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Community and Q&A

Minisplit outdoor location ideas

raul4817 | Posted in General Questions on

I am going to be installing a fujitsu 18RLFCD this spring. I have my duct design complete and I am still second guessing myself on the outdoor unit location. I have come up with 3 options,

option 1 is hanging it off the rear of the deck and building a snow cover this would be a 50ft lineset run to the 2nd story.

option 2 is hanging it off the brick under the deck, I have 41″ from grade to the bottom of deck joists giving me 8.5″ under the unit and above( 4″ required per fujitsu’s install manual) and no snow cover needed since this will see no snowfall but an occasional snow drift that I can clean as needed, the lineset would be 37′.

option 3  is to hang from the deck on the side and build snow cover, however this side will have a fence at some point that will be 36″ away from the front of the unit. the lineset here will be around 43′.

Im really leaning towards option 2 with the shortest lineset and no need to build an extra structure for snow protection.

I am in climate zone 5 so this unit will pull double duty, heating&cooling.
once my first floor and basement is properly insulated with new windows and if i’m happy with the fujitsu’s performance upstairs  I plan on installing a second unit for those spaces. Linset here will be irrelevant since it will travel no more than 25′ no matter where i put it in the basement.

I’m not concerned with the noise or added hot air coming off the unit in the summer if it were parked under the deck.  Im looking for the most practical and efficient install location.


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  1. joshdurston | | #1

    I think option 1, option 2 looks like you might risk recirculating cold air under the deck (reducing efficiency).

    Be careful with attaching directly to your house. Mine seems quiet and vibration free in the room beside the unit (or outside standing beside the unit), but the bedroom across the hall seems to have some weird low frequency throbbing harmonics depending on the compressor speed. If I could do it again I'd ground mount it on a raised stand system to decouple vibration.

    In a cold climate it's a nice bonus if the sun can hit the unit. This should help take care of any residual ice build that might occur occasionally. But airflow considerations, and line set length would definitely take precedence.

    1. raul4817 | | #3


      Yes there is a risk of water in the form of melting snow dripping on the unit under the deck. I am pretty diligent about cleaning snow off the deck. Option 1 gets pretty regular sun most of the day since it is south facing. My biggest concern with that location was the extended lineset.

  2. _jt | | #2

    If there is any way for water to drip through the deck you will end up with an igloo around your condenser. Why not hang it off the 2nd story wall? It will make your linesets much easier to manage and keep it off the ground. Ideally you want 6-12 inches between the ground and the condenser so there is room for the drain pan to drain.

    1. raul4817 | | #4

      I have considered hanging from the wall off the second story but decided against it mostly because of servicing convenience.

      This unit doesnt have an integrated pan heater and I imagine I will need to monitor that occasionally, not ideal when its hung 20ft up. Also the snow roof would be a bit more work and consideration. I originally planned for option. 1 and I have a nice closet space to fish the lineset through to the 2nd floor. My only concern was degradation of efficiency with a 50ft lineset although on about 13' would be outside with the majority inside my thermal envelope.

      1. bfw577 | | #10

        "This unit doesnt have an integrated pan heater and I imagine I will need to monitor that occasionally, not ideal when its hung 20ft up."

        How much heating do you plan to do? Where are you located? Units lacking a basepan heater are risky to operate in winter conditions especially snow. The pan will turn to solid ice and can burst the outdoor coil. During deforost cycles there will be a lot of water dripping into the pan.

        I have an electrical monitor on my units and can see when they defrost. Here in CT that happens alot in the winter.

  3. Expert Member
    Dana Dorsett | | #5

    Having it blow toward the walkway does a bit of double-duty by keeping some of the snow from landing there.

    Putting them on a stand on a condenser pad would be somewhat preferable to hanging them from the deck structure. The odds of hitting some harmonic of the deck & or framing at some modulation level is pretty high, and the low frequency noise induced will carry.

    Dripping water on them isn't a huge deal, falling icicles, snow, & snow avalanches are. If it becomes an issue, a mini-ceiling of weatherproof materials fastened to the joists above works fine, without resorting to one of these:

  4. raul4817 | | #6


    I can easily pour a concrete pad directly under the deck in option 1 or 3. If im correct the unit itself is 24" tall and per fujitsu requires needs to be elevated min. 2" off the pad. I just realized however that they are asking for 24" above the unit. that being said If place 2" off pad poured at grade I would have 15" to bottom of joists and 24" to underside of deck boards. I'm thinking 2" off grade is pushing it with snow. not sure if I could raise it a bit higher considering this. The snow fall would not fall directly on the unit since the deck is directly above it but there would be some snow in front.
    Setting the units off the side of the deck in option 3 would be a shorter run for the lineset and somewhat out of the way in terms of backyard aesthetics. My only hang up is that there will be a fence built prior to the adjacent walkway. The fence will be around 42" away from side of deck. Fujitsu is asking for 8" in front so I should be clear on that end.
    The second photo is ideally what I would be shooting for but this setup requires me to build a snow cover( not an issue) and would inch me closer to the proposed fence by 16" or so, still giving me more than 8" needed.
    Also I wanted to thank you for your insight over the past year. You had originally suggested the 18RFLCD and it was a good one in terms of price and efficiency. I had my duct design and load calcs done by a local mechanical engineer and now Im just waiting for the weather to break to finish the outdoor install. I recently had PV installed so Im anxious to see how this unit performs and when finances permit I would like to handle the 27K Btus needed for my 1st floor and basement. Still undecided on whether to to install another 18RFLCD+ a 9RFLCD or a single ARU24RGLX. but I cross that bridge when i get there.


  5. Expert Member
    BILL WICHERS | | #7

    Option 2 of your original options is probably least likely to have issues with amplifying any sound from the condensers. There have been several posts on GBA in recent months about noise from outdoor condensers coupling into the structure and being annoying, so that's a real concern that you should be thinking about.

    I agree with Dana that if you mount the condensers to the deck directly, you'll probably find that you'll have some annoying resonance somewhere that you'll hear. Murphy's law dictates that this resonance will be at is peak at whatever set of operating conditions you experience the most, which will maximize the problem.

    Pouring a dedicated pad for the units will solve the noise issue. Why not just set the pad so that the unit is slightly outside of the deck to avoid the clearance issues? You could still keep the unit low to avoid seeing the top of the condenser above the surface of the deck, but without the deck directly overhead, you won't have any issues making the clearance Fujitsu is asking for.


  6. Expert Member
    Akos | | #8

    Is your house brick veneer or double brick? With double brick, I've had no problems with wall mounted units. With brick veneer you do hear the unit a bit but nowhere near the annoying level I've had with units mounted to wood structure.

    I like to mount them about 8' in the air on the side of the house towards the back. This keeps it out of natural sight lines and can easily walk underneath (important here as houses are 2' to 3' apart). Even small roof overhangs do a decent job of keeping the snow off the units. You can see the 3 units along the wall bellow.

    If you are going to mount it under the deck, I would put it closer one of the edges with the fan blowing outwards. This would reduce the chance of just recirculating the air underneath the deck. Just make sure the snow berm you'll get around the deck won't end up blocking the unit.

    Line length is not a very big issue. You loose a bit of capacity, in the order of a couple of percent. The manual for your unit should show the de-rating.

    1. raul4817 | | #9

      Akos/Bill ,
      The house is double brick. So under the deck option seems to give me the most issues with clearances and recirculating the air under the deck but best for noise. I could place it as close to the edge but I'm sure a 2nd unit is coming sooner than later and with that I would have no choice but to go further under the deck with that install, increasing my chances of recirculating.
      What do you think of a modified option 3? I could come out from under the deck and go higher up off the ground. This side of the deck is actually going to have an outdoor kitchen so i will be enclosing my balusters like pic 2 so I can hide my propane tank, smoker, etc. In this scenario I could come even higher and the unit should still be out of my sightlines while sitting on the deck. I still have the fence in question but according to fujitsu's manual Im more than the 8" clearance specified.

  7. johns3km | | #11

    One a hot day with the ODU fan running full blast I wouldn't want to be sitting over them on a deck for noise reasons. Maybe you wouldn't be outside on a day like that but something to think about.

  8. Expert Member
    Akos | | #12

    You have perfectly good double brick wall, unless there is a good reason for the floor mount, you are just complicating life.

    Keep it simple and mount it on the wall.

    1. raul4817 | | #13

      I could mount on the brick wall to the side of the house. My issue with this is that is the neighbors walkway so I wanted to be considerate to them. If I go under deck the brick I cut it close on clearances and as others have noted recirculating the same air. If I where to go say 8-10' up on the brick that could work. It may complicate the original plan for lineset runs and building a snow cover is a bit trickier. The slab is really no issue since I have a cement mixer that can make short work of it. I measure last night for the lineset run to the side of the deck location and I am right around 40' .

      1. Expert Member
        Akos | | #14

        I've never had issue with snow buildup on wall mounts. You don't need a cover over it nor do you need to worry about the snow buildup as with a ground mount.

        As long as you stay on your side of the property line, I can't see what the problem is. Being between the houses keeps it out of sight, I rather not see the unit when sitting on my deck.

        8' up is an easy install. The hardest part is lifting the unit up, two guys on two ladders makes it easier. At that height also most of the standard gauge sets reach from the ground, easy to pressurize and evacuate. I wouldn't go higher than 8' unless there is a good reason for it.

  9. raul4817 | | #15


    Here is an old photo pre deck. The only space I can think of off the brick would be between the glass block window and double hung. This lines up pretty well with the closet I planned on using to fish the lineset up. This could work, I would have to run it by the wife but I think this is a good option.

  10. Expert Member
    Akos | | #16

    That works. When stacking the units make sure to route the drain for the upper unit's pan sideways so it doesn't dump water onto the unit bellow during defrost. This drain line might need a bit of pipe heat to not freeze up.

    Looks like the units could also fit side by side, one under the small window.

    Try to avoid locating them so the lineset or the units are visible when looking out the window.

    1. bfw577 | | #17

      He mentioend earlier that his unit has no drain pain heater. I posted my concerns in that comment as that pan is definitely going to turn to a block of ice. His profile says he is in IL where I would make sure I had a drain pan heater if I planned any winter use. I would definitely not mount one high up unless it has one.

      There was a post on here recently with someone having their pan turn to a block of ice due to not having a basepan heater. The outdoor coil can easily burst when that happens.

      I have an electrical monitor on my units and they defrost alot here in CT. Even with a pan heater I have had to chip some heavy ice out of the pan many times. Its not 100 percent effective.

      1. vap0rtranz | | #18


        Pan heater >> outdoor location, IMHO for cold climates.

        We have one and I've also chipped away at ice build-up twice. I wondered why the buildup happened, like if the unit wasn't defrosting enough (we have a 36kbtu Bryant multi-split that doesn't go into defrot very often until temps get down into the teens.) I'd assumed the defrost cycles would totally take care of the icing. Well, it doesn't. I have a theory that nobody has mentioned ...

        ... the outdoor unit INJESTS a huge amount of humid air in most winter locations. I noticed this one day while it was snowing heavily. Our unit is protected by a roof overhang, the prevailing winter wind comes in from the opposite side of the house as the outdoor unit, but I could clearly see snowflakes being sucked into the unit in large quantity. It looked like a giant vacuum :)

        Unless the poster lives in a dry cold climate (cold desert night), even on a day without rain/snow, and even if completely covered from rain/snow: there's got to be a large volume of humid air moving through the outdoor unit. It collects on the fins, condenses, freezes. Evidently sometimes in larger quantity than the defrost + pan heater can compensate for. So I'd not go without a drain pan heater in our climates.

      2. raul4817 | | #23

        I was originally concerned with this issue as well. After a lengthy back and forth with Dana, (Who seems to be the foremost authority here on all things Fujitsu) I have decided to move forward. I am completely aware of the issue and fairly confident that with some heat tape strategically placed I can monitor and keep this a non issue. Fujitsu has this unit rated to operate down to -5f and other members here have confirmed that it will work in even lower temps, but ice build up is something to be aware of. I have found this unit to meet my price point and efficiency expectations(on paper at least). I was also concerned with ducting this unit to service the multiple rooms on my 2nd floor, But after working with a local mechanical engineer who calculated my loads and designed my duct layout, I actually have some CFM to spare. I wont have it up and running till next winter so no way to tell if I made a poor choice till then. After a year or so of running the 18RFLCD I plan on changing my natural gas furnace over to one of fujitsu's mid static or an 18RFLCD+9RFlCD also rated to -5F to handle the other 27k btus needed for my 1st floor and basement. This number will be recalculated when i get closer to that since im planning on some retrofit work on these levels. I took a serious look at some of mitsubishis units as well as daikin but price and modulation won out. I have been warned by a local installer that fujitsu service in our area is bleak, but a risk I'm willing to take. My home will have 2 possibly 3 separate single zone ducted units so Im think the fail safe here is that if one units does have a hiccup I'm still producing some heat. I have put some thought into a wood stove in the event of a zombie apocalypse, but the grid here is pretty damn reliable so maybe just a few oil filled electric space heater will do.


  11. bfw577 | | #19

    Here is a good blog where the outdoor coil burst from ice bulging in the pan due to a lack of a pan heater.

  12. Expert Member
    BILL WICHERS | | #20

    This is a bit unrelated to the minisplit, but concerns your electrical service drop. It looks from those pics like the drop is touching, or nearly touching, your downspout. This is a bad thing because as the drop moves around in the wind, the downspout will slowly abrade the insulation on the triplex cable that comprises the service drop.

    One day the abrasion will make it through the XLPE insulation on the drop, and then you’ll either arc to the downspout and potentially start a fire, or energize the downspout if it’s aluminum which could zap someone. My recommendation would be to either have an electrical contractor come out and use a stand-off bracket to get the drop out farther from the house, or ask your electric utility to come out and put one of their protective sleeves (these are used to protect cables while work is being done) on the drop where the gutter is. Those sleeves are usually bright orange, so be aware of that.


    1. raul4817 | | #21


      The line I think you are referring to is actually coaxial cable from my garage mounted satellite dish and phone line from the pole, haven't got around to it yet but I will stand that off the downspout. The service drop comes in a few feet above that on a slight angle, I have a good 2ft" of clearance to the downspout. Tough to see from that photo.


      1. Expert Member
        BILL WICHERS | | #22

        Ah, ok. If you need to sleeve the coax, a split piece of sprinkler pipe works. In the utility trade, this is known as either “tree guard” or “squirrel guard”.

        Tree guard is a snap-on cover to protect the cables from tree branch abrasion. Squirrel guard is a loose-fitting tube that protects cables from squirrel chew (a major cause of outages) and can spin around the cable so that squirrels can’t stay on it. Both are sold in large sticks, so for your little gutter spot a piece of sprinkler pipe slit with a knife would be the easiest way to put some extra protection in place if you aren’t able to use a stand-off bracket.


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