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Thread: Large tank air compressor vs smaller high output one?

  1. #1
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    Large tank air compressor vs smaller high output one?

    I'm looking to upgrade my air compressor. Currently I have a 4gal dual stack Campbell Housfeld that has served me well. But it's not all that powerful, leaks air, and is annoying to move around since it doesn't have wheels or anything. It works, I'd just like something better.

    So it would make sense to get a big tank "shop" compressor. I do have a decent sized shop and could probably fit it in. But we have a tiny house with no storage space, so a lot of stuff ends up in the shop as overflow. I guess what I'm saying there is that I try not to waste space.

    I'd like to have at least one portable compressor so I can haul it over to friends houses to help them with nailing or whatnot. But the one I have does serve that purpose.

    My question is, if CFM numbers are similar, what reason is there for a big shop tank compressor other than the fact that the compressor won't have to run quite as much? I can get a Dewalt refurb 4.5 gal high-output compressor for $230 that does the same CFM as the 20-40 gal big tank ones in my price range. While it would have to run a lot more often, it's also a lot smaller and has wheels for transport.

    In general, my compressor use is mostly for framing/brad/finish/etc nailers + random use of impact wrenches, die grinders and whatnot. I'd like to be able to use a spray finish setup at some point in the future. But that's a ways off and I don't have anything set up for it at the moment.

  2. #2
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    Josh,

    Depending on what you will use this for, you have to be careful on the duty cycle of the compressor. The better, larger compressors are rated for 100% duty cycle. I doubt the small Dewalt is rated for that duty cycle. Another advantage is the larger compressors can be oil lubed. These are much quieter to run then the non lubed types of smaller compressors.

    If you get a verticle tank compressor in the 30 gallon range with oil lube you would be far better off. Sort of the best of both worlds with some portability and decent capacity.

    just my $0.02

  3. #3
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    Josh...another consideration as to large versus small is what sort of tools you use, or plan to use in the future. Air sanders and wrenches require a larger reserve of air. A small receiver will empty quickly, causing the pump to work extra hard. This can lead to early failure. I have a PC side stack similar to you CH. Changing a tire with my impact wrench was an exercise in patience, waiting for the tank to refill. Take a look at the usage charts on the compressors at the borg.
    two more cents,
    Mick

  4. #4
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    You need to look at the scfm consumption rating of your tools and size your compressor so that it has more scfm than what is needed by the largest tool you have. Otherwise the large user tool will use air until the low pressure setting is reached and turn on the compressor, if the tool uses more air than the compressor can pump it will never shut off until you quit using the tool. The only advantage of a small compressor with a big tank is that the compressor can get ahead of occasional use of tools and not run all the time if the down time i long enough.
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  5. #5
    I have a 6hp 60 gallon compress, sounds great, the problem is the duty cycle is only like 45%.

    So as was stated watch for the duty cycle.

  6. #6
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    Compressor size really depends on your intended tool usage. For a good general purpose compressor for home I have a 28 gallon upright campbell hausfeld, its an oil lubricated pump also. I'd stay away from oil less compressors as they are very noisey (otherwise fine). I rarely run out of air, good little compressor for the money.

  7. #7
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    Thanks for the info so far folks!

  8. #8
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    Thinking outside the box....er house

    You might be able to build a shed like cover for the big tank compressor if you buy one, on the outside or backside of your garage. Depending on how your neighborhood restrictions may go, It can save you floor space for sure.

    Still the footprint of a vertical 5hp tank compressor is not alot.

    One advantage of putting it outside is the reduction of noise. Easy to put some insulation in an exteral attached cover so it doesn't bother the neighbors too.

    Just a thought.

  9. #9
    A big tank also gives the air someplace to cool off, which allows the water to turn from a vapor to tiny droplets, which can settle out to the bottom of the tank. All a big plus for spraying paint, etc.

  10. #10
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    Josh, how are you liking that big shop now? Have you done any upgrading? I know the house is small, but the shop is big.

  11. #11
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    Quote Originally Posted by David Helm View Post
    Josh, how are you liking that big shop now? Have you done any upgrading? I know the house is small, but the shop is big.
    The shop is great. It's a bit different than when you last saw it, we've added an "upstairs". But I really enjoy having the space. Though given the amount of house storage that ends up in there, I'd happily trade some of it for a larger house.

  12. #12
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    Quote Originally Posted by Stephen Cherry View Post
    A big tank also gives the air someplace to cool off, which allows the water to turn from a vapor to tiny droplets, which can settle out to the bottom of the tank. All a big plus for spraying paint, etc.
    THAT is a pretty good piece of info that I was not aware of.

  13. #13
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    I picked up a used Craftsman 2 HP 20 gal tank unit today that must be about 25 to 30 years old, but seemed in really good shape. It is an oiled 2 cyl compressor and the noise level is much bettter than my Porter Cable pancake. It does not have any after cooling, but a lot of the newer larger units do have the after cooling ahead of the tank that will help cool and drop out the water. A dryer and oil removal should be provided for any oiled compressor ahead of paint sprayer.

  14. #14
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    After cooling can be done by using copper pipe for some distance after the compressor tank and before the Filter and regulator. One of the upgrades I am planning is to do just this. About 20' of copper will definately cool the air and pull most moisture out. Having the filter/water sepeartor on the tank has proven to be a waste of effort for me. YMMV.

  15. #15
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    Marty is correct. If you put the filter/seperator too close to the output point of the compressor the warm air will hold the water and it will go right through. Once it cools in the lines along the walls, you get water vapor collecting at the connection point where you plug in your hose.

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