Mini split installation location

Reaching out to the experts today to ask about location of installation of a mini split.  I'm a realtor, not an HVAC contractor.   I'm working on a "flip" that will be more energy efficient than most, think HPwES.  For the separate detached casita we are replacing a window AC unit placed in a sealed off window with a new 3 x 3 window and a mini-split.  An HVAC contractor is proposing the muni-split to be installed on the same south facing wall as the newly installed window.  

The picture belows shows the entire lot and arrow pointing toward the detached casita.  It looks attached, except that the white patio covering does not have walls.  It backs up to the outside laundry room which backs up to the carport and ensuing driveway. 

An HVAC contractor has proposed it best to install the new window and mini-split on the same south facing wall of the casita.  

My idea is to install  the mini-split on the west wall.  Your first thought is why the west wall.  The west wall is in the middle of the casita, across from the front door.  There is a bathroom inside this unit, to the right of the entry door.  The entry door ison the east/right side of the casita.   I also think of air flow and how one affects te other?  We have wonderful winters in Arizona where we can sleep with the windowss open.  We could expand the window size to 4 x 4 if the mini-split was on another wall. 

My question to you all is - which wall would you install a minisplit?  

On the same south wall where the window is located; 

On the west wall to be more centrall located; or 

On the east wall to the left of the entry door?  


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  • The house structure matters a lot for the installation of the heating system because if the insulation is poor then the system will not provide proper coolness or heat properly in all directions. The system needs the best installation by the professional contractors like All Week Heating for the system to give longer services. Because the duration of the system depends half on the installation and half on the use and maintenance of the system. 

  • Being a Flip you must consider the install cost. At least get a bid for a PTAC unit like the ones found in most hotel rooms.

    With either choice I would put it on the long wall so it is closer to the center of the room.

    If the unit is mostly for cooling mount it higher on the wall. If it is more of a heater get a floor mounted unit.

    Most mini split manuals require 12 inches of space above the mini 12 inches of unit unless the ceiling are very tall over the window is not going to look very good.


    • Thank you!  Most people think cheap when they hear the word "flip."  While cost is a factor, our mission is not cheap but efficient.  We're also installing all new ducts in the main house, new HVAC roof mount.  Removing an old evap cooler on the east side of the house and all of that ductwork; installing all new appliances; hopefully, sunscreens.  

      I think we are going with the west wall given that it will be on the long wall.  I may report back on a separate post the outcome as I've been going back and forth with an energy auditor and HVAC company on best practices for this location.  

      Thank you for your comments!

    • I agree that the south wall would be shaded for the warmer summer months, but it won't look right aesthetically having a window and a wall-mount mini-split on a 7' wall.  I think the wider west wall would be better. We can place it low enough, 12" below, and it would look fine.  

      Thank you all so much for your time and talent.  I appreciate your wisdom! 

  • South Wall. It will have the highest load needed for cooling/heating. the shade from the tree could help the outdoor unit operate more efficiently in the summer.

    Look into a mini split with a sensor for hot/cool spots. It will direct airflow to where is is needed solving comfort issues.

  • I would add where is the power coming from?

    how much room for the condenser on the west wall it looks tight over there and I would want 12 inches clear for the condenser 

    the south wall proposed might have easier access for the electrical run

    • I'll check on electrical.  Good point.  

  • First: Mini split are a great option.

    Second:vI agree with David that installing on the south wall, above the window woudl work.

    Mini Split Air Conditioning System Ductless Central Heat Pump AC
  • Hi Jan, in a room like that with a relatively balanced aspect ratio, flat ceiling and not much glass, the mini-split could probably be located on any wall. With the information provided, the west wall looks good, preferably near the center. 

    In general, if a room is much longer than wide (e.g., bonus room), the unit needs to go on an end wall since mini-split throw patterns tend to be longer than wide. That's doesn't appear to the be case here.  Also keep in mind that a wall unit (as opposed to a floor model) needs to be mounted high to avoid 'face washing' and interference from furniture. (Note: Different models can have very different throw patterns.)

    Here are some of the things I consider when deciding where to mount a wall unit: room shape, need/opportunity to condition an adjacent nook or room, interference (e.g., soffits or curtain walls), furniture layout and of course, aesthetics.

    As an aside... In hot climates, I always try to locate the outdoor unit so it doesn't receive afternoon sun. The benefit is relatively small (on the order of 5%) so it may depend on what that would do to refrigerant line length and routing. For example, you wouldn't want a long run along an exterior wall, especially if it's exposed to direct sunlight.

    • Hi Jan, actually, I said you'd be fine putting it on the west wall since you want a larger window. Keep in mind it's not necessary to set the outdoor unit on the same wall as the indoor unit. Also, according to your drawing, the room (excluding closet and bath) is only slightly longer than wide, not nearly enough to impact placement.

      I disagree with Daniel's recommendation to locate unit on south wall since it may have the highest load. There's no logic to that, since the air is directed AWAY from the unit.

      Walter noted that some manufacturers recommend 12" spacing between wall unit and ceiling. Since you have limited ceiling height, I would not assume 12" is required. Clearance requires vary by model. Check the installation instructions.

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