Arkansas HVACR NewsMagazine March 2019

S tate, National, Chapter News Tech News

motors. Timed on and off fan operation (for harvesting evaporator energy) was left at factory defaults. There were incorrect fan settings on variable capacity equipment. Thermostats for high end equipment were left at default programs in selectable fields. The opportunity for improvement should be given the homeowner. Failure to inform homeowners only perpetuates problems in the HVAC industry. Several studies across the country have proven 80% or more of cooling systems are oversized in a cooling climate and they deliver only 60% of rated capacity. The homes tested proved the same is true in central Texas. Shouldn’t the contracting community propose lasting improvements? There are methods to identify the issues quickly that tell a contractor a particular home is a candidate for duct system redesign. Static Pressure Monitoring- We should begin taking static pressure upon arrival at a residence. Size up the system prior to proposing repairs-

This practice should take precedence over hooking up gauges. In most every home tested static pressure was a persistent issue. Rules of thumb on static pressure should be avoided. Refer to manufacturer specifications and work to obtain the required static. The industry engineers who design the equipment know what system output is required. If we short cut static pressure requirements with generic information or rules of thumb we will fail to gain comfort or energy savings. Deltas- Temperatures can identify issues early however don’t be fooled. A Delta T without air flow requirements validated can lead us down a meaningless path. This is similar to superheat and sub cooling. Without verified air flow present, superheat and sub cooling readings are bogus. Return air adequacy- Return air continues to challenge our industry. We continue to follow a trend of increased return air size to provide adequate flow for our systems. This includes a practice of increasing filter area. Seldom will systems of three ton (nominal size) or larger

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