< Previous30 FEBRUARY 2019HIGH-PERFORMANCE HVAC TODAYHVAC SYSTEM VARIATIONSStarting at conception, i.e. construction, the HVAC system’s genetics are affected by many of the same factors as the building envelope. Differ-ent crews and skill levels produce diffrent results. How hot was the attic or roof during installation?The duct system may have some unique vari-ables like how well joints were sealed, and how tight the flex was stretched in the attic or drop ceiling. Was enough support provided on turns? Was a flex duct running horizontally to a straight boot radius and supported properly? Add in little or no air balancing and improp-er refrigerant charge, and the system’s fate is locked in. After construction, we have similar variables to the building issues: The cable or alarm guy dis-connects a flex run; They cut into returns to use them as wiring chases. Homeowners seal off reg-isters and close dampers. Is it any wonder why each home or building is like a fingerprint, or has its own DNA string of ge-netic instructions?THE SOLUTIONThere really is only one way to identify these mutations and defects so they can be corrected. A doctor uses testing to determine predispo-sition for, and diagnoses of diabetes, cancers, abnormal organ formations, heart disease, etc. As an HVAC professional, you must have the right tools and know-how to test your patients thoroughly. You must understand when to ap-ply which testing and when, as you investi-gate the causes of defects so you can offer real solutions. The good news is today we have the best test instruments on the market. We also have the best training ever to help make this level of testing a reality. This lets you offer cost effective solutions for your customers. After all, If You Don’t Mea-sure, You’re Just Guessing!™ Did you know that two identical homes or buildings in the same exact area can have very different characteristics? In fact, even if they were built at the same time with the same specifications, you could say each building has the equivalent of its own DNA.The most obvious causes include orientation of the building, natural shading, etc. Other differ-ences include more subtle, yet significant changes that occur both during construction and once oc-cupied. Here are some less apparent factors that can contribute to a building’s unique DNA:BUILDING CONSTRUCTION VARIATIONSWhile the same components may be used on two identical structures, each building’s charac-teristics can be changed by how those compo-nents are installed. For example, is the insulation in walls and un-conditioned spaces installed properly? Are there gaps and voids in the insulation and sheath-ing? Was it over-compressed in some cavities? Was blown in insulation applied at a consistent height? Were all penetrations sealed properly? Then add in variables including skill differenc-es from crew to crew, how late they were on com-pleting the job, uncomfortable attic and crawl space temperatures -- and the unique DNA be-gins to form before the building is even finished. Once a building becomes occupied, other subtle changes happen to its makeup. Unre-lated work is performed that affects envelope and insulation integrity. The cable or alarm guy disturbs the insulation in the attic, kitchen and bath fans are upgraded, changing building pressures, and so forth. Then there are the changes made by home-owners with how they use rooms, including blocking off unused rooms, remodeling work, fireplace add-ins, and more. Thus the building’s DNA continues to mutate and evolve – or more likely - devolve.Dominick Guarino is publisher of HVAC Today magazine and CEO of National Comfort Institute, Inc. He can be reached at domg@ncihvac.com ONE MORE THING...By Dominick GuarinoEvery Building Has a Unique DNANext >