How air handler units work?

[eng78]

Ok I'm a rookie to all of this and I just wanted a better understanding as to how an air handler unit operates. Basically what's the purpose of return air and mixed air? I'm sure you guys can help me out with this. Also if someone has any links to a sight where I could read further through into the operation of an air handler unit. Thanks.

[ralphtheplumber]

It's called an economizer.

A portion of the air returned from the building is exhausted outside, and replaced with fresh air. Then, the mixture of return and outdoor air is conditioned and blown back inside.

Did that help?

[snipe70e]

Originally posted by eng78
Ok I'm a rookie to all of this and I just wanted a better understanding as to how an air handler unit operates. Basically what's the purpose of return air and mixed air? I'm sure you guys can help me out with this. Also if someone has any links to a sight where I could read further through into the operation of an air handler unit. Thanks.

the purpost of return air is to save money.

Examples
it is 40 degrees outside on a once through system that air has to be heated and delievered to the space. The return air will have the range of 68 to 76 degrees and can be added to fresh air to temper the supply air.

On a 100 degree day on a once through system the air has to be cooled and delievered to the space. The return air can be added to the fresh air to again temper the temp of the mixed air.