HVAC upgrades: should we install Ductwork or a Mini-Split?

[Luke Babich]

New 4-family property.

At Arch Buyers, my business partner and I just bought a 4-family property in St. Louis County. 

The two upstairs units have brand new duct-work. There are furnaces in the attic to provide forced air heating, and we're planning to install central air to both units soon. 

The problem: no duct-work downstairs. 

The ground floor units, on the other hand, have no duct-work. They have radiator heating and window AC. 

Making things trickier, the building has a concrete floor. The only existing gaps through the concrete are (unsurprisingly) already occupied by plumbing or electrical lines. It's a lot of concrete to drill through to install ducts. 

Here's a view from the basement: 

Should we install duct-work or a mini-split? 

The first unit we're rehabbing is 1450 sq. ft. We potentially could install a mini-split AC unit outside, and enter through a window or aperture on the side of the building. 

Would you recommend trying to install the mini-split, or spending the cash to install ducts through the basement? 

Is there another approach altogether that you would try? 

What factors would you keep in mind when making the decision for one of your properties? 

[Nate Maier]

Hey @Luke Babich,

Congrats on the recent purchase.  Just my 2 cents but I would go with a  split A/C system.  They are pretty common out here in Hawaii as many of the older homes, and some of the newer, weren't built for A/C so retrofitting in a central A/C system isn't worth the hassle.  Overall I've only heard positive things about them.  They are also nice as they allow your tenants to have "zones" depending on how many indoor units you put in, which can help reduce energy bills.  Just pitch it to prospective tenants as a "Green" living space!  

Going through that floor would not be fun, so I'm guessing any bids you get done to have a central A/C system put in wil be on the higher end.

Good Luck!

Nate