DIY Central Air. Got a question for you guys. Install in attic or basement?

[lugoismad]

I'm going to install my own central air unit in my house. A friend of mine has a buddy that redoes houses, and he has alot of spare parts around. I can get everything I need to install it besides the refrigerant and duct work for less than $500 for a 3-ton unit.

I can install it in either my attic or basement.

With the attic option, my blower is not struggling to push cool air to my 2nd story, which seems like a definite advantage. I lived in a 3 story house and my bedroom was in the 3rd story, and it was always hot up there because the blower couldn't push the air up there.

With the basement option, I can put the air handler closer to the compressor, and the basement stays cooler than the attic.

Which would you do?

 

[Highbeam]

You're simply talking about the air handler location? I would put it in the basement. I don't want the water damage potential from the condensate. Don't want the noise at night, don't want a long distance between the compressor unit the air handler, and don't want the hassle of filter changes up in the attic. If the blower can't move air to your top floor then you either need better ducting or a better blower.

Do you have ducting already? Would love to hear more about the retofit of ducting if not.

 

[lugoismad]

You're simply talking about the air handler location? I would put it in the basement. I don't want the water damage potential from the condensate. Don't want the noise at night, don't want a long distance between the compressor unit the air handler, and don't want the hassle of filter changes up in the attic. If the blower can't move air to your top floor then you either need better ducting or a better blower.

Do you have ducting already? Would love to hear more about the retofit of ducting if not.

No, I do not have preexisting duct work.

I am installing 3 duct runs for my wood burning furnace, but they will not be attached to the AC.

The reason I'd like to install the AC in the attic is because It could be located in a central part of the house which would make the duct runs to every room less than 10 feet.

Also, putting it in the basement means I'd need to hollow out a wall joist in order to pump air to the 2nd floor, which will be a mess.

 

[Hogwildz]

Personally, I am going to be going with a mini split ductless.
More efficient & no ductwork.
Sounds like you might be getting older stuff, less efficient & mix & match.
Remember, you get what you pay for.
And must be properly sized. Too small, won't cool enough, too large, will continue to cycle & waste energy.

 

[Redox]

Definitely go for the attic; that's where all the heat is! Even with duct losses, it will be more efficient. AC works much better with high returns and high supplies. Why fight to get the ductwork all the way up to the top of the house, when you can punch a hole in the ceiling and you are already there? If you go down south, this is how the majority of new houses are done.

Code now requires a secondary drain pan under the air handler in case the drain clogs up. Run a second drain line out the side of the house so you will see it if it drips. Hang the air handler from the joists with threaded rod and angle iron with rubber isolators. If your ductwork is sized correctly, it will be hard to tell it's running. Most manufacturers do not derate their units up to 50 feet of lines and if you have to go over 50 feet, upsize the lineset and maybe lose a couple percent in capacity. A filter grille in the ceiling is a wonderful thing if your attic is hard to get to. Make sure everything is well insulated and all will be fine.

Ductwork is a PITA, but it may be possible to find a sheet metal tech who will help you. It really helps to have a shop to make up all the duct pieces as the ready made stuff rarely works out that well. If you want to go budget you can put in a Sears octopus; ie, a metal box on the inlet and outlet that you can connect the flex duct to and run to the wall/ceiling diffuser. Flex duct has more resistance to airflow, but is much easier than metal duct and is preinsulated.

Less than $500 for an air handler and condensing unit implies that the equipment is used. Used equipment may be fine, but there is almost no way to tell until you install it and try it out. I personally won't get involved with a used equipment install as the few I've done have left a less than satisfactory customer and sometimes a lot of finger pointing. It is possible to contaminate a refrigerant system with dirt or moisture and that will cause a lot of problems in the future. There is a lot more to a refrigeration system than sweating a few lines together and filling them with refrigerant. Those lines ought to be inert brazed with 15% silver and evacuated below 400 microns.

If you are going to go to all the trouble, it might be worth it to get new equipment with a warranty. Then you can get the latest technology and efficiency along with a warranty. I'd also consider looking at a heat pump as they are only a couple hundred more dollars than an AC system and can save you money in the spring and fall shoulder seasons. Save your oil and gas for the really cold weather!

Chris