Type of Air Conditioning
What to do to stay cool
To be honest I started looking around the internet for Central Air units because of the massive heat wave/ heat index rise that has been floating over the Northeast. While I work for a heating and cooling company, I just bought a house that I don't want and can't do major work to, yet. That didn't mean I haven't asked around to figure what is involved.
My home doesn't have ductwork as it is a forced hot water boiler heated home. I have baseboards in all the rooms that bring heat to the rooms, meaning that I can't just add central air conditioning to the ductwork in my home. That doesn't mean that I can't add ductwork to the attic of my home to get central ac.
There are several different types of AC that you can have installed in your home, which we've talked about here before. Central AC, Mini-Split ductless AC, Window AC, and Portable (not even worth the hassle) each have their own benefits and downfalls. Right now we'll just talk about the benefits and hurdles of installing Central AC in a home that doesn't have ductwork.
When thinking about Central AC we have to look at all the rooms you want to cool, the energy efficiency you desire, and the placement of the ducts and vents. If you have a multi story home you also need to consider whether you're going to cool just the floor below the attic or any other floors, which can add to your cost. The main reason you might want to consider a central air system out of your attic over several mini-split systems is the cost associated. Ductwork isn't cheap but neither are mini-split systems, at several thousands of dollars each cooling several rooms with multiple units can run you almost 10k. Where a duct central air system isn't going to be much cheaper, you won't have to pick and choose which rooms are cooled and which aren't. If you want to have central air instead of windowed units, the main upside is consistent temperature throughout the cooling area, like with mini-splits you won't have to pick and choose the rooms you cool. The drawback is of course a gross price difference, you could get away with cooling a four bedroom upstairs for less than a grand with window units.
If you're still interested and trust me down the road I'd like to take this road, what is actually involved in putting central air in the attic and where can it go. First we'll cover what is your central ac unit. It will consist of an outside unit the compressor, the inside unit the air handling unit, ductwork, piping, and registers. Next we'll cover how you ductwork will work to deliver the cool air. In most cases you'll have square or rectangle shaped duct system installed in your attic with registers that will bring cool air into your rooms. Pretty simple, now this would just be on the second floor. If you want to have central air on the first floor, this can be a little tricky, expensive, and intrusive. Best case scenario is that ductwork can be installed without much disruption in a closet or other unseen areas. It all really comes down to how your home was built and where can the installer get. At the end of the day you may to settle for ac on the second floor and not the first.
Another thing that you'll need to consider is the tonnage of your ac, the word ton may shock you but remember you are cooling a large area. Most central air units come in 1/2 ton increments, you'll usually find tonnage ranging from 1/2-4. The amount you go with is similar to finding the right ac unit for a room, too much and you'll overpay up front, too little and you're system will have to over work to keep you cool.
Now one concern or issue you may find online is that an attic is hot and not the best place for a central ac unit. While it is true that having ductwork based in your attic isn't as good of a place as built into the walls during a new construction, that doesn't mean it can't be done and done properly. In most cases it is about 140 degrees or so in your attic if you have a black shingle roof. That means that your ductwork in the attic will be around that temperature, but you want to pump 68-72 degree air through there to cool off your second floor. The best way to get around this is to have your ducts properly insulated and sealed. You should also have a delay switch installed, this makes is your air handler will start blowing out the hot air through the duct and out of the house before pumping in and wasting air conditioned air. One more thing you might wonder is, where does the hot go from the unit in my attic. As we know anything that makes something colder has to remove hot air, be assured that the hot air isn't going to go into your attic. Most of your hot air will either absorbed by the refrigerant or will travel outside.
Is central ac in a home without any ductwork the most ideal situation, no. Can it be done properly while keeping you cool for summers to come, yes but it'll depend on the company you have do it.