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View Full Version : Buying an air compressor, need advice



Wanted1990SC
04-05-2009, 06:31 PM
I bought an air compressor from harbor freight. It's 120v and I got it for $138 out the door including taxes with a 20% off coupon. My dad told me that I should have got the 230v model because it runs cooler, uses less electricity and is more powerful. So I went and exchanged it and when I got it home, I noticed on the box that the SCFM ratings are actually worse! So did I make a mistake in getting the 230v model?

here are the 2 models.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94667

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93271

Any input would be appreciated.

old_coot
04-05-2009, 07:52 PM
You are comparing apples and oranges----the only thing that might run cooler is the electrical motor---but they are both 3 HP and since HP in electrical motors is a measure of the power (watts) they consume, I even have my doubts about that---but I would have gotten the 230 volt also since they don't require the big starting capacitors which can get quite pricy to replace if they go bad---and they go bad....the scfm ratings are for the compressors themselves and they are what they are ----depending on what you use it for both may be adequate or not................Dan

Wanted1990SC
04-05-2009, 08:11 PM
I am replacing worn out shocks on our 2006 Chevy Trailblazer. I will definitely use it to work on cars.

KMT
04-05-2009, 08:49 PM
You'll be fine w/the one you have now....by the time you outgrow it, if ever, it will need replacing anyhow :)

Mike Puckett
04-05-2009, 11:12 PM
I'd recommend taking it back and getting a Craftsman instead. I've got a 20 gallon at work that's run everyday for 25 years and I've only had to drain the condensate twice and tighten the belt in all that time. I've got a 33 gal Craftsman at home that's never hesitated in over 5 yrs. Both are 115V.

old_coot
04-06-2009, 09:08 AM
I've got a BrandX thats 15-20 years old and it gets a workout daily it has a 60 gallon tank and a 5 hp motor with a two cylinder compressor, I live where there is actually moisture in the air, I probably drain 5 gallons of water out of the tank each year, I have to run a dryer on the output to keep tools, blast cabinet, and paint guns working properly but the compressor sits in the corner and just does its job year after year---so it doesn't have to be a high dollar item to get the job done but a little attention is required to get the most out of them for sure.................Dan

KMT
04-06-2009, 10:46 AM
I'd recommend taking it back and getting a Craftsman instead.

That Sears IR/Craftsman 20 gal. (http://www.sears.com/shc/s/p_10153_12605_00989225000P?sid=BVReview) compressor sells for $500 today - he paid less than $150 for the one from HF (and I think this was his motive...) - he could buy three and wait for them to wear out and still spend less money :)

Everyone has a different budget and needs. Buy what fits yours best.

mi pajaro
04-06-2009, 10:49 AM
Those are what I call hobby compressors, good for the occasional weekend wrenching session, etc. For serious daily use in a dedicated home shop I wouldn't have anything less than a quality built, stationary 3HP (running) and 60 gallon tank or it's 5HP (running) brother like the Ingersoll Rand (http://air.ingersollrand.com/IS/modelComp.aspx/item/12885) SS3L3 or the 5HP SS5L5 (my choice). When I bought my SS5L5 they were USA made but someone told me they may be built overseas now and I can't confirm that.

I don't know if you are like me and fortunate enough to have a dedicated shop area to work in (or a cool wife) which changes what you can get away with buying. If you aren't that lucky what you have will be just fine. Remember NEVER run a compressor off an extension cord. Air hose is cheap and since your compressor is on wheels you can fill it off a dedicated outlet and move it to the job.

I know it is tempting but never buy PVC air hose, it is a complete pain to coil, uncoil and store. Rubber hose can be found the same place you bought the compressor and works tons better.

Oh and don't get caught up in the single vs. dual stage thing. Unless you are doing a lot of paint or other high volume work, single stage is fine. When I use my compressor I can use any tool I own and the compressor will fill and shut off while I am using the tool without me stopping work. Smaller compressors can't do that, but they are much less expensive, take less space are more portable, etc.

Wanted1990SC
04-06-2009, 10:59 AM
Mike, I was looking for a Craftsman on Craigslist. It seems like for a decent one I'd spend like $250 for it. I spent $138 for this with taxes and everything. I'm just strapped for cash right now. My dad has a craftsman horizontal that's 20+ years old. It still works, but there is a leak in the tank.

Dan, thanks for the info. I feel a little better now. But I still have questions about the SCFM. Is the 220v powerful enough to run an impact wrench? The impact wrenches I've been looking at say they require 5.0 SCFM @ 90 PSI. The 220v is only 3.5 SCFM @ 90 PSI. I bought this with the sole intentions on working on cars.

thanks again

mannysc
04-06-2009, 11:33 AM
ive had 2 of those the reed valve cracks in few months .
it wont keep up with the smallest of air tools .
it gets hot if run for more tan 20 minutes melting fan off of motors armature.

the pump has no bearing on rod it wears out fast and get loud and knocks .
its good for filling tires but not for air tools

when hot it wont start so go for the 220 volt if you do get one .
oh yeah harbor freight couplers leak real bad .

I go thru compressors fast doing parts at home . the belt driven pumps are better the coupler between motor and pump breaks on this model .

just a heads up from a 2 time owner of this pump 20 hrs and its toast.

but i do run mine 8 hrs a day . I now have a vw diesel rabbit engine connected to a 1.6 liter engine with exh pushrod removed that is now my pump makes one hell of alot of air I can run 6 air tools at a time now and keep 100 lbs pressure and it runs all day on 1 gallon of diesel other axle runs my generator I used the trans axle as a ptu for both yeah yeah home made junk but i only pay $4 a day for air and electricty.

well sorry to hyjack tthe thread just a heads up on the air pump under extreme use its not up to the task

Wanted1990SC
04-06-2009, 12:07 PM
ive had 2 of those the reed valve cracks in few months .
it wont keep up with the smallest of air tools .
it gets hot if run for more tan 20 minutes melting fan off of motors armature.

the pump has no bearing on rod it wears out fast and get loud and knocks .
its good for filling tires but not for air tools

when hot it wont start so go for the 220 volt if you do get one .
oh yeah harbor freight couplers leak real bad .

I go thru compressors fast doing parts at home . the belt driven pumps are better the coupler between motor and pump breaks on this model .

just a heads up from a 2 time owner of this pump 20 hrs and its toast.

but i do run mine 8 hrs a day . I now have a vw diesel rabbit engine connected to a 1.6 liter engine with exh pushrod removed that is now my pump makes one hell of alot of air I can run 6 air tools at a time now and keep 100 lbs pressure and it runs all day on 1 gallon of diesel other axle runs my generator I used the trans axle as a ptu for both yeah yeah home made junk but i only pay $4 a day for air and electricty.

well sorry to hyjack tthe thread just a heads up on the air pump under extreme use its not up to the task

Manny, you had two of the 120v models? So your saying that 220v won't run air tools like an impact wrench? if that's the case, then this is useless to me. :(

Btw...that's very cool what you did with the VW motor! lol

mi pajaro
04-06-2009, 12:09 PM
Mike, I was looking for a Craftsman on Craigslist. It seems like for a decent one I'd spend like $250 for it. I spent $138 for this with taxes and everything. I'm just strapped for cash right now. My dad has a craftsman horizontal that's 20+ years old. It still works, but there is a leak in the tank.

Dan, thanks for the info. I feel a little better now. But I still have questions about the SCFM. Is the 220v powerful enough to run an impact wrench? The impact wrenches I've been looking at say they require 5.0 SCFM @ 90 PSI. The 220v is only 3.5 SCFM @ 90 PSI. I bought this with the sole intentions on working on cars.

thanks again

I'm not Mike, but I can answer this for you...

If that is all you can afford I can relate and you can just replace it later, that is what I did. With limited (weekend) use and waiting for it to cycle instead of letting it run continuously you will get many miles from this compressor. My dad still has the 15 or 20 gallon Craftsman laydown we used (abused) over 20 years ago and it is still ticking because we never let it get too hot or run continuously. When I bought a house with a shop and bought my SS5L5.

I'm not sure I would buy a used small compressor because you don't know how abused it has been.

The motor has nothing to do with running an impact wrench, it is all CFM and PSI which comes from the tank when the compressor is running. Most air tools are rated at 90 PSI and the recommended CFM rating is listed on the box. I would return the 220V model and get the 110V because there are 110V outlets everywhere and a 220V outlet would need to be wired in your work space.

Mike8675309
04-06-2009, 12:18 PM
Mike, I was looking for a Craftsman on Craigslist. It seems like for a decent one I'd spend like $250 for it. I spent $138 for this with taxes and everything. I'm just strapped for cash right now. My dad has a craftsman horizontal that's 20+ years old. It still works, but there is a leak in the tank.

Dan, thanks for the info. I feel a little better now. But I still have questions about the SCFM. Is the 220v powerful enough to run an impact wrench? The impact wrenches I've been looking at say they require 5.0 SCFM @ 90 PSI. The 220v is only 3.5 SCFM @ 90 PSI. I bought this with the sole intentions on working on cars.

thanks again

The HP rating is on the electric motor turning the crankshaft of the compressor. Typically this implies the size of the compressor, but in this case, I'd say the 220v model has a smaller compressor or different , or there is a misprint. It appears these may be direct-drive units.

If the tool says it needs 5 SCFM at 90psi, well then that's what it's gonna need.

The main difference between 220v and 115v, is the electric motor isn't as stressed when running 220 vs 115 if they both are putting out the same HP. It has to do with electrical efficiency.

Wanted1990SC
04-06-2009, 12:20 PM
Yes, I was just buying this to get me through a few projects and that's it. I was thinking of putting it up on craigslist and with next year's tax return, get a real compressor like a Cambell Hausfield or something. My neighbor is an electrician and he is going to help me wire up my garage, so that's not a big deal.

I guess where I'm getting confused is on the PSI and SCFM and how it effects perfomance with air tools. Here are the specs on the 220v compressor.

230 volt, 60 Hz; Air delivery: 3.5 SCFM @ 90 PSI; 8.8 SCFM @ 40 PSI

The impact wrench I was looking has these requirements

Air requirements: 5 CFM @ 90 PSI

mi pajaro
04-06-2009, 12:22 PM
The HP rating is on the electric motor turning the crankshaft of the compressor. Typically this implies the size of the compressor, but in this case, I'd say the 220v model has a smaller compressor or different , or there is a misprint. It appears these may be direct-drive units.

If the tool says it needs 5 SCFM at 90psi, well then that's what it's gonna need.

The main difference between 220v and 115v, is the electric motor isn't as stressed when running 220 vs 115 if they both are putting out the same HP. It has to do with electrical efficiency.

Agreed. :)

I have seen compressors like these two that seem like one should be better than other model(s) but weren't and close inspection typically revealed why. My compressor is actually rated for better flow than the two stage of the similar model.

Mike Puckett
04-06-2009, 02:56 PM
I can certainly understand wanting to spend as little as possible. I'm not real confident in some of Harbor Freight's stuff though. I've got one of their pancake compressors and it lasted a year until the electrical contactor burnt out. They sent me another one under warranty and it lasted a year and burnt out, too, but at least they covered it. And as Manny said, their air fittings tend to leak really bad. The brass ones are better than the steel ones but they still leak. Good luck.

old_coot
04-06-2009, 04:03 PM
the SCFM rating on a compressor is its continuous output at that pressure...Can it supply the amount of air to run the air tool----Yes --but not continuously---only is short spurts and then it will have to catch up and you can do another spurt.....I am not in any way recommending this compressors---I look at specs and then make what I hope is an informed decision...the reed type compressors are less durable for sure....I've had good luck with the one in the shop and I have a couple that we carry with us to the drag strip and other work sites---but those only get occasional use--so far so good..............dan

Wanted1990SC
04-06-2009, 04:09 PM
Dan, that's what i lived with at my dad's house for years. We'd let the compressor run, then use the air tool, let it run again and use the air tool. lol....sad to say I'm used to it. It got worse too as the air tank sprang a leak. Maybe this will get me until next year since I already have it in my garage.