Do two air compressors ever make sense?

[ckucia]

I may be looking at getting a new compressor. Budget is about $1000-1200. Looking at two-stage 220v single phase 80 gallon models. The Kobalt at Lowes and the IR at Tractor Supply both fit the bill for around $1000 (IR at TSC is on sale). I can get both of these locally without any shipping charges.

My 30 gallon oil less is about useless for anything but tire inflation. I'd like to be able to run air tools and eventually be able to paint vehicles.

Here's the 80 gallon model at Lowes: https://www.lowes.com/pd/Kobalt-80-Gallon-Electric-Vertical-Air-Compressor/1000528985

I can't help noticing that, for a few hundred more, I could get two 60 gallon compressors at Lowes with lesser specs but still two stage:
https://www.lowes.com/pd/Kobalt-60-Gallon-Electric-Vertical-Air-Compressor/1000542193

Is there any advantage to having two identical compressors - run one when you just need light air needs and both to do heavier work like sand blasting or painting. Maybe could rig up some sort of round-robin or progressive switch. Also will most likely always have one working if one needs repair.

Is this a crazy idea?

 

[930dreamer]

Two that's all? Three phase duplex compressors use an alternator to cycle between two pumps.

 

[unslow1]

I have two in both my garages but not the same. Each has a small one for little stuff. Then there is a large one in each that can run air tools and paint guns. It just keeps you from having to run the big ones when all you need to do is air up a couple of tires.

 

[byekryam]

What I did for one project I had was a 30 gallon air compressor, but it wouldn't run air ratchet guns for what I needed it for because of the capacity. I couldn't afford the right size compressor, so I went on Craig's List and bought a 80 gallon compressor with a busted motor and linked the two together for the extra capacity and it did the trick. Don't know if that's helpful or not in your situation, but it worked for me.

 

[vavet]

I have a somewhat similar situation at my work. I run the r&d test lab and use air cylinders for some of my testing. We have a huge air compressor for manufacturing, but they don’t run 24/7 like some of my test fixtures do. During the day, it’s nice to have the house air supply, but then I have to switch over to portable compressors to run over nights and weekends.
Our plant maintenance guys came up with a way to connect my portable compressors to the house air system using two check valves. This is important because we don’t want the house air to fill the compressors during the day and we don’t want my portable compressors to fill the house air system (with all of the leaks it has) during the night and weekends. Basically they both feed into a Y with a one way check valve. The output feeds my test fixtures. Because house air pressure is higher than the air compressor regulators, the portable compressors never run when house air is available.
You could do the same thing, second compressor would only kick on if your demand was so high that the first one couldn’t keep up.

 

[ckucia]

I have a somewhat similar situation at my work. I run the r&d test lab and use air cylinders for some of my testing. We have a huge air compressor for manufacturing, but they don’t run 24/7 like some of my test fixtures do. During the day, it’s nice to have the house air supply, but then I have to switch over to portable compressors to run over nights and weekends.
Our plant maintenance guys came up with a way to connect my portable compressors to the house air system using two check valves. This is important because we don’t want the house air to fill the compressors during the day and we don’t want my portable compressors to fill the house air system (with all of the leaks it has) during the night and weekends. Basically they both feed into a Y with a one way check valve. The output feeds my test fixtures. Because house air pressure is higher than the air compressor regulators, the portable compressors never run when house air is available.
You could do the same thing, second compressor would only kick on if your demand was so high that the first one couldn’t keep up.

Interesting. I had some similar thoughts with the check valves. It's also why, at least to me, two identical compressors made sense. If one of the check valves ever fails, you aren't potentially back feeding a small compressor from a large one. That would seem to have destructive "boom" potential - you'd need a safety valve on the low side to deal with that possibility.

I still think check valves and safety valves need to be in place with identical compressors, but you don't have that underlying imbalance to protect against.

Plus the two 60s would appear to outperform the 80 when both are running.

Another thing I thought of is I've read some of the manufacturers are overspinning the air pump to get better numbers at the cost of longevity. Seems there would be potential to replace the pulleys and slow the pumps down. Then the two 60s might be down to the same numbers as the 80 but would likely last a good while longer, especially when you figure in less run time for lighter duty.

For about $200 more, I don't see much of a downside, but it seems like someone else would have thought of it before if it was a good idea and I couldn't find much out there.

 

[u2slow]

I
Is there any advantage to having two identical compressors - run one when you just need light air needs and both to do heavier work like sand blasting or painting. Maybe could rig up some sort of round-robin or progressive switch. Also will most likely always have one working if one needs repair.

Is this a crazy idea?

Not at all. Very common arrangement on a ship.
- redundancy for equipment failure.
- staged pressure switches to run both for faster recovery. One is set to primary, one secondary. Usually reversed at set intervals (x days, week) to balance machinery hours.
- one type of spare parts to keep on hand.

 

[theoldwizard1]

My nephew was doing some sand blasting. The 2hp compressor he borrowed kept running out of air. I loaned him my 2hp compressor. He had space in the breaker box for another 240V load so we added another outlet. I happened to have had all of the necessary plumbing and hoses so he was in business. Never ran out of air again !


Yes, it makes sense when you are on a shoe string budget and are borrowing equipment.

 

[dagofast]

I have two compressors. Both are 20 gallon horizontal tanks on wheels. They each reside under different work benches. One is at the back of the shop and one is at the front. I usually run the one at the rear when I'm working up front and visa versa just so the noise, which isn't terrible, is farther away. I'll run both if I'm using air heavily, but that is rare. Mostly I like having a spare and portability. Although the rear unit runs off of 240V now. That makes it a little cheaper to run.

 

[NitroShark]

What you need to look at is CFM not tank volume. You could have several 60gal @10.7 CFM compressors and still have the pump continuously run after reaching set pressure.

The 2 models you picked:
10.7 60 gal
15.6 80 gal

 

[sberry]

Buy 1 decent 5 hp comp which is the benchmark for paint and body work.

 

[vanapplebomb]

I wouldn’t get the Kobalt (Campbell Hausfeld) compressors listed above because Campbell Hausfeld pumps have not impressed me as of late. That 80 gallon, for example, should be able to do better with 5hp on tap. A more efficient pump should be closer to 18 cfm @ 100psi, and 17 cfm @ 175 psi. Also, weighing in at just 410 LBs, you know it is a light duty unit.

 

[OccupantRJ]

I run two 5 hp compressors for cabinet blasting, but not at the same time. I alternate them to equalize wear and heat buildup. I also have a 6” thermostatically controlled sidewall fan to expell hot air out of the compressor room when the room temp reaches 90 degrees.

 

[RV8guy]

I have a duplex compressor at work. I have it set up that if demand is low only one pump comes on. If demand picks up the second pump kicks on.

 

[HenryAZ]

I just use one (Quincy QT-5), and have enough extra hose to reach about 150 feet outside the garage. The wife is using 100 feet of hose right now with nail and staple guns to finish off the inside of her new shed.

The main manifold had a 1/2" quick connect built in for when needing extra pressure for sand blasting.

 

[ckucia]

Just a follow up on the Kobalt compressors at Lowes. The pump on the 60 gallon and 80 gallon models has the same model number. Pulley size is different on the motor and presumably the 80gallon motor has a higher HP capacity.

 

[Mr_B]

go the 2 60 gallons, I done this for my home air, can run serious stuff on 2, economy on 1 or 1 into 2 tanks .
was a sale on the 60 gallons too which made it value option .
No safety issues, easy plumb/wire plus if one goes out you still got air .
Even my auto shop uses 2 compressors just 5hp units .

 

[finn]

Just a follow up on the Kobalt compressors at Lowes. The pump on the 60 gallon and 80 gallon models has the same model number. Pulley size is different on the motor and presumably the 80gallon motor has a higher HP capacity.

That’s pretty much how the industry works. My Champion pump is (was) available with different pulleys and 3, 5, and 7.5 hp motors to match.

Pretty sure Quincy and all the other old school compressor manufacturers do, or did, the same.

Price follows horsepower.

 

[sberry]

Buy 1 unit, simple, do the work. I circuit. I drain, I machine. There is no shortage of people done this,,, me included but it doesn't make it solid advice for a guy asking this type of question. Takes up 1 space on the floor.
My shate is elderly. I do have 2, second one I got for nothing and fix. Its a backup, its a storage and its a demand unit. I don't even have the breaker on till I might want it. I wouldn't start out buying 2, especially if buying new. This is about like a better wirre welder, buy 1 decent one first. They invented the 5 hp 2 stage for painting and sanding cars.
My master is a 3 hp 2 stage which is a bit small for sanding, with the tanks its good. But if I was starting over it would be a 5x80 which would do what I need it to do with 1.
As for economy, aint no cheaper to pump air with a second smaller unit, especially some pos. Get the leaks out, put a ball service valve, keep it pumped.

 

[sberry]

I run two 5 hp compressors for cabinet blasting, but not at the same time.

If I was doing this blasting would certainly run them both same time with a bigger jet. Blast is a chore the faster the better and if I was doing it much would be in a race to gear up any extra power I needed to get it done fast.

 

[sberry]

A hobby type, even serious car painter cant wear out a new brand compressor. Doesn't need backup.