Residential Hvac Duct Design Example

The following duct sizes are based on a fraction drop of 10 inches per 100 feet of lineal duct.

Residential hvac duct design example.

Ordinary heating ventilating and air conditioning duct systems read air pressures at 0 4 psi or less often much less. Includes a full worked example as well as usin. This hvac for beginners section begins here with a discussion about forced air duct systems the basics the how and why of duct sizing. 10 psig 14 7 psi 24 7 psia.

That is really shocking. Designing a duct system is important but there are a few critical steps that come first. And i ve seen a lot of times how hvac contractors changed duct designs made by engineers. A unfortunately majority of residential hvac contractors have no idea of the heat gain loss calculations and duct design.

You ve got to know how much heating and cooling you need for each room in btu hr. Ductwork is simply an air delivery system. But what i experienced as a new residential hvac service technician. Hvac for beginners the residential forced air duct system.

They don t do it and don t care. This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Larger volumes or higher static pressures should be dealt with on an individual job basis. 1 psi equals 27 7 inches of water gauge.

For example if the gauge reads 10 psig then using the above equation the absolute pressure would be 24. Typical trunk and branch duct systems.