hi there, i am considering installing central air and heat in my home. i have done some research and it seems that an all in one package unit would suit my needs well, but i am having trouble finding info on air handlers. is this unit to assist in just moving the air through the home;is it the same thing as a package unit,or is it even necessaryto have one with these all in one units? any help would be greatly appreciated. thanks very much.

From my understanding of air handlers they would be used in areas where not enough air is coming out of the vents. If you have a very large area to heat and/or cool you would get a separate air handler. Most times you don't need such an item as modern a/c and heating units have enough power to blow the air in the ducts to all areas of your home.

You didn't give the configuration of your home, i.e. 2 story, large one story, etc.

The all in one units usually sit outside with just the ductwork inside the home. A split system has the furnace inside and the a/c unit outside with the a/c evaporator coils on top of the furnace unit inside the house.

normally not neccessary to need a seporate airhandler along with a package unit

if right size is bought the blower that is built in should do the job,,unless you have upstairs that is not fed buy the package unit

An all in one as you say, is usually used in commercial applications. The problem is they are more cumbersome to install in a home and you have to duct them, so longer duct runs and insulation on the ductwork would be required. Installing on a pitched roof requires a special curb. The nice thing is they are an all in one heating and cooling unit.

The air handler, would not have any means of heat, unless it is a heat pump, and resistive heaters can be installed within it, with a split AC unit installed outdoors. (A furnace can also be called an air handler, but would have some type of fossil fuel for heating) Depending on where you live, the air handler and split AC unit would be more popular.