Compressor in warm place, hose going to cold place - issues to consider?

[Lewis Cobb]

Hi Folks -
My mind is wandering onto the ability to have compressed air in my garage and workshop that is an add-on to my garage. There's no room to put a proper compressor in either, but I can locate it in the basement of the house and run the airline to the garage wall that's common with the house.

In order to get to the workshop however, I have to travel up the wall of the garage, into the attic and then back down into the workshop. The attic is basically outside as far as temps go, and there's no easy way to keep the line under the insulation even though both the attic and garage are insulated. Either way, the garage is unheated anyway and can get quite cold. It will hit freezing at times during the winter, but not often.

What are the issues here to think about? I would imagine there's some serious condensation that's going to happen in the pipes when the warm moist air hits the run that's external to the basement of the house, but is it enough to deal with using a water trap, or am I setting myself up for torment ? It goes without saying that I better have a good grade in the runs so that the water can run back into traps I guess. I've seen these dessicant air dryers but I'm a noob with air systems and not sure where they apply - hence this posting

I can't see any spraying operations, but would run air grinders etc. as far as "heavy cfm" goes.

Thanks for the advice and tips, even if it turns out to be "don't do it !" -

Cheers,
Lewis

[james glenn]

I don't know too much about this, but I do know that when you go from cold to warm you get condensation (think ice water in a glass in the summer)
but the opposite way isn't an issue. At least with heating systems and water piping.

The rest I leave to those with more knowledge than I.

[mike wacker]

James,

You have it backwards. The atmosphere's ability to hold water increases with temperature. Hence the terms relative humidity and dew point. As air cools it "relative humidity" percentage increases. When the air gets cool enough to reach its maximum capacity to hold mositure (i.e. relative humidity of 100%) the moisture starts to drop out of the air and you get condensation or dew. This temperature is what the weather man is refering to when he says dew point. The condensation on the glass of ice warter on a warm day is the Warm moist air being cooled and "dropping" its moisture on the glass.

So now that I have hit the play back button from Earth Science class too many years ago the issues Lewis needs to consider are probably best addressed with experimentation. Run it with out any water traps or the like, drain the receiver (air tank) regularly and I bet you'll do fine. If you start having to deal with ice BB's (don't ask, but you'll know) then looking into dewatering one way or another might be of interest.

On another note a separate reciever in the garage might serve two purposes. Reducing "line losses" from you delevry hose and it might act as a moisture collector. Large compressed air systems in large industrial plants use this remote receiver approach all the time. Drain it regularly too if you try this. You can get a small air tank from a car supply shop like NAPA or mail order one from someone like Harbor Frieght. It's a portable tank that you fill up with your compressor and then carry out to where ever you need a relatively small amount of air but not enough hose to reach. If you found a pooched air compressor with a bad head you might get the receiver for free.

[james glenn]

James,

You have it backwards. The atmosphere's ability to hold water increases with temperature. Hence the terms relative humidity and dew point. As air cools it "relative humidity" percentage increases. When the air gets cool enough to reach its maximum capacity to hold mositure (i.e. relative humidity of 100%) the moisture starts to drop out of the air and you get condensation or dew. This temperature is what the weather man is refering to when he says dew point. The condensation on the glass of ice warter on a warm day is the Warm moist air being cooled and "dropping" its moisture on the glass.

So now that I have hit the play back button from Earth Science class too many years ago the issues Lewis needs to consider are probably best addressed with experimentation. Run it with out any water traps or the like, drain the receiver (air tank) regularly and I bet you'll do fine. If you start having to deal with ice BB's (don't ask, but you'll know) then looking into dewatering one way or another might be of interest.

On another note a separate reciever in the garage might serve two purposes. Reducing "line losses" from you delevry hose and it might act as a moisture collector. Large compressed air systems in large industrial plants use this remote receiver approach all the time. Drain it regularly too if you try this. You can get a small air tank from a car supply shop like NAPA or mail order one from someone like Harbor Frieght. It's a portable tank that you fill up with your compressor and then carry out to where ever you need a relatively small amount of air but not enough hose to reach. If you found a pooched air compressor with a bad head you might get the receiver for free.

Yeah, Yeah smarty pants.

You are right, not sure what I was thinking this morning but you are correct. That is why it happens on the outside of water lines. duh.

My bad. Guess I don't know much about anything today.

[George Clark]

Lewis,

I think you may have a good situation, actually. Since the air is quite warm when leaving the compressor and must cool in order for the water vapor to condense you will have a very efficient cooling system in the winter and due to the length of the run should work fine in the summer to give you very dry air in the garage. Just keep the pitch of your lines so the moisture will drain back toward the compressor as long as possible, use iron pipe or copper for safety and heat transfer and avoid and low spots or traps in the cold areas. In the garage I would install a water separator/filter and a regulator (I use combo units) with a drainable moisture trap below the regulator. My guess is you'll be unlikely to ever see much moisture in the garage. Be sure to drain the compressor on a regular basis. I would also consider wiring the compressor so it is convenient to shut it off when not in use. A running compressor with a broken air line is not a good thing. TP Tools has some good info on running air lines. Hope this helps.

http://www.tptools.com/StaticText/ai...ng-diagram.pdf

George

[Lewis Cobb]

Thanks for all the great info. I have also come across a few websites that have explained the air line routing, air cooling, condensation etc. in great detail for a newcomer like me. (about-air-compressors.com). The concept of a receiver tank in the garage some distance from the compressor in the basement is a good plan-B too.

The only hitch I can see at the moment is that the line running from the compressor to the garage is going to be about 50' long - and most of it will be either horizontal, or have a VERY slight grade back towards the compressor. Before it enters the garage it will have to go vertical for about 6" and then horizontal out through the wall of the garage. The vertical will prevent any condensation from getting into the garage, but there might be a chance of standing water in the pipe somewhere in between. If I use copper, that won't be a problem from a leakage point of view, but it might blow water up into the garage when there's a draw on the system. Maybe the receiver could help with this in the garage if so. In any case I'll check what's possible for a grade over that 50' run. The pipe is going to have to travel over 3 rooms - all of which have a suspended ceiling before it gets to the garage wall, and the floor joists are running the wrong way - I can't easily make use of the 12" depth of them, just the space between the suspended ceiling and the underside of them.

What size line should I be thinking about here from the compressor to the garage? 1/2"?, 3/4" ?

Thanks
Lewis

[Greg R Bradley]

I'm trying to figure out what compressor would have a noise level that would be acceptable in the basement of a house.

[Lewis Cobb]

Greg - I'm sure there's some ultra high end thing from some far off place like Germany that costs 20-30,000 dollars, but as you implied, most aren't. It's sort of the less of all evils for me. There's only 3 of us in the house and it's not a daily use thing so I think my wife and son won't object too much. As suggested, a power switch to shut the thing off until the next time it's used will be a part of the installation for sure.

I've got a real head-banger compressor that a buddy of mine loaned me a while back - it's sitting in the corner of the garage at the moment, but I'm going to run a test with it in the basement sometime this weekend. Just to see, before I start further down the road trying to figure out a way to run the lines. And on that note I might be up the creek anyway, as I was looking at the situation again this morning before I went off to work, and it might be impossible to run a line without trapping some moisture in the portion of the line that's in the basement. Then, when there's a draw for air, it sends some water shooting out. I don't want that.

Are there plastic lines that can be used for this application if the hard piping option does not pan out? Snaking something along through the floor joists might be a way to go if so. I have engineered I joists in the house and there are knockouts that could be used for that purpose.

In the end, if it looks unworkable, too noisy, etc. I'll give up on the idea. But there really is no room to keep a decent sized compressor in the garage or workshop. I have heard of people shoving them into the attic of the garage but I don't like that idea for a lot of reasons.

Anyway, thanks again fellows for the suggestions and comments.

Cheers,
Lewis

[Kevin Neal]

What size line should I be thinking about here from the compressor to the garage? 1/2"?, 3/4" ?

What is your total length to get from the compressor to the garage? What tools do you plan to run (air grinder, sand blaster, etc)? What pressure does your air compressor usual run?

If you'll give me your best guess on the answers to those questions, I can run it through some flow modeling software I use and let you know the pressure drops for different line sizes.

Have a great day. Kevin

[Callan Campbell]

I've had an underground air line to my unheated garage for about 20 years now. Compressor is in my basement . I have a standard 1/2" NPT ported air filter and regulator in the garage. I rarely get any water out of the filter. Never had an issue with ice yet. I run a feeble propane "tube" heater in the cold months if I'm going to be out there for awhile, but the performance of my air line doesn't seem to change year-round.

[Callan Campbell]

I'm trying to figure out what compressor would have a noise level that would be acceptable in the basement of a house.

My antique Saylor- Bealls 3/5 HP is very quiet since it's old industrial cast iron 2 stage . Even the intercooler between the 2 pistons/ stages is cast iron. Since it's pulleyed for a slower speed operation with a smaller 3HP motor instead of a higher output set-up with the larger 5 HP motor,it's spinning at less RPMs and a quieter operation too. It replaced a noisy old Sanborn single stage compressor that was at the limit with regards to basement noise levels. For any basement shop, you want a slower RPM unit to help keep noise levels down unless you can build a noise reducing enclosure for a noisy unit. Spinning the pumps faster to get more power out of a small unit is a common trick with compressor builders. Getting an accurate dB level for a given store unit, before you buy it, is probably hard

[Lewis Cobb]

Hi Kevin - Thanks for the help.

Well I don't own a compressor yet - just have the head-banging pancake that I borrowed from my buddy so I can't tell you what the "usual pressure" would be - I just have not done a whole lot with it. One thing I learned very quickly though - I am not buying an oilless "air nailer" compressor - I tried to run a little die grinder to clean up a few pieces of steel that I wanted to practice welding with and the poor unit was going 100 miles an hour and the grinder was going at about 4 rpm !!!

I will probably look at a 60 gallon unit and run it at 90-100psi as that seems to be a nominal pressure that people used (based only on some digging around on the web).

As for the hungrier tools - a die grinder (small) is about the max I can see at the moment. Mind you, I wouldn't mind having a little sand blast cabinet but I know they are real hogs for air, so that might be a no go - you sound like you might know what these things consume though. If I was to rig up a small tent in the garage in the summer I might try spraying sometime, but I really don't have an ideal place to spray and prefer to hand finish things as far as woodworking goes. Probably goes without saying but I am the only one using the tools so there's never more than one operational at a time.

As for distance - I can tell you that fairly accurately. It's probably about 70 feet in the basement before it enters the garage. From there I can connect right at that point, but if I decide to run it to the workshop at the back of the garage - add another 40 feet. I'm starting to think that's a pretty long distance, sort of like blowing through a 110 foot straw

Anyway, let me know what comes out of your magic flow software.

Thanks !
Lewis

[Lewis Cobb]

I've had an underground air line to my unheated garage for about 20 years now. Compressor is in my basement . I have a standard 1/2" NPT ported air filter and regulator in the garage. I rarely get any water out of the filter. Never had an issue with ice yet. I run a feeble propane "tube" heater in the cold months if I'm going to be out there for awhile, but the performance of my air line doesn't seem to change year-round.

Funny how these projects quickly spiral out of control.....now you have me thinking about the shed in the backyard that I always wanted to build and how to T off the airline and run it out there too......*sigh* good thing my wife does not check into these forums.....

[Kevin Neal]

It looks like you will be fine running either 1/2" or 3/4" from the compressor to the garage.

I used these assumptions:
120' of rigid pipe (your 110' figure plus vertical runs up/down the walls)
50' of flexible hose from the wall to your tools
Input pressures of 90 and 100 PSI
Heavy Duty Air Spray Gun from HF as a potential largest load @ 10 cfm

If you use 3/4" pipe with 1/2" hose on the end, your pressure drop will be approx. .5 psi.

If you use 1/2" pipe with 1/2" hose on the end, your pressure drop will be approx. 1.5 psi. FWIW, if you decide to run out to your backyard with 250' of 1/2" pipe, your pressure loss would still only be 2.5 psi.

If you use 1/2" pipe with 1/4" hose on the end, your pressure drop will be approx. 16 psi. (yes, that is sixteen pounds - if you had 100' or 1/4" hose the drop would be 32 PSI)

Moral of the story - stay away from that 1/4" coiled air hose.

Air Compressor Pressure Loss.jpg

[George Clark]

Lewis,

Just asking, what about a small lean-to behind the garage to house the compressor? Sure would simplify things.

George