Things HVAC contractors should know before installing a new system in California (to pass the 2013 energy code)

I keep running into HVAC contractors still unfamiliar with HERS duct leakage tests, total airflow and fan/watt draw tests to pass in the 2013 California Energy Code. This is from the BECT.US website for all to see but I keep having to explain it while a distraught contractor, technician or homeowner asks what is wrong. 

Important Items for Installing HVAC contractors to know:

Please note: The 2013 energy code, Title 24, requires quite a few things in an HVAC system. Here are some highlights.

• HVAC system sizing must be calculated by an approved method. Duct systems are required to be designed by an approved method. ACCA Manual J and Manual D are one system to do this. Wrightsoft is the leading software tool. “Rules of thumb” sizing do not pass code or work well. I know one contractor who was sued for using them rather than a code approved method
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• Air conditioners need to have at least 350 CFM per ton of air flow. A/Cs need to use 0.58 or fewer watts per cubic feet of air flow. This is the code absolute minimum. Here, more airflow is better.
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• You’ll need to have the cold air return properly sized. See above. Again, Bigger = better. I keep running into contractors with wildly oversized furnaces and air conditioners who balk at the idea of using anything larger than a 16" return duct or that two large returns might be better than one small one. 
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• You’ll need to state the airflow the filter system is rated for. The registry will want to see .05 inches of water column of pressure in the return and .10 in the supply. Are you sure the return grill from 1955 (heat only) is big enough for the new system (with AC) in 2016?
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• You’ll need to tape the sheet metal boots to the drywall or flooring. Use UL 181 aluminum tape.
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• You’ll need to mastic over the tape that is sealing your system. Really, yes.
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• Use only “UL181” approved plastic and metal tape and mastic. UL 181 is code required.
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• You’ll need to have less than 6% duct leakage in new duct systems and less than 15% in existing systems. (FYI: Hot rodder contractors get their systems below 1 percent.)
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• (Note: the secret ingredient here is air duct mastic. Use it liberally. Put it on every connection. It is cheaper than having to pay a HERS Rater to come back and retest the system.).

 Missing any of these items is a failure, so take heed.

It gives me such joy to see a system that holds air when I set-up the duct test equipment. I hope that you enjoy it as well.

George Matthews
Building Energy Compliance Testing