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Thread: "Portable" air conditioner vs dehumidifier

  1. I have been running a portable AC this summer here in Florida in a two car garage sized shop. It is a combo AC, dehumidifier, heat pump. So far I like it very well. I cut a hole about the size of a dryer vent in the wall rather than use the existing window. The portable unit was a minimal investment up front, but a mini-split might have been cheaper in the long run. I don't expect to be here too many years, so I am okay with the cheaper up front cost and higher ongoing costs. In my case it might actually wind up actually being cheaper depending on how soon we move.

    AC is pretty important here and I oversized it for the square footage.

  2. #17
    I would just do the mini split myself.

    Not much impact on the wall as far as cutting holes goes. No impact on framing.

    Or just muscle through it. We're almost done and will be whining about the snow soon enough.

    It has been stupid this summer. I really want AC for the shop next year, the quote I got was $17k and I figure it'll cost another $800+ a month to run.

  3. #18
    Join Date
    Mar 2003
    Location
    SE PA - Central Bucks County
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    65,688
    Quote Originally Posted by Martin Wasner View Post

    Or just muscle through it. We're almost done and will be whining about the snow soon enough.
    MiniSplits are also very efficient for heating, too...which is the primary reason I installed mine because of being all but full time in the shop now and the very high cost of resistance heating. The AC has been a sublime benefit over and above that need! Out electric bill this summer has barely blipped from my using the AC daily out there, too. I was expecting a reasonable cost, but it's almost nothing.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  4. #19
    I just got it at the beginning of the summer so I don't know what the longevity of it is going to be, but I have been using the top model Delonghi portable AC / heater from Costco and I have been very pleased with it.
    A two hose unit would probably be better but I really have no complaints about the one I have.
    Operational situation is about as harsh as it gets.
    I am in the Dallas, Texas suburbs, two car garage no insulation, exhausting under the garage door so air infiltration is horrible.
    The unit pulls the temperature down 10 degrees below outside temperature and the garage "feels" conditioned.
    I can work comfortably enough until the temperature hits 88-89 degrees in the garage and then I begin to sweat to much.
    All things considered I think the portable AC is working great.

    As a side note we just hauled the unit with us when we went to Wyoming to help out mother in law, it was awesome being able to do that.

  5. #20
    Join Date
    Jul 2017
    Location
    Abilene, TX
    Posts
    109
    A mini Split was the way to go for me, I live in West Texas and it does get hot (104 is not un common) and very cold ( I have seen 0 degrees ) the humidity varies. I have a 400 sq ft two car garage that is insulated as well as the two Garage doors. I bought a PioneerMiniSplit heat pump/AC $700.00 12000 BTU this summer.
    i am very pleased with the unit it is very quiet on the high fan speed. I can not say about electric efficiency because we have free Electric power from 20:00 until 0600. It has Wi-Fi connection that I can control the unit from my smart phone.
    I schedule it to come on at 20:02 every night and shut down at 05:45 With an (OAT) out side air temp at 90 degrees and the Ac off all day the garage will warm up to about 85 degrees. With same temps OAT 90 degrees at night the temp in garage in the morning will be about 69 degrees with the thermostat set at 62 degrees.

    I say will I wish I had bought the 18000 BTU unit however everyone I spoke to about sizing it at 12000 btu’s said it would be adequate. It takes about 45 minutes bring to the temp down to 78-79 when the OAT is 90 plus.

    I have a Gree MiniSplit in another room in the house that is a 22000 BTU unit, cooling and heating a 900 sq ft room
    that unit I had installed for about 3k two years ago. It cools and heats very well.

    The Pioneer I installed my self and I am not an AC guy I do have a friend that is and I used his vacuum pump to pump the system down, I then let it set to insure I had no leaks for a couple of hours. The unit comes precharged with the 410A
    introducing the precharged gas is simple as turning a hex key that opens the valve to charge the line set and the evaporator.

    The install was easy and mine is 120 volts the 220 unit draws the same wattage.

    over all I am happy with the mini split.

    Lane
    I hope this helps.
    Last edited by Lane Hardy; 09-27-2018 at 2:45 AM.

  6. #21
    Join Date
    Jul 2017
    Location
    Prairie Village, KS
    Posts
    397
    I went with a Pioneer unit as well and am very happy. Now I just need to insulate my damn ceiling.

  7. #22
    Update:

    I finally gave up on a regular dehumidifier. Just put way too much heat into the garage. Bought a 9k BTU Pioneer Minisplit and installed it (and took the electric resistance heater down). The cost of the minisplit, vacuum gauges, a vacuum pump, a flaring tool, an A/C disconnect box, and misc wiring, etc, was ~$1k.

  8. #23
    Join Date
    Mar 2016
    Location
    Millstone, NJ
    Posts
    1,590
    split/heatpump and a dehumidifier together will be your best bet.

    Dehumidifier works like a ac unit but produces more heat than cooling so it will raise space temp but it will also pull moisture better than a split.
    A split would pull moisture out of the air the same way it would in your house. but it would suck to run it when your not in the shop or when its 72 and humid

    If you decide on a heatpump it will save you money over electric heat but will increase the price of the split. The other thing I would mention here is if you go with a heat pump size it for heating not cooling. They are more efficient at cooling than heating. Depending on your shop size and insulation level it may or may not make a difference in the size of the split.

  9. #24
    Join Date
    May 2008
    Location
    MA
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    2,255
    Quote Originally Posted by Dan Friedrichs View Post
    Update:

    I finally gave up on a regular dehumidifier. Just put way too much heat into the garage. Bought a 9k BTU Pioneer Minisplit and installed it (and took the electric resistance heater down). The cost of the minisplit, vacuum gauges, a vacuum pump, a flaring tool, an A/C disconnect box, and misc wiring, etc, was ~$1k.
    A great solution. But depending on where you live I would not throw away the electric heater just yet. Cold temperatures (high differential temps) dramatically reduces the capacity of electric heat pumps, so in cold climates an additional boost is often needed.

    I have used humidifiers for years for certain spaces, and believe the split mini reliability will be much better as another bonus.

  10. #25
    To dehumidify, you can run the electric heater against the mini split on air conditioning mode.

    It sounds wasteful but it'll improve the A/C's dehumidifcation efficiency dramatically when it's cool outside. As I said earlier, the coldest hours of the day are usually the most humid. It's why dew forms in the early morning---and when rust forms on your tools...

  11. #26
    Join Date
    Nov 2003
    Location
    Central North Carolina
    Posts
    1,830
    Actually, Bob. The humidity, or amount of moisture in the air remains the same, but in the cooler morning hours the dew point changes because of the cooler temperatures. Cold air cannot hold as much moisture as warm air can. The point at which moisture held in the air must be released as the air cools is the dew point. Same amount of moisture, but it must come out of the air because at that cooler temperature the air can no longer hold that much. Coolig the air reduces the dew point which causes the moisture to condense out of the air as water droplets. A dehumidifier does this to get moisture out of the air, but then returns the heat removed back into the air, plus the heat created by the mechanical mechanisms within the dehumidifier. An air conditioner does the same thing, but doesn't return the heat to the inside air, thus cooling the inside air. All of it's generated heat as well as the heat removed from the inside air is exhausted to the outdoors.

    So it's really the dew point that is important, and keeping it well below the desired air temperature is what is important. At 75 degrees with a dew point of 65 degrees both you and your machines will stay very dry. If the dew point and the temperature are both 75 degrees, moisture will begin condensing out of the air. If the dew point is 78 degrees and your room temperature is 75 degrees it will likely be raining on you.

    Charley

  12. #27
    Join Date
    Feb 2018
    Location
    N CA
    Posts
    1,279
    I may be incorrect here, but it is difficult to compare the dehumanizing operation of the conventional "split" system and a mini-split heat pumps (mshp). I look at the split as a ducted unit. I run Fujitsu mini-splits. I was the Fujitsu Rep in the six N Eng. States for 14 years. With the variable speed inverter units what is important to you mostly is not how high the unit will go, but how low. Yes, if you allow the mass of the shop to build the heat, it will take time to pull it down, but you will get there. The dehu feature on my units is the "Dry" mode. In Dry, the unit will keep the evaporator (indoor) units coil just cold enough to condense the moisture out of the air. I don't see that feature here in CA but I sure did in MA and the comfort and economical operation were just splendid. If you can do it, go with the mshp. You will not be sorry...assuming a good install that is!

  13. #28
    Quote Originally Posted by Jack Frederick View Post
    I may be incorrect here, but it is difficult to compare the dehumanizing operation
    The installation was tricky, but not dehumanizing...

    You're right, though - the one I bought is a heat pump with a separate "dry" mode. Glad to hear it was the right choice!

  14. #29
    They are both extremely useful inventions. Personally, I use a Frigidaire – FAD954DWD portable unit. This is because I enjoy its compact shape, making it easier to move to different rooms.Air conditioners remove the hot air from your home, while dehumidifiers decrease the level of humidity in the air. And when looking at dehumidifier power consumption vs air conditioner,to me, it does seem that a dehumidifier is best,
    Last edited by Nick Denver; 06-02-2019 at 4:31 PM. Reason: Spelling

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