Metal and flexible ductwork need to be sealed to guarantee that it is reasonably air tight for maximum efficiency use an approved foil tape or duct sealant.
Cold air return in attic.
Do not return air from bathrooms and kitchens.
If that return duct is pulling in any outside air then the opposite has to be happening somewhere else in the system ie it is pushing out an equal amount of heated air.
A fan draws air from the house into the system through return air vents image 1.
An attic over a garage that doesn t have room for an actual entrance is usually treated like an unheated attic and totally sealed off from the house.
This pulls the air across your body.
The return vent pulls cold air from the bottom of the room and returns it to the furnace to be reheated and returned as warm air.
To explain the components of a forced air system.
Most of the openings which allow air to escape into the attic can easily be overlooked.
Any water vapor in the warm air rises until it reaches the cold roof deck area at which point it cools and condenses back to a liquid phase.
A return air temp b outside air temp c airflow across evaporator coil d return air leaks from attic if you measure supply and return temperatures at the grille and at the air handler you can get an good idea of where your biggest losses are occurring.
If the supply ducts are in the floor then the return air should be located up high.
They can be placed into staircase cavities stacked closets that run one on top of the other or in stud cavities in the wall.
During cold weather gas burners create heat in the heat exchanger image 2 which in turn heats the air.
Cold air returns are sized 1 5 times above the supply capacity to prevent negative pressure in the system.
The flexible design allows for connection of a new or existing side air return on either side based on the placement of the reinforced sheet metal panel of the return air box assembly.
These vents are seen in many types of furnace systems although there are alternatives such as drawing air from the outside or from the area around the furnace.
Unlike supply vents return vents do not need to be cased in metal.
Condensation forms when warm humid air comes into contact with a colder surface like your air conditioner s ductwork.
At 21c i d guess you have a lot of leaks on the return side.
A cold air return is a vent that sucks cold air into a furnace so that it can be heated and brought back to a room through a furnace register.
The return air vent openings need to be on the opposite side of the room so the conditioned air is pulled across the room.
