Quote:
Originally Posted by vreihen16
I think that you're confusing a "package" system (air handler outside) with what we did.
Our house's small size means that the smallest conventional unit (2.0 tons) is overkill. At the time, we got 20 SEER (in a 1.5 ton system ducted "ductless") for less than a 14 SEER in a traditional 2.0 ton. The type of air handler that we used is on the right in the first picture above.
The previous owners sealed up all attic access in our single-story house, and I have no inclination to open it up and find out why to route stuff down through the ceiling. We also do not have free wall space for a traditional (cheap option) ductless air handler. Our only option was to come up through the floor from the basement, with ducts of some sort.
We hung the ducted air handler in the center of our basement (more like a crawl space, and ran sheet metal ducts to all four main rooms...poking up through the floor. I fabbed up a custom sheet metal return plenum to the basement through a kitchen cabinet, as well as a custom sheet metal distribution/splitter plenum for the outlet side of the air handler. All in, we did the whole duct install for ~$150 in materials at the big box store. Some surplus air handler insulation and scrap insulated flex duct showed up at our door from a friend, which we used to insulate the ducts and air handler.
The one pitfall of the ducted "ductless" system is that it was designed for use like in the second picture above with no restrictions and short duct runs. The fan can't build the full pressure of a traditional air handler, so everything had to be engineered with minimal duct bends and restrictions. Flex duct has more restrictions than sheet metal ducts, and believe it or not sheet metal is cheaper because HVAC contractors are apparently lazy and go for the flex duct. The sheet metal not only saved us money, but it also gave us the ability to have the ducts cleaned in the future without having the worries of tearing a flex duct liner out.
I had to learn duct sizing and engineering, the sheet metal trade, and even went to get the EPA certification so that I could legally handle the refrigerant. Considering that I had never even lived in a house with central AC or forced air heat before, this was a *huge* learning experience. My in-laws thought that I finally lost my marbles when I started this project, but now they come into our house for visits and comment how cool it is on the warmest summer days. (I jokingly said to my FIL when the AC was finished that my next DIY project was going to be 20 solar panels on our detached garage roof...which would be way easier than the heat pump project.)
For our SC barndominium project, using 2-3 single-zone mini split compressors is my first choice. Since we are going with an open concept (warehouse/industrial) house concept, I also have the option of using a traditional HVAC system with exposed ducts hanging from the ceiling. Of course, we would lose the failure redundancy with a traditional unit.....
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Got it. So your install in an existing structure dictated some of your choices. if you were doing a "clean sheet", new build, like I am, would you do it all over the same again?