.1 requires that "Duct systems serving heating, cooling and ventilation equipment shall be installed in accordance with the provisions of this section and ACCA Manual D or other approved methods."
But then the government (US Department of Energy) puts on their website, "Homeowners should insist that HVAC contractors use a correct sizing calculation before signing a contract. This J load calculation service is often offered at little or no cost to homeowners by €¦ conscientious HVAC contractors." What contractor has hours of free time to calculate a Manual J8 load calculation to every person who is also collecting 5 other quotes from contractors?
So it is obvious the licensing code is just going to get stricter. Make certain you select a Manual J & D provider who understands what they are doing, not just winging it. Also look for a designer that has easy to understand pricing, not "$149 + $0.12 per sq ft up to 3,000 sq foot, then an additional fee for€¦." - you need an accountant to figure out your price. We offer FAST, ACCURATE & AFFORDABLE engineering services for all your Manual J8, S & D needs!
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