Last year, 2024, we replaced four PTACs with a mini-split AC. I’ve been asked about it often enough (by neighbors, coworkers, friends) that I decided to write up the experience. Hopefully it’s useful for you, too.
Overall this cost us about $40k, including the cost for closing up the PTAC holes. We’ll probably never make the money back on electricity cost savings, so the main benefits are that we have more quiet and more stable temperatures now and overall I’m glad that we did it.
(I’ll use the term “heat pump” and “AC” interchangeably. Every “AC” mentioned in here can do both heating and cooling)
Prologue
We bought this apartment at the end of 2023. The old owner had installed four brand new PTACs at the beginning of 2023 to get ready for selling the apartment. I don’t know the actual reason for this, but I assume the old heaters were nearing their end of life or were broken already. In any case the new thing they installed were really bad. They’re by Islandaire and they’re loud and they are warm-weather heat pumps only. Meaning as soon as you get close to freezing, they switch to backup heat, which was just electric resistive heating. This makes no sense for two reasons: 1. It gets cold in NYC, and 2. we actually had gas pipes leading to these ACs so the backup heat should really be gas. In the winter we would run on backup electric heat for months.
The most expensive electricity bill that year was $1200. Which is a lot for a three bedroom apartment with neighbors above, below, to the left and to the right.
And to top it off the PTACs had been installed wrong so they would drip inside the apartment and warp the floors. We noticed this fairly quickly but at that point they had been running for months without anyone living in the apartment and the floors were already damaged. Also apparently the old owners had sanded the floors while keeping the ACs running, so the filters were completely clogged by sawdust, and even after we cleaned those, one of the ACs never fully recovered and broke completely within a year. In theory there was warranty on these, but we could only ever get the person who installed them to come out once. After that we were completely ghosted. We debated suing but we didn’t actually want to keep these ACs for a second winter, so why go through all the trouble to force a repair on a thing that we didn’t even want?
So we had to get a new AC before the winter.
Research
I live in a second-floor apartment that only has windows in the front and the back, with no roof access. I have access to a backyard but there is no way to get large machinery back there. So geothermal heat pumps were impractical, and the only real option is to go with a regular old mini-split with one large outdoor unit in the back and four terminals inside, with lines (pipes?) running through the walls.
... continue reading