Attic installations are common. That said, they are out of sight, out of mind, and bad things can happen before the home owner is aware of them. Number one problem is a clogged condensate drain. The next thing you know, you have humidity and rot problems in your attic.

Another problem is condensate pumps that are sometimes required in attics. That is another thing that can fail.

There is no way I would have an attic system. Most of them are up there so that they don't take up space in the residence. The builders don't care, and a lot of home designers don't make any provision for the mechanical space, so it ends up in the attic. I much prefer to give up a little space so that I have the indoor unit where I can give it a glance, every now and then. I do not want to crawl up into an attic to do that.

Also, consider that HVAC professionals will have to work up there. Do you think you could do your best work in a sweltering attic in the summer?

Today's new systems aren't that noisy, especially if they are installed correctly. Talk to an HVAC pro about it. In the meantime, provide for a mechanical closet somewhere where you can get to it, and provide a drain for the condensate while you are at it.

As an alternative, if you are in a moderate or mild climate, you can plan for a package unit that sits on a pad against the house. You have to make provisions to run the ducts into the home, but you don't have to have anything else inside the house. Just don't put it outside the bedroom window.

Package units can also be installed on roof tops.

In every house we have had we have had a unit in the basement and one in the attic.
As far as the condensation, we have a shut off switch so that if the line is clogged and the pan fills with water, the unit switches off.
In my opinion, With so much heat in the attic, I think the unit does not last as long as in the basement. That has been our experience.

High limit float switches can and do fail. I used to replace them all the time in a certain military application. It wasn't HVAC, but the principle was the same, and they were expensive switches to boot.

When most things of an electrical nature fail, something stops, and it is usually immediately obvious that something is wrong. When a high limit switch fails, liquid goes where it is not supposed to. Often, it isn't obvious until there is damage. That's the problem with them.

If an air-handler is in the attic it should be included within the conditioned space of the house. In other words, the attic rafters should be insulated instead of the attic floor.

It is usually pointless to talk in generalities about HVAC installations. Everything depends on how the ducts can be run efficiently and no two houses are the same.

I think there is regional variation in the popular location of the system. I had never heard of attic installations until I visited friends in the South (Georgia - lots more southern than Virginia, lol).

Why not plan for efficiency and convenience AND insulate well for a sound barrier? I wouldn't be influenced by what my friend's cousin's brother-in-law did unless it made really, really good sense. Personally, I don't see the benefits [other than a minor savings in space utilization which is cancelled by inconvenience in installing and maintenance] in having the system in the attic. And that opinion could well be my regional outlook.

Thanks for the responses. The "home" is actually a large garage with an apartment above within the 12/12 pitched roof. Only one 8x8 bathroom downstairs will be air conditioned.

It will be built on the Mississippi Gulf coast.

i have 2 HVAC systems and BOTH of them are in the attic.

leaks are not an issue. your main drain for teh air handler goes hard pipe either to a DWV pipe or outside. then UNDER the airhandler is a secondary pan with a seperate drain line. this one MUST drain to a place that you can see it easily. the secondary drain should never have water in it unless the main is clogged. so if you see water coming from the secondary, you know you have a problem.

the only time i have seen a secondary pan leak was at work. the 50 year old pan had finally rusted out and when the main drain clogged it dripped some on the ceiling.

here in MS, i am up in teh delta, attics are the main place the units are placed. you almost never see one in a garage or closet in a single family residence.

meldy_nva- I'm in Central VA and have walked through 100's of homes both before and during my build. Not only is the attic installation of the air handler common in Central VA...it is the norm. It's odd that this installation would never be seen 100 miles up I-95.

I am in SC and it is the norm here, too.
In 20 years experience with shut- off switches and attic HVAC installation, The shut off switch has never failed us.
It has saved us from a major leak at least 3 times.

van

I have had two houses - one with attic HVAC (NG & AC condensor) & my new home with the geothermal heat pump in condition space on the second floor in a closet. I do a lot of work myself - here is what I have learned over the years:

1. having the HVAC unit in the attic is common and works , but is not ideal. It stinks having to climb up into the attic to change filters or worse, having to work on the unit in the summer when the attic gets super hot or the winter when it is freezing out.

2. In the beginning we had a gas leak in the attic unit. Luckily I am one of those types who has to check everything a million times and I smelled the leak. We got it fixed and it never leaked again - but it sure would have been easier to detect if it had been in living space. That could have been a disaster.

3 I have sinus issues and needed to have a humidifer on the HVAC attic unit. I put one in (which my HVAC guys said was a no no) - but I did it anyway and it was a pain in the rump. I had to make a special conduit with a heat tape element to keep the humidifer supply line from freezing. It worked, but again not fun to service.

4. A heat pump in a closet is much easier to work on BUT it makes more noise. I had to add vibration isolation springs on the bottom of the unit to dampen the vibrations that came right through the second floor down into the main living space below. We also had to give up closet space in one of the bedrooms to fit the unit in (5' wide x 3.5' deep). Doesn't sound like much - but it is a lot of closet space to give up.

I think putting the unit in a conditioned space is ideal if you have the room. If you go that route - make sure they properly isolate the unit (lift it off the floor and suspend it from above - using vibration isolation springs dampers to reduce the noise.)

best of luck.

Hi, dixiedoodle ~ I don't want to commit to a "norm" because the population of my immediate area has doubled in the past 15 years, with an accompanying number of new builders. However, among cousins and friends who are GC or OB, as well as all the other builds I check out, there are no attic installations of HVAC or water heaters, with the exception of one alternative-lifestyle builder who is using the attic for part of the solar hotwater system. So while there could easily be some HVAC attic installations, I would certainly hesitate to refer to them as common... as I said, I had never heard of such until visiting in Georgia. OTOH, other than a bro in Richmond, and cousins in Newport News, I have no personal experience with builds in the southern or central part of Virginia. Although, when you consider it, the awkwardness of maintenance and replacement of attic systems seem to me to be good reasons for *not* putting such equipment in the attic.

I have never used a gas appliance in an attic. In the northeast it is common to install upper and lower airhandlers served by a basement boiler and outdoor compressor/condenser units. The intent is to reduce duct runs.

around here the filters are installed in teh returns, NOT in the airhandler. the homeowner never even HAS to go up in the attic to do anything with the AC.

We have the same situation as davidandkasie.
We only have to replace the filters in the returns.

Here is an interesting post. It shows and discusses one particular attic installation.

Here is a link that might be useful: Attic HVAC Installation

Here's a good study on A/C performance.

http://www.fsec.ucf.edu/en/publications/html/FSEC-GP-66/index.htm

Where I am it is typical in larger 2 story homes (homes requiring 2 air handlers) to have one air handler in the basement (handling the first floor) with the boiler and water heater/super stor. The second air handler is in the attic. Ours is hung from the rafters, further reducing the noise. I hear it come on (barely and if the TV is off), but I have Spidey hearing (DH can't hear it). There is a pan under the air handler and it drains to a drain in the basement. If the drain fails there is a float switch and the air handler shuts off.

Ours is not in the conditioned space, as it should be. The HVAC people around here resist that. When we finish the attic we will probably do it then. We have a filter at each air handler. The one in the attic is a regular one you change and the one in the basement zaps the dust and has to be washed. I always thought the filters on the returns messed up the air flow? Maybe that's a myth, I don't know.

Mighty Anvil asked....What kind of HVAC system? Is there perimeter eave space around the second floor perimeter?

I don't know as of yet what system will be used. Probably something rather standard. And there won't be much eave space as I see it.

(please see link... Our plan is a stretched version of this plan, with the bathroom moved to where the bedroom is now and the plan stretched another 12 feet to make room for the bedroom that the bathroom pushed aside.)

As we have drawn the plan now, the living room goes from gable end to gable end, and we'd like to vault that one room's space. In other words, there will be two zones of attic space....one above the kitchen... and one above the new bathroom and bedroom. The vaulted living room will cut these two attic spaces from each other.

Only one 8x8 bathroom AC'd on the bottom (garage) floor. However, we are considering a temporary (5years) guest bedroom downstairs. Considering a window unit for the temp room.

No basement and sited on the MS gulf coast. Hot and humid.

Thanks for ALL the responses... Gary and Frog... I will look at the links tomorrow.

....Spidey hearing ....!!!

Here is a link that might be useful: garage apartment

Just to clarify - in my attic install I had no air filters in the attic, these could be changed from the living space. However, the humidifier filter was in the attic and it was a pain to change. Service was difficult too during extreme temps - summer afternoon's were the worst.

I suspect A/Cs will usually go out of order on the hottest, humidest, most miserable summer afternoon. That's when they are stressed utmost.

sniffdog ~ do you mean that each vent in each room has a filter? or that there was some access from the living space to a centralized duct? I'm not uptodate on ACs, but I've not noticed any that didn't have a filter protecting the initial duct (who wants pollen bouncing around their duct? catch it before it gets inside).

suspect A/Cs will usually go out of order on the hottest, humidest, most miserable summer afternoon. That's when they are stressed utmost.

Not quite. That's when humans are stressed the most, and it just seems like all the A/Cs pack up then.

the pics i see are the biggest butcher job HVAC i have seen

If you think the pictures in frog_hopper's link are the "biggest butcher job HVAC" you've ever seen, maybe I should post some pics of the job my Builder and his crummy HVAC subcontractor did on of mine! It makes those pics look like an "A #1 quality" install.

Builder has been fired and we're doing what we can to clean up the HVAC mess before finishing the house but....