Duct Sizer: Size, Condensation

A field calculator for duct size and insulation thickness. Enter the airflow and it gives the size you need; enter the size and it gives the airflow that size can carry. Enter the ambient air and the air inside the duct, and it tells you whether the duct will sweat and how many inches of insulation stop it. ■ There are two limits, not one The friction rate and the velocity. This app shows both, and says which one governs right now. Look at only one of them and you either get noise you did not want, or a duct that is larger than it needs to be. ■ How much insulation stops condensation From the ambient temperature and humidity and the temperature of the air in the duct, it works out the outer surface temperature and the dew point, then rounds up to a stocked thickness (1/2, 1, 1-1/2, 2, 2-1/2, 3, 4 in.). When no thickness can stop it, it says so, and separates the two reasons: - the dew…