Measuring air flow in an HVAC duct can be a tricky business. Paddle wheel and turbine flow meters introduce not only resistance but maintenance issue due to accumulated dust and debris.

He found an interesting white paper that described measuring airflow with a single-path acoustic transit time flow meter ... up in a PVC pipe and blew air into it with a fan.

Despite what you might have heard, HVAC experts say that closing vents in unused rooms is not an effective cost-saving measure ... air conditioner (central air) utilize the same vents. Proper air ...