Arkansas HVACR NewsMagazine May 2024

HVACR NewsMagazine May 2024

Tech News

So why do zoned systems still struggle and waste energy even today?

sensor is satisfied and the zone is shut down. Like any process, it takes time to accommodate change. As contractors, you can move the industry in the right direction by getting air flow right. Parts may have to be ordered since the industry is behind the curve, and all your personnel brought up to speed. The important thing is to control your own destiny as best you can. You can follow the crowd and remain in the pack delivering inefficient performance, or you can take the lead and move ahead of everyone else. The choice is always yours. Too bad many in our industry are satisfied with the status quo.

We forget the terminal device. We forget grille performance and airflow delivery. We have the technology, but we administer air the lazy way. You can blame it on the manufactures, you can blame it on zoning suppliers, or you can step up and take responsibility for you and your company. Neither the manufacturer nor the supplier see the challenges you face administering the duct system in any specific home. Grilles have a requirement for air to be delivered at velocities from 300 to above 900 fpm depending upon the application*. If we modulate the air flow, we disregard all the information the grille is designed to provide. Take away face velocity and you lose drop, throw, and spread of the terminal device. It remains a best practice to maintain the required face velocity, so the grille lives up to engineering expectations. Most equipment manufacturers allow control of static pressure. If we use zone temperature sensors tied to non modulating dampers, the face velocity of the grille will be maintained and our target for air flow will be achieved. The compressor capacity will modulate due to static pressure requirements, and the grilles will deliver capacity until the

*Hart and Cooley 301 grilles