• I live in New York City, and it gets very hot/humid here.
  • I like natural light, i.e. I hate blocking my windows with a huge/ugly air conditioner.
  • I care about electrical efficiency, i.e. I hate paying to energize multiple huge/ugly air conditioners.
  • I rent my apartment, so I can’t modify the structure by drilling into the outside brickwork. I can drill into studs so long as I patch it when I move out.
  • I avidly seek to eliminate minor inconveniences no matter the cost or complexity, i.e. I’m OCD.


Mini split Air conditioners:

  • Are about twice as power-efficient as their window-mounted counterparts on average.
  • Are much quieter; ~1/10 the audible noise.
  • Can also provide heat in the same blower.
  • Are available in 120v up to around 14K BTU in cooling power, and 240v versions go well past 14K BTU.
  • There exist products that can sum two separate 120v lines to create a single 240v line, so long as each line is on a different phase.


Mini split air conditioners:

  • Require a dedicated, GFCI-protected power circuit. Usually around 20A.
  • Like any exterior power feed, require an external disconnect box.
  • There is only single-phase 120v power coming into my apartment.
  • Require professional line preparation (evacuation, filling with refrigerant, tube bending and other things).
  • Require the interior blower and external condensor connection to be within a specified length, e.g. 45ft.
  • Require semi-permanent mounting of the interior blower.
  • Require rugged permanent mounting of the exterior condensor.
  • A mini-split A/C unit is 3x to 5x as expensive as a window unit of similar cooling capacity.
  • 120v systems stop at 12K BTU cooling capacity.

A Non-Destructive Solution

After looking at everything, it seems like we can make a simple bracket for the A/C condensor, feed the refrigerant and power lines through a simple block set in the window frame, then run the lines along the ceiling to the blower. Might have to saw a medium hole (2 inches?) through one wall to pass the lines through.

Major design choices:

  • S-shape bracket made of aluminum box-tubing, so it’s not crazy heavy as we wrangle the bracket with mounted condensor through the window frame.
  • Bracket rests nearly all weight and vibration on the exterior brick wall and window sill.
  • Bracket projects through the window frame and is held by a bar that presses against the load-bearing structure of the window frame itself.
  • Adjustable feet on exterior bracket and retention bar.

Fusion 360 Project URL:

Making it happen

I measured a bunch of things:

  • Window frame.
  • Window sills, interior and exterior.
  • Dimensions and weight of the A/C condensor.
  • Locations of mounting holes, refrigerant and power lines on the A/C condensor.
  • Required refrigerant line length to reach the blower where I’d like to mount it.
  • Confirmed the 120v outlet to feed the A/C condensor is a 20A circuit, with no other significant loads plugged into it.
  • Size of my bank account.

To Be Continued…



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