Return Air Duct Design

Just to note that we will use a cp of 1 026 kj kg k as standard and the delta t should be less than 10 c so we ll use 8 c.

Return air duct design.

Duct fittings and terminal units. Duct sizing duct calculation duct design energy efficient ductwork design. If you need a longer duct add either another sec tion of the unico return duct or a length of plastic core flex duct between the unit and the unico return duct. 9 1 distributed return.

Return duct systems. 8 7 rules of duct design acca manual d residential duct systems 9 0. 9 2 central return. The unico return duct upc 04 xxxx is an acoustical flex duct 10 ft 3 m long.

This is the best configuration and mandatory if the unit has a 5 ton blower. They should be on interior walls across the room from the supply ducts that should be washing exterior walls with conditioned air the red arrow points to a large wall mounted return air vent. The problem with bedrooms occurs in houses where the hvac design did not include return vents in each bedroom. To maintain balanced air pressure and air movement your duct system needs return vents for air in the room to be pulled back into the hvac system.

9 3 pressure balancing. 10 1 duct fittings and transitions. The third example shows a return air base beneath the air handler furnace. A person can be forgiven for not knowing much about their home s air duct system.

The furnace or air handler is probably on the other side of the wall. The furnace or air handler ahu in the drawing below pulls air through the return ducts conditions that air and then sends it through the supply ducts back into the house. 10 3 fire and smoke dampers. 10 2 volume control dampers.

An hvac return air duct should be in every room except a bathroom and kitchen. Each one in a system can add as much as 80 to the tel. This duct does an excellent job of absorbing sound from the blower. Rounded throats on ells drastically improve airflow especially a rounded inside throat.

10 4 diffusers grilles registers. Square ells return or supply are a bad idea. And δt being the temperature difference between the designed air temperature and the design return temperature. The return air ducts in an hvac system are especially liable to get taken for granted even though their part in heating and cooling your home is just as essential as supply ducts.