Arkansas HVACR NewsMagazine September 2021

HVACR NewsMagazine September 2021

Tech News

Leaky homes (pier and beam or double hung windows) can need one CFM per square foot of delivery. Homes on a slab with code concurrent updates can use no more than .8 CFM per square foot and homes built after 2007 may require .6 CFM. Where all aspects of construction incorporate an encapsulated perimeter .5 CFM or less is required. These numbers should never replace the Manual J Load Calculation. These are simple, brief comparisons, that allow validation of a proper Load Calculation. Hopefully everyone is familiar with AHRI (Air Conditioning Heating and Refrigeration Institute) directory. Manufacturers develop and maintain the directory to provide a level performance playing field when selecting equipment. Distributors provide matched systems components to the contracting community using the information. The data goes far beyond the SEER and EER providing guidelines for avoiding mismatched equipment. Anyone can access the data to insure what they or someone else has install is performing. The directory continues to be a super helpful tool when a contractor is in doubt. https://ahrinet.org/certification So, what can go wrong with improper evaporator selection or fan settings? The number one issue is believing size doesn’t matter if the equipment can vary refrigerant flow to match air flow. The number two ( yes BS ) issue is believing everyone should have an inverter driven system installed if they can afford it. Size remains a vital component where HVAC is installed. Under full load conditions an oversized system will result in the same way single speed systems do.

Low dehumidification capacities. These modulating air flow machines are more susceptible to dewpoints met in unconditioned space that leads to condensation, sweaty deteriorating ducts. on the second point is fundamental. If you install an inverter system on a leaky home , you make conditions worse all the way around. Because the system is always running, you are introducing unconditioned air into the home continuously. Utility bills rise and comfort goes in the toilet. Generally variable capacity systems are great for well built, efficient, homes and can be super helpful in larger homes. Fan setting play an invaluable part in comfort and efficiency. During a study of over 15 homes, only three had fan controls adjusted correctly. Most fans setting had been left untouched at the installation. In some instances, the system was only 6 months old, and others had been functioning at default for over a dozen years. During cooling, air flowing too fast will not stay in contact with the evaporator long enough to exchange heat or the force of the air will blow water off the evaporator, possibly contaminating ducts and providing condition favorable for biological growth. Unnecessary air speeds tax filter function Air flowing too slowly will leave refrigerant behind failing to capture capacity. During heating there are too many conditions to discuss in this article. Air moving too fast will not stay in contact with the heat exchanger harvesting heat similarly to the cooling cycle. Combustion can be extremely inefficient or ineffective, damaging components and putting occupants in danger with out-of- The BS