Combining two air compressors

[jomobco]

Weird question but I have a problem. My current compressor is a Home Depot husky with specs: 60 gal, Delivers 11.5 SCFM at 40 psi and 10.2 SCFM at 90 psi
135 PSI maximum pressure

It's not big enough. Can I just buy a second of the same compressor and combine the two with a pipe running between the plug on the side of the compressor? This would give me twice the CFM and 120 gallons of tank. Has anyone done this? Why wouldn't it work? I'm thinking because the pipe running between the two would be the weak link?

 

[alecmcmahon]

While I cannot comment on if this would work or not.

Would it not make sense to sell your current compressor and buying a better one rather then buying a second of the same compressor that is undersized for you and trying to frankenstien them together?

 

[jomobco]

It would make sense but may not necessarily be the best value if this would work. For ease of discussion the next bigger home depot husky is:
Powerful 5 HP engine provides up to 10,000 hours of extended life
175 psi maximum pressure
Delivers 12.6 SCFM at 90 PSI to provide quiet, abundant airflow to power multiple tools
Steel 80-gallon tan for $1079. Less the $200 I might get for my current unit. That increased PSI would certainly make the 80 gallon tank last a lot longer than the 60 I would imagine.

My current set-up is $439. X 2 it has better specs with the exception of overall PSI.

 

[CUSTOMMANCAVES.COM]

You will not double your SCFM or PSI by combining tanks. You will only double your air supply.

 

[isaac338]

You will not double your SCFM or PSI by combining tanks. You will only double your air supply.

If you have two pumps, your total CFM output will be the sum of both their outputs.

 

[Nosferatu]

You will not double your SCFM or PSI by combining tanks. You will only double your air supply.

And you'll double the amount of power you use to do it.

 

[Chestrockwell]

I am in the process of doing this. I have 2 80 gal comps each has a valve at outlet, then rubber hose to a T, then off to the dryer, then off to the shop.

Not sure why OP says the pipe between would be the weak link. This shouldn't be an issue if done properly with some flexible lines.

The part I put most thought into is the wiring. First thought they should come one separately and off together but then you would have 1 compressor filling 160 gal. most of the time. So my plan is to wire them together on the same pressure switch (with proper contactors to handle the full current for each motor). Still looking for practical ideas on this part of the setup, though.

Of course 1 bigger compressor would be more efficient and simpler but when you get 2 nice units for cheap it is hard to justify the $$$ on a 10HP unit.

 

[Chestrockwell]

Oh and don't forget the extra $$ for extra wiring, conduit, breakers, piping, fittings, hoses, clamps etc. add a big amount to this project.

 

[CARS]

The part I put most thought into is the wiring. First thought they should come one separately and off together but then you would have 1 compressor filling 160 gal. most of the time. So my plan is to wire them together on the same pressure switch (with proper contactors to handle the full current for each motor). Still looking for practical ideas on this part of the setup, though.

Each tank inlet has a one-way valve. Air goes out, not back in. One could easily be added to a tank outlet I would think. Might be a restriction though.

Most body shops have 2 compressors (well, the big ones have a large rotary screw compressor). I have talked to compressor salesmen and they state that it is often recommended to run 2 smaller compressors v/s a one large one. The starting load of 2- 5 hp compressors, with a staged start (2 different start psi switches) is FAR less than starting a 10 hp compressor.

(i.e.... the lights wont dim every time it turns on)

 

[jomobco]

I guess if I'm running hard lines in the shop I could just t the hard line and run both compressors into the supply. Both are 110v so wiring isn't an issue. I think it would be best to have them on separate breakers in case they both kick on at the same time. Good points about shut off. My biggest issues are when I plasma and I think the double supply of air might get me close. Heck I could add a 3rd compressor for slightly more than the next bigger one at HD. The noise would **** though. I wonder how much louder it would be than a comparable single unit?

 

[Chestrockwell]

There is a 100A breaker feeding my compressor shack and I can turn both compressors on at once and the lights don't dim, there is no problem with that.

Other reason I am starting and stopping the motors on the same switch is because with 2 separately switched motors it would be tough to stop them at the same time. So one compressor runs for a long time to reach it's off pressure. It's kind of stupid because when I have the plasma table running for 45 minits straight and I'm running a die grinder or whatever else at the same time; that higher 'off pressure' compressor runs all the time.

Even 2 120V compressors don't seem like enough for plasma cutting if you ever get into gouging or long cuts you will probably never be happy with them. I would strongly suggest getting a 240V unit and proper sized wire/breaker.

 

[Vicegrip]

I run staggered cycle systems at work all the time. Set one compressor to come on at a slightly higher pressure than the other. This means one will start to make up air and will be the only one to come on if you only draw a little bit off. The other one kicks in when the first cannot maintain the second starting pressure point. Every so often switch the pressure settings so the other compressor comes on first. You can also just leave it set so the same compressor always runs first. In the home setting you don't need to worry much about cycling them both equally. Do not run both on one switch as most pressure start switches also have a cylinder unloader built in.

No fancy wiring, no high load from two motors coming on together, less noise. Simple plumbing, a T fitting. There is nothing wrong with a long run time for a compressor. In fact, like cars, it is good for it as it heats the oil and gets moisture out.

 

[keweenawbee]

I used two together with a T arrangement for my air hydraulic log splitter. Made a ton of racket but got the job done. Finally bought a 60 gallon vertical oil lubricated and the noise difference is like night and day.

 

[ChristopherLutz]

Weird question but I have a problem. My current compressor is a Home Depot husky with specs: 60 gal, Delivers 11.5 SCFM at 40 psi and 10.2 SCFM at 90 psi
135 PSI maximum pressure

There is no reason this can't (or even shouldn't) be done. In another forum there is a whole thread on this.....I just can't seem to find at the moment.

Is your problem working time or max PSI?

As one poster said above, your PSI will not increase at all in this set up....the motors aren't strong enough to compress the air any more than 135 PSI; however, you will effectively double the working time you have at whichever setting you're working with.

Your spec above looks like an oiless version - 2 of these would be LOUD.

 

[scooterseats]

Industrial settings frequently use multiple compressors for factory air supply. They are always setup with a "Lead" unit and "Slave" units. The "Lead" unit is set to come on first and typically carries all the load until the load exceeds the capacity of the "Lead" compressor then the "Slave" compressors come on to help out. If you are concerned about one compressor running more than the other then just routinely alternate the "Lead" compressor with the "Slave" units to balance out the run time of the individual units. I would set the units to come on in 5# differences with the same delta P the units will also cascade with this same 5# drop on shut off pressures.

 

[uhohjim]

If you have two pumps, your total CFM output will be the sum of both their outputs.

EXACTLY...+less down time between Start ups on the compressors.........

 

[TAMPAGT07]

Best advice...Sell it and upgrade....

 

[nehog]

I have my shop compressor, and a portable IR compressor. The shop one is about 8 to 10 CFM which is not enough for a few things I do. The IR portable is 4.5, which combined with the shop gives me just enough air.

I made up a short hose with two male connectors, and a ball valve in the middle. Close the valve, connect the two compressors (with the valve closed there is no leakage) then open the valve. Takes about 30 seconds to do. I use this configuration about once a year (maybe twice, not not often...)

 

[jam0o0]

if you're planning on running 2 oil-less compressors i sure feel bad for you neighbors. i can't work around those things. they are just soooo much louder than low rpm oil-bath unit.

the only benefit to getting a second cheapy compressor is that replacement cost when they die is a smaller bite. but you'll be replacing them more than twice as often.

if you figure in the cost of an enclosure to cut down on noise then i bet the better compressor is a better deal.

 

[toolsd]

There's a few more issues that haven't been addressed.

To make a long story short, I see no problem with adding another compressor. However, you'd be wise in this setup to switch between the two units separately (some sort of two way valve could be easily arranged to switch one out, and the other in).

Without some sort of rather complicated schemes, you could wind up having only one unit pressurize all 120 gallons. The problem there is that units in this quality range usually DO NOT have a hundred percent duty cycle. That's what limits them to whatever size tank they are on, can't fill up a lot more than that without a lot of undue stress on the thing.

If you are using single stage units rated for 100 percent duty cycle, just go for it. Staggering the pressures a bit will be fine.

With two units, and a simple valve arrangement, you can switch between the two, and keep your volume and pressure up, AND reduce the duty cycle time on both units. A win win, and is nice that you don't have to sell a unit at some reduced price to upgrade.

I've found that in ANY high use air situation, sitting at the sand blaster, running my die grinder (it's a hog...), taking a break as often as you'll need to anyway to switch between the units supplying your shop piping wouldn't be a problem at all.

By the way, running a compressor to the point everything warms up is bad in a way. The warm air (inevitable because of compression, boyles law) eventually warms up the tank. THEN, all the moisture in the air, stays in the air and winds up in your tools, sandblaster or paint. When it first starts up and everything is cold, the moisture condenses inside the tank (not great for the tank, but it keeps it out of everything else) and you get nice dry air at the point of usage.

Keep in mind that the water separators common to most systems are really water PARTICLE separators. Water VAPOR separators use either a dessicant or a heat exchanger (usually CRAZY expensive using refrigeration).

Lastly, and I'm sure this has been hashed and hashed and hashed here at some point, is that in deriving what you really have for horsepower on top of these things, you need to figure out the 110v amperage, and divide by 15 (as a very rough rule of thumb). A 15 amp motor (running on 110v) is 1 hp. Many air compressors will list this thing as a 5hp or whatever... it's nonsense. You're not gonna get but about 4 or 5 cfm at around 90psi out of 1 hp. It's all fairly linear in the ranges we play with these things.

All generalities, but will serve better than relying on whomever's advertising department figures.

Tools

 

[drmoonshine]

It would work however you would just have more compressed air. I don't think it has the intended effect.

 

[Chris Adams]

If you have two pumps, your total CFM output will be the sum of both their outputs.

Not exactly. Plumbing has more effect on CFM output at the job than the compressors.
Or in plain language, it ain't gonna work like a person might think.


I think the problem is at the use end, not the pump end.


Adding after seeing some newer posts;
The problem that comes to mind is duty cycle, build design.
If you are eating that much air, you are going to be running one compressor a lot, or two compressors a lot. However you are looking at low duty cycle compressors.
A single industrial 80 gallon can be bought used for a few bucks more than you could sell your single homeowner grade 60 gallon. Or even less...
We just put a 4 cylinder 80 gallon in a buddies garage, sold his Husky '7' horsepower 60 gallon Home Depot machine and after replacing all the brass and electrical on the 80, were still over a hundred ahead.
Big compressors sell fairly cheap, as they are a big pain to move or feed electricity to.

 

[Vicegrip]

Not exactly. Plumbing has more effect on CFM output at the job than the compressors.
Or in plain language, it ain't gonna work like a person might think.


I think the problem is at the use end, not the pump end.


Adding after seeing some newer posts;
The problem that comes to mind is duty cycle, build design.
If you are eating that much air, you are going to be running one compressor a lot, or two compressors a lot. However you are looking at low duty cycle compressors.
A single industrial 80 gallon can be bought used for a few bucks more than you could sell your single homeowner grade 60 gallon. Or even less...
We just put a 4 cylinder 80 gallon in a buddies garage, sold his Husky '7' horsepower 60 gallon Home Depot machine and after replacing all the brass and electrical on the 80, were still over a hundred ahead.
Big compressors sell fairly cheap, as they are a big pain to move or feed electricity to.

I am having a hard time following your statements regarding consumption. A draw is a draw. If it exceeds the compressors CFM rating at the pressure it is being drawn at the pressure in the storage tank will drop. A standard format 4 cyl compressor is two 2 stage compressors that share a crankshaft, tank and controls. Two 2 stage compressors side by side will combine the total output at or nearly 100% the cap of the two by themselves. Flow rate at a given PSI is related to plumbing.

 

[6768rogues]

Yes, it can be done and I have done it for a large job. Identical compressors make it easy with no concerns whether one compressor can provide pressure that the other tank is not able to withstand. I would adjust one pressure switch a little so they are on a lead-lag cycle rather than coming on at the same time.

 

[Chris Adams]

I am having a hard time following your statements regarding consumption. A draw is a draw. If it exceeds the compressors CFM rating at the pressure it is being drawn at the pressure in the storage tank will drop. A standard format 4 cyl compressor is two 2 stage compressors that share a crankshaft, tank and controls. Two 2 stage compressors side by side will combine the total output at or nearly 100% the cap of the two by themselves. Flow rate at a given PSI is related to plumbing.

I was replying to the (quoted) post suggesting that flow rate would double with two compressors.

Never going to work that way, even if you had two big pipes into one. If for no other reason than system loss or turbulence.



I think you thought I was replying to the main thread.
Which I did in the lower part of my post, referring to duty cycles.

If you are gobbling that much air that a HD compressor and 120 gallons of air can't keep up with, unless you add another cheap HD compressor, then you are going to be running those low duty cycle compressors way, way past their intended abilities.

The OP is saying he needs a LOT of air thus is over using his small compressor, where it can't even keep up.
A bigger (or axillary) tank would handle that, except he says it won't because he needs it a LONG time.

So he needs lots of air for a long time.

Two low duty cycle compressors may produce more air, but if he is actually using that much flow, he needs something designed for it, not a much less efficient frankenpressor setup.

The stated goal was to save money by not buying an adequate compressor.
For the cost of two inadequate compressors, cobbled together, wired and plumbed, he could easily get an adequate compressor, selling his present inadequate compressor.

I am saying the savings are not real, just illusionary.

Like buying a Hybrid car, you will NEVER get the cost difference back.

 

[larry_g]

Not exactly. Plumbing has more effect on CFM output at the job than the compressors.
Or in plain language, it ain't gonna work like a person might think.


I think the problem is at the use end, not the pump end.


.

I'm so glad to learn this. Boys we only need a 1/2 hp compressor and put a really big end on the pipe...

Chris
Some of what you have said in your posts here is leaning toward reality, some is really close to fantasy. You really need to do some research on this subject.


To the OP, Nehog has about the simplist correct answer. If you keep plugging small compressors into the piping system you will continue to get more air volume. If you burn out the compressors you will understand why so many warnings of duty cycle. What tool are you trying to run that is taxing your system? Do you have a piping system or just a hose from the compressor? What size hose and fittings are you using?

I have in my younger years had 3 compressors all connected to the system for some high use jobs. Neat thing is that 2 portables are quick attach and quick to move out of the shop to some remote job. You have no worry if your compressors are not matched. They only care what their pressure switch tells them to do. You only really have to worry if your electrical is able to handle the load. I always set the large compressor to come on first and if it doesn't keep up then the second and third kick in.. Tank size is also perty much out of the picture. Once the compressor kicks in the tank is out of the picture.

Think of the tank like the battery in your car. It only needs to start the engine, once started the alternator drives the electrical load. If you upgrade to a meggawatt music system you will soon find that your battery goes dead driving down the road. The idiot will go get a big battery and finds out he can only drive a bit longer till the battery goes dead. The informed get a bigger alternator to carry the increased load. Think of the alternator as your pump(s) and the tank size as your battery.

lg
no neat sig line

 

[Chris Adams]

I'm so glad to learn this. Boys we only need a 1/2 hp compressor and put a really big end on the pipe...

Chris
Some of what you have said in your posts here is leaning toward reality, some is really close to fantasy. You really need to do some research on this subject.


To the OP, Nehog has about the simplist correct answer. If you keep plugging small compressors into the piping system you will continue to get more air volume. If you burn out the compressors you will understand why so many warnings of duty cycle. What tool are you trying to run that is taxing your system? Do you have a piping system or just a hose from the compressor? What size hose and fittings are you using?

I have in my younger years had 3 compressors all connected to the system for some high use jobs. Neat thing is that 2 portables are quick attach and quick to move out of the shop to some remote job. You have no worry if your compressors are not matched. They only care what their pressure switch tells them to do. You only really have to worry if your electrical is able to handle the load. I always set the large compressor to come on first and if it doesn't keep up then the second and third kick in.. Tank size is also perty much out of the picture. Once the compressor kicks in the tank is out of the picture.

Think of the tank like the battery in your car. It only needs to start the engine, once started the alternator drives the electrical load. If you upgrade to a meggawatt music system you will soon find that your battery goes dead driving down the road. The idiot will go get a big battery and finds out he can only drive a bit longer till the battery goes dead. The informed get a bigger alternator to carry the increased load. Think of the alternator as your pump(s) and the tank size as your battery.

lg
no neat sig line

You understand that I've built, from scratch, a half dozen compressor systems?
Posted my first Frankenpressor, under that heading some years ago.

You don't seem to understand what I am saying, so you assume I don't understand how they work.
Um, yes, I do.

You are kind of missing what the OP said, and what I was replying to.

He, not I, said he needed more air volume than his ? horsepower compressor can sustain.
He, not I, said that he needed more volume than two 60 gallon tanks could supply.

Now I have no clue what he's doing that a common, say 5 horsepower, compressor with 120 gallons of reserve can't handle, as we have run a paint booth with two guns running with less, but heck, who knows what he is doing.
It doesn't matter, if that's what he wants.

Duty cycles are what I was discussing. You are familiar with those, right?
If he is indeed, gobbling 10.4 plus cubic feet of air, over enough time that 120 gallons of reserve can't allow his ? horsepower compressor to keep up, then he needs something that will supply 10.4 plus cubic feet of air 'indefinitely' .
This is not my opinion, it's the posted desire.
And the cheap compressors, (he specified the price) are not designed to do that, even in tandem, at least, for a decent interval of time.
Despite which, the question was about economics, not hardware, or how to do it.
It was a feasibility question.
i.e. Is this a good idea? Invest one compressor (already owned) add another compressor (to be purchased) plus wiring, plumbing, design (to be purchased) to attain a goal more economically solved for less money by buying a purpose built unit, and recovering some investment from the other already owned unit.

Or is that all way too 'fantasy'?

 

[TLCDino]

Dude, my thinking is bite the bullet and upgrade. The additional complexity and hassle don't seem worth it. The units at HD are great, but they are limited. If you are gobbling that much air, in the long run the proper tool will do the job more economically over time.

Just my two cents.... You asked for opinions....

 

[1redTA]

a shop I worked at had three 3phase 2stage 4 cylinder air compressors, the main would run alot with the second kicking in regularly. They upgraded to a rotary screw and the one three phase left over sat there on vacation. The rotary screw would cycle even whil two people were arc gouging and a helper used an air want to clean the floor

 

[jomobco]

Thanks for all the input. A few points of clarity:
I'm not looking to save money, I'm looking for the best way to spend my money. I'm not one to cut corners however I'm not one to spend money just to spend money.

The HD unit I refer to is this:http://www.homedepot.com/Tools-Hard...splay?langId=-1&storeId=10051&catalogId=10053

An oil not diaphragm compressor and I believe a 100% duty cycle. In reading the PDF manual it says to run the compressor for 30 minutes upon initial purchase to break it in which would lead me to *** U ME it's 100% duty cycle or at least 30 minutes which should be plenty. If I could work for twice as long as I can now on a tank (which I would achieve from what was said having twice the volume and fill capacity of air) I might be close to being happy. It's not a PSI issue I'm lacking. Adding a few feet of piping and a t to tie two hard lines together to me doesn't seem excessive and in fact seems like the best value for the situation I have right now. And given the price of less than $500 to double what I have now it I think it makes the most sense. Thanks for the input everyone!

 

[cnc-me]

They make and sell duplex compressor units all the time, so no problem
combining two units together.
Use a common pressure switch, with a timer set to about 10 seconds to one of the mag. starters. That way both motors will not start at the same time.
I have wired units like this before.

 

[Chris Adams]

Thanks for all the input. A few points of clarity:
I'm not looking to save money, I'm looking for the best way to spend my money. I'm not one to cut corners however I'm not one to spend money just to spend money.

The HD unit I refer to is this:http://www.homedepot.com/Tools-Hard...splay?langId=-1&storeId=10051&catalogId=10053

An oil not diaphragm compressor and I believe a 100% duty cycle. In reading the PDF manual it says to run the compressor for 30 minutes upon initial purchase to break it in which would lead me to *** U ME it's 100% duty cycle or at least 30 minutes which should be plenty. If I could work for twice as long as I can now on a tank (which I would achieve from what was said having twice the volume and fill capacity of air) I might be close to being happy. It's not a PSI issue I'm lacking. Adding a few feet of piping and a t to tie two hard lines together to me doesn't seem excessive and in fact seems like the best value for the situation I have right now. And given the price of less than $500 to double what I have now it I think it makes the most sense. Thanks for the input everyone!

Just pulled one of those out of a shop to replace with the V4 I mentioned earlier. It was labeled as 7 hp, but that's because it was sold before the law change.



The duty cycle on that is not 100%.
My buddy changed it out when he put in a sand blaster cabinet.
It started to overheat and smell 'funny' the first day he put in the cabinet.

He bought it used, almost new, for 200. Sold it for 225, so it was a win.
You might look at their V configured one that is virtually the same, also made by CH.

I have one of those, it runs cooler, and less noise than that one. About the same price, plus or minus a few bucks.

They do have a D-switch problem, read the reviews. I had to change mine. They get 29 bucks for the factory D-switch, not a warranty part when the red knob pops out.
You can get the parts straight from CH, where they don't get confused about which switch is on it, like 'Husky'.

 

[poprockcrusher]

run 3 at the shop ..they all run at the same time 160 psi

 

[socapots]

I guess if I'm running hard lines in the shop I could just t the hard line and run both compressors into the supply. Both are 110v so wiring isn't an issue. I think it would be best to have them on separate breakers in case they both kick on at the same time. Good points about shut off. My biggest issues are when I plasma and I think the double supply of air might get me close. Heck I could add a 3rd compressor for slightly more than the next bigger one at HD. The noise would **** though. I wonder how much louder it would be than a comparable single unit?

if that your main concern. You could probably get away with just putting another tank. Once its up to pressure you will have lots of "Reserve air" to do your cutting.. NO? I hope yes. This is something i am going to need to do with my system for my plasma cutter.. I only got a little 20Gal tank.
I Know a friend of mine runs that kinda setup for his shop(One man mechanic shop) and i am pretty sure the little compresser he uses to pump has been the same one for at least 8 years. And it sees daily use.

 

[Falcon67]

An oil not diaphragm compressor and I believe a 100% duty cycle. In reading the PDF manual it says to run the compressor for 30 minutes upon initial purchase to break it in which would lead me to *** U ME it's 100% duty cycle or at least 30 minutes which should be plenty.

I have a Campbell Hausfeld model of the same compressor. When I looked at these, the CH, Husky, Sears, etc were the same basic units with different colors and prices from $399 to $599. I bought the CH for $399. At that moment, blue paint was apparently cheaper than red or black. The manual does not list any duty cycle at all. The pump on those units is listed "good' for up to 3000 hours.
http://www.chpower.com/webapp/wcs/stores/servlet/chPrd3_10051_10001_92505_-1_10646_10693_

Use a common pressure switch, with a timer set to about 10 seconds to one of the mag. starters. That way both motors will not start at the same time.
I have wired units like this before.

Personally, that's what I'd look to do. Otherwise you'd want one way valves on the output of both compressors before the T. Otherwise, first guy on tries to supply air demand and try to fill the other tank.

Also, don't forget than HF sells a compressed air conditioner for under $400 that gets decent reviews.
http://www.harborfreight.com/compressed-air-dryer-40211.html

 

[GlenC]

This is the issue I am dealing with for a second shop. My main compressor is a Atlas Copco 5hp Direct drive LT with a 80 gallon tank. It does almost all I need... only occasionally using some of my larger Dotco sanders does it drop below 90PSI... At the other garage, I only have a 3HP Craftsman ... not enough! Now, I like the idea of having one small and one larger... maybe 6 cfm and 15 cfm set at staggered on pressures and same cutoff, I can use both when the volume is needed or just use one or the other as the job dictates. I think, depending on cost that two or three compressors the same size would be great.

Multiple compressors is not any different from a two cylinder single stage compressor, you would just have a 4-cylinder single stage compressor, double the volume (CFM) and same pressure.

Glen

 

[kenfain]

Wow! Some of you guys are putting way too much thought into this. The point, if I'm understanding, is to beef up the cfm for a plasma. So only turn it on, when using the cutter. Leave it pressurized, switch off until needed. No filling 120 gallons, no 100% duty cycles. It's not even there till you need it. They don't even have to be in the same garage. Only on the same plumbing system. I have a compressor on either end of my shop, not by choice, just worked out, space wise. I only use one, but the other works as a extra receiver tank, or even extra compressor, if needed. I believe I've seen threads around here, that claim great success doing exactly what the op is suggesting. As to the noise, yep, there's that.

 

[GlenC]

Wow! Some of you guys are putting way too much thought into this. The point, if I'm understanding, is to beef up the cfm for a plasma. So only turn it on, when using the cutter. Leave it pressurized, switch off until needed. No filling 120 gallons, no 100% duty cycles. It's not even there till you need it. They don't even have to be in the same garage. Only on the same plumbing system. I have a compressor on either end of my shop, not by choice, just worked out, space wise. I only use one, but the other works as a extra receiver tank, or even extra compressor, if needed. I believe I've seen threads around here, that claim great success doing exactly what the op is suggesting. As to the noise, yep, there's that.

I agree!

 

[jomobco]

I went big instead of duo
http://www.garagejournal.com/forum/album.php?albumid=3306

 

[e30bradley]

Nice compressor^!

I have a similar situation.. I am currently running one 220v ~25 gallon compressor. It builds up to about 160 PSI and makes 6.3 CFM @ 90 psi. Another one of these units is available for a good price. If I where to run both of these together would I simply connect the output of both units together and run my hose off that? Or once I plumb the garage run both into the plumed system? I am looking for more CFM and capacity. The current setup isn't adequate for any die grinders or air sanders let alone the media blaster or plasma cutter I may have someday.

IF I had two compressors I would need 2 independent circuits right? At that point it seems like its better to just get a bigger unit due to the added wiring cost.