Cool air in hot air out attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.
Central air in the attic.
If you have a horizontal furnace in an attic the evaporator coil will sit on one end of the furnace instead of on top.
If you place the furnace in the attic then you must install the infrastructure in the building to force the warm air to the bottom floor.
So why put an hvac system up in the attic at all.
With hundreds of square feet of ductwork surface area in the attic and a δt of 75 f the air coming out of the vents in your home will be significantly higher than 55 f.
That size can vary wildly based upon how well insulated the home is.
This is the piece of your air conditioning system that most people never see.
Central air in the attic not sure about the access size but the place to start which should have been done by your contractor before this unit was installed is to determine the correct size.
That means you have higher energy costs and less efficiency since you re blowing the air down instead of allowing it to rise naturally.
Most updated central air conditioned homes have a new air conditioner split system meaning the ac is broken up into parts.
The condenser in your air conditioner works hard to get rid of heat and pressurize refrigerant for the return trip through your house.
The total drop in efficiency can be up to 35.
If you don t have forced air the fan and coil system is typically placed in the attic where it will deliver cool air through ducts.
It s contained in a metal box called a plenum and sits on top of your furnace.
Typically this indoor unit gets placed in a cabinet or closet somewhere inside.
An attic can get up to about 130 f in the summer and the conditioned air entering the ducts is about 55 f or so.
Well mainly it s a way to save space.
Put it in an attic full of blown insulation and you re forcing.
Throw duct leakage into the mix and the problems are even worse.