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Community and Q&A

Locating multiple ductless outdoor units

srivenkat | Posted in Mechanicals on

I am planning to have 3 Fujitsu 9RLS3H units installed on the side of the house. The area is L shaped, the base of the L being a garage wall. There are typically winds blowing into the base of the L from over a pond from the WNW direction.

I was originally thinking of installing the units perpendicular to the base of the L, because I remember reading somewhere that the front of the unit should be perpendicular to the wind direction. But then I also read elsewhere that the outdoor units should NOT be located such that the outflow of air from the front of one unit is directed at the inflow on the back of the second unit, etc. I am wondering if this can be done with some sort of added clearance. The base of the L is at an elevated level whereas the side slopes, hence my preference for the base of the L. I plan to have a platform about 2 feet off-the ground to keep away from snow in East Central Illinois.

Thanks in advance for any advice.

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  1. GBA Editor
    Martin Holladay | | #1

    I would install the units parallel to the nearest wall, not perpendicular to the nearest wall, so that the fans aren't blowing at each other.

  2. srivenkat | | #2

    Thanks for the suggestion, Martin. In trying to choose which wall they should parallel, does wind direction matter? Is it OK for wind to be blowing into the front (air outlet) of the units? Or should they be installed such that the wind blows into the back inlet of the units? Or should the wind be blowing only into the side of the unit? Thanks in advance.

  3. Expert Member
    Dana Dorsett | | #3

    The effects of prevailing wind direction will be quite small most of the time, but if you want a wind-assist, blowing from the back would move air through the coils with or without the fan motor being active. But when mounted parallel to a wall, the wall would be blocking the wind.

    Mounting it so that the fan blows toward the wall would require a larger distance between the compressor unit and the wall. The minimum specified distance for the AOU9RLS3 to obstructions in front of the fan is 8", but doubling or tripling that would be necessary to get any help at all from the wind. See page 02 - 02 (p.39 in PDF pagination):

  4. srivenkat | | #4

    Thanks, Dana. I am also curious about the wind baffles recommended for low-ambient cooling. I wonder if they entail any negatives in the heating application.

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