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  1. #1

    AC Compressor Placement in Garage

    Hello, I'm new to the forums as a poster but have been reading for months!

    I live in Northwest CT. I'm about to install central AC into a 1940s stone house. All new ducts and equipment. I'm going with the Carrier Infinity 21 SEER unit, 4 ton. It's a smaller house (1800 sq ft). My question relates to placement of the outdoor compressor unit. I have minimal foundation landscape as the stone is attractive and I don't want a giant AC unit near the house. My 3 car garage is mostly underground and is NOT under the house, there is a roof over the garage which is essentially at ground level. The garage stays basement temperature all summer (60-70s). CAN I PUT MY COMPRESSOR INSIDE THE GARAGE? This is a weekend house, so the unit will only be used when the house is occupied on weekends. Any experience doing this? Why can't I have the contractor put the unit in the garage? I sent my contractor an email and have not heard back yet. He is supposed to start work in 3 weeks. Much appreciate any feedback or comments!

  2. #2
    Join Date
    May 2006
    Location
    Philadelphia, PA
    Posts
    1,384
    Cannot put in garage. There must be adequate air for ventlation. All the heat from the house and vapor compression action will be remived by the condenser coil

    Looks like a very big unit for your house suze and climate

  3. #3
    Thanks. What is the definition of "adequate air"? Is there a formula that says a certain amount of cubic feet or is it just outside is outside is outside?

  4. #4
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,625
    have you considered geo thermal .that way no ugly condenser ,although i think they are a beauty'$$
    We really need change now

  5. #5
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    A stone house that size in that climate shouldn't need more than 2 tons. Stone has a TON of mass so you only need ot cool to the average daily temperature on the hotest day which will be about 80F. Guess how much cooling you need to go from 80F to 75F. Not much. Oersizing in a stone house will make it use more energy and have humidity contorl problems.

    I think you need ot make you contractor do a load calculation. You can cool a pre-war stone house as large as 4000sqft with 4 tons in your climate depending on windows. I doubt you need more than 2 tons. Guess what, that's 1/2 the airflow and half the ductwork and the unit will be a lot less expensive. A 2 ton condenser will also be a little smaller too.

    No, garage won't work. Too hot.

    As mentioned, the only other options are geothermal, or a ducted VRF unit. That you could install in your garage. But they aren;t cheap. Probably more tha nhte Infinity system.

    It would be a shame ot put in a awesome Carrier Infinity system (I have 2 and love them) and have it be noisy, drafty, and short cycle because it's oversized. a 2 ton unit (if that's all you need) will use about 20% less energy than a 4 ton just because it runs longer.

  6. #6
    Join Date
    Jan 2008
    Posts
    2,001
    You have to tell us why you want to go with a 4 ton unit.
    It sounds like it will be GROSSLY over sized.
    And that will be nothing but trouble.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  7. #7
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,320
    Quote Originally Posted by xtenson View Post
    Thanks. What is the definition of "adequate air"? Is there a formula that says a certain amount of cubic feet or is it just outside is outside is outside?

    Air cooled condensers require anywhere between 600-1200 cubic feet per minute per ton, with 1000 CFM per ton being average. So, doing the math, if you have a 25 x 25 garage with an eight foot ceiling, that's 5000 cubic feet, meaning a four ton condenser in this garage with a closed door will turn over the air inside two minutes. Meaning the ability of the air in the garage to act as a sufficient heat sink for the condenser goes to pot quickly. In other words, keep the condenser outdoors, and locate it on a side of the house least offensive to you.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  8. #8
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    There's a more simplistic way to look at it. IF it's a 4 ton unit (which I'm very confident is oversized in your climate), lets say it is and you average heat being rejected is 24k BTU. So you are now heating your garage all summer. How wil it be ventilated to remove that heat? Lets say you add a wall louver at the ground level and install several roof turbines to get at least 800CFM of airflow in there. You mgiht have a chance. Keep in mind that the garage will rpobably run about 10-15F hotter on average than the outdoors depending on buidling construction so you'll lose on average maybe 10% effciency over the whole season, or about 2 SEER on that XL20i.

    We actually have several commercial package rooftop units located inside a building for various reason...some good and other not good reasons. In summer it's almost 120F ambient in there and there are some chemical fumes too. They don't last as long as it it's on the roof. But then again, on the roof they'd be exposed to cooling tower drift.

    Is it a good practice no. Can it be done. Yes, with adequate passive or active ventilation. Could it affect the warranty? Maybe if it gets above 120F in there or it's too close to a wall. But if all clearances are met and it operates within the outdoor temp limits, I can't see why it would. Will it reduce effciency and possible equipment life. Maybe.

    Should you do it? Do you still have original wood windows on your home? I only ask because if you've put vinyl replacements in there, unless they are high end MArvins, then who care what a condenser looks like, your already negatively altered the appearance of your home by putting inferior quality product in there. What's the difference. Sorry to be blunt. But improperly mounted fake shutters and most replacement windows ruin the appearance of a home far worse than a AC unit along the side of a building taht can easily be obscured with properly placed shrubs and landscaping. You could even pick a brand that more closely matches the stone. If yellow/ brown stone, get a York. If grey, get a Carrier, Trane, Lennox or Goodman.

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