TheShrine
Well-known member
Is there any benefit to daisy chaining 2, 20 gallon 175 psi air compressors? If so...is there a right and a wrong way.
Thanks..DJ
Thanks..DJ
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Daisy chaining compressors
- Thread starter TheShrine
- Start date
sberry
Banned
Double the power might be considered a benefit.
No problem doing what you want. The way I do it is to have a place to plug each compressor outlet into a manifold and then take off from the manifold to the load. The manifold could be the piping system in the shop with a compressor plugged into each end of the system or anywhere that its convenient. Then you can choose to have one or the other pump on line or both if the workload requires it.
Someone will come along and tell you you have to go through the drill of having to run them both off the same pressure switch or some other wild *** scheme to synchronize their starting. They will be wrong.
What you gain with having two compressors online at once is more delivery to run tools that require large volumes of air to run them. One caution is to not have a relieving regulator between the manifold and either compressor.
lg
no neat sig line
Someone will come along and tell you you have to go through the drill of having to run them both off the same pressure switch or some other wild *** scheme to synchronize their starting. They will be wrong.
What you gain with having two compressors online at once is more delivery to run tools that require large volumes of air to run them. One caution is to not have a relieving regulator between the manifold and either compressor.
lg
no neat sig line
Delta74
Well-known member
cant see a problem with it, it wont increase your pressure, but should double your CFM, I would make it a point thou to add a shut off valve to each one thou in the event you have a failure in one of the units, at the same time you could adjust the pressure on settings of the two units, so on a low draw the one compressor would supply your needs, but on a larger draw both units would kick on and pump up the CFM for those air hungry tools.
all that said thou, consider selling both? buy one large unit that would match the output or even exceed the pair, and keep the plumbing simple.
all that said thou, consider selling both? buy one large unit that would match the output or even exceed the pair, and keep the plumbing simple.
Fast Orange
Well-known member
I've seen this done with larger compressors in a car dealers shop. If one compressor's pressure switch is set lower than the other,the one compressor can run constantly under a high use period while the other will cycle on and off. To avoid this problem,the units I saw used one pressure switch and an alternating pump controller. Not a cheap set up to duplicate...
LS6 Tommy
Well-known member
We use alternators on duplex units and staggered operator settings on separate units feeding the same manifold, so you have a "primary/secondary" setup. One runs for the majority of the time, the second (sometimes a little smaller) unit comes on if there's a failure of the primary or if the demand is high enough that the primary can't satisfy the demand.
Tommy
Tommy
79firebird
Well-known member
Yup will work fine. we have a 10 and 5 hp at work daisy chained. I use to do that with my 60 and 26 gal when i was blasting cars also had a 100 and 80 gal hooked up to it. just have one set to cut in at 90 and the outher one at 100 .
What kind of pumps are we talking about? There are a few ways to do it, you really don't want to just hook then together and go otherwise they will fight each other and their respective pressure switches. Personally unless you have some quality pumps I'd be inclined to sell both and put that money towards a good 60gal vertical unit.
Tommy gave you a good run down, what you are trying to do is called a duplex setup.
Tommy gave you a good run down, what you are trying to do is called a duplex setup.
Ross/Kzoo
Well-known member
We use alternators on duplex units and staggered operator settings on separate units feeding the same manifold, so you have a "primary/secondary" setup. One runs for the majority of the time, the second (sometimes a little smaller) unit comes on if there's a failure of the primary or if the demand is high enough that the primary can't satisfy the demand.
Tommy
Exactly. You also don't want both motors in their start windings at the very same time, too much current draw.
Jswain
Well-known member
At work we have two Quincy 80g compressors tied into a main air line, one of them kicks in when the pressure drops to ~110 and the second when the pressure drops to ~100 so only one of them runs when we aren't using a **** tonne of air, and they both run when we are. There is also another 80g tank tied into it, and a 30g tank closer to the controls...we use a lot of air haha.
justanengineer
Well-known member
What kind of pumps are we talking about? There are a few ways to do it, you really don't want to just hook then together and go otherwise they will fight each other and their respective pressure switches. Personally unless you have some quality pumps I'd be inclined to sell both and put that money towards a good 60gal vertical unit.
^^^Best answer yet IMHO.
Realistically, if your two 20 gallon compressors are each only 2-5 cfm its a waste of time, effort, and space. If your two compressors output at least 8+ cfm each then its probably worth it.
I have 2 60 gal Huskys, hooked together but made so either one or both will run and each one has a shutoff valve, so I can run only one if the need is only for a small amt of air and a 60 gal supply is fine. When sand blasting etc when large amts of air is required I run both. No problems with pressure switches working against each other and both are set at 120. Wired for all the amps they need. No problems after a couple of years use. Your mileage might vary.
I primed my car using a 33 gallon and 26 gallon compressor. Both were plumbed into a manifold, essentially a piece of pipe with inputs and an output. They were plugged into different circuits so as not to trip a breaker (one was 220, the other 110). One kicked on slightly before the other but it was not big deal. Both compressors ran and I had plenty of air.
A big compressor is always going to be better but in a pinch and for a one time thing, this worked fine for me.
A big compressor is always going to be better but in a pinch and for a one time thing, this worked fine for me.
Realistically, if your two 20 gallon compressors are each only 2-5 cfm its a waste of time, effort, and space. If your two compressors output at least 8+ cfm each then its probably worth it.
Whether this is a good idea or not has NOTHING to do with the output of the compressors and EVERYTHING To do with the needed output.
It is very easy to connect two...or ten air compressors in parallel. (You can't connect them in series) You can sync up the pressure switches in two ways.
1. Most compressor switches are adjustable. Even the ones from Harbor Freight. Pop it open and set them to the same pressure.
2. If one compressor is higher pressure than the other, simply set the pressure regulator to the same output pressure as the other one and connect them through the regulator. Now you can have one tank at 150psi and another at 120 and they will not fight each other.
I have an extra regulator I use just for this. It has a male quick connect fitting on both sides to easily connect two tanks with any air hose.
In my shop, I have four 120v compressors plumbed together. That's around 8hp output, more than one nice big one. They all run at a different pressure. I keep them in their own room so I can't hear them either...
Last edited:
sberry
Banned
The comps don't care what the switches are set at, for the most air set them to run at the same time. Only reason I have mine set different is I want one to run as the primary, my second is a relic, only used as needed.
justanengineer
Well-known member
Whether this is a good idea or not has NOTHING to do with the output of the compressors and EVERYTHING To do with the needed output.
It is very easy to connect two...or ten air compressors in parallel. (You can't connect them in series)
In my shop, I have four 120v compressors plumbed together. That's around 8hp output, more than one nice big one. They all run at a different pressure. I keep them in their own room so I can't hear them either...
Connecting them in series is very possible and easy to do, you just plumb lines between tanks, keeping a single output from one to the shop air manifold. If youre running multiple compressors you also dont necessarily need to adjust the pressure switches or regulators regardless of the plumbing, they wont "fight" each other, each cuts off when it reaches its individual limit. Personally, I would adjust them so that theyre setup as primary and secondary, but Im paranoid about PM and would want them to wear evenly.
Not arguing your point about sizing the compressors to the air requirements, but most of us on this board have similar requirements - ~8-10 cfm for general shop/light air tool use and 15+ for blasting and other heavy air uses. JME, but there is such a tiny difference in used price between the tiny "portable" compressors and decent smaller stationary industrial 8-10 cfm ones that the first just isnt worth the effort bc the second gives a much higher duty cycle and life span, half the noise, and saves room.
Well....thanks to all contributors. I have a one time project and will be using a table top blasting cabinet. A lot of good ideas here but my needs are temporary and I possess two 2 gal comps. Upgrading is always good but not now. I have 2 garages and each have a comp. My needs are for simplicity and temporary.
Any pics of a parallel set? I'll work through the pressure switch timing.
Any pics of a parallel set? I'll work through the pressure switch timing.
Ross/Kzoo
Well-known member
The comps don't care what the switches are set at, for the most air set them to run at the same time. Only reason I have mine set different is I want one to run as the primary, my second is a relic, only used as needed.
You're right about the compressors not caring. However if both compressors were 5 HP and 22 amps running, IF both compressors started simultaneously there would be approximately 220 amps of inrush (5 X 22 X 2 compressors). If there was a slight delay the amps would be 132 amps ( 110 amps inrush plus 22 running amps of the first compressor).
and I possess two 2 gal comps. Upgrading is always good but not now. .
Is there any benefit to daisy chaining 2, 20 gallon 175 psi air compressors? If so...is there a right and a wrong way.
Thanks..DJ
You have two different sets of information here, What do you really have?
lg
no neat sig line
Re: Daisy chaining compressorsq
My bad.....2 different 20 gallon comps. 1 single, 1dual. I think a manifold parallel set up w up/down pressure switch sequencing is the way to go but pics work for me. I'm in a wheelchair most of the time so I have to be creative. Not a lot of chances to get it wrong or redo.
You guys are "walking" me through the mistakes I would have made on my on. Me, my wheelchair/walker and 2 compressors will be a tight fit in my compressor room.
Thanks again!
You have two different sets of information here, What do you really have?
lg
no neat sig line
My bad.....2 different 20 gallon comps. 1 single, 1dual. I think a manifold parallel set up w up/down pressure switch sequencing is the way to go but pics work for me. I'm in a wheelchair most of the time so I have to be creative. Not a lot of chances to get it wrong or redo.
You guys are "walking" me through the mistakes I would have made on my on. Me, my wheelchair/walker and 2 compressors will be a tight fit in my compressor room.
Thanks again!
Re: Daisy chaining compressorsq
Ok clear up one more thing , you said in the first post that they are 175PSI compressors. Then you say one is a single. Are you talking single cylinder? Then that is not a 175psi compressor. What is the cutout pressure each compressor shuts off at?
As for a manifold it can be as simple as a pipe Tee with a line from each compressor plugged into it and a single line output. The Tee can be on the output of one compressor or remote with a flex line from each compressor plugged into it.
Like I said in my first post, don't worry about the pressure switches, Duck has it right.
lg
no neat sig line
My bad.....2 different 20 gallon comps. 1 single, 1dual. I think a manifold parallel set up w up/down pressure switch sequencing is the way to go but pics work for me. I'm in a wheelchair most of the time so I have to be creative. Not a lot of chances to get it wrong or redo.
You guys are "walking" me through the mistakes I would have made on my on. Me, my wheelchair/walker and 2 compressors will be a tight fit in my compressor room.
Thanks again!
Ok clear up one more thing , you said in the first post that they are 175PSI compressors. Then you say one is a single. Are you talking single cylinder? Then that is not a 175psi compressor. What is the cutout pressure each compressor shuts off at?
As for a manifold it can be as simple as a pipe Tee with a line from each compressor plugged into it and a single line output. The Tee can be on the output of one compressor or remote with a flex line from each compressor plugged into it.
Like I said in my first post, don't worry about the pressure switches, Duck has it right.
lg
no neat sig line
Last edited:
The one thing to be careful of here is that both compressor tanks are rated for the highest pressure.They will not fight each other.
170 cutoff= 150 psi in the line and one runs
Plus
120 cutoff= 100 psi in the line and both run.
Lower pressure unit CANNOT kick in when pressure is higher.
To those who said differently; convince me.
lg
This his how you plumb them in parallel. To plumb them in series would require you to modify the compressor and feed it air that is already compressed. (That's a 2 stage compressor)Connecting them in series is very possible and easy to do, you just plumb lines between tanks, keeping a single output from one to the shop air manifold.
The air pressure switch isn't the only part. Let's say for example you have a 120PSI compressor and a 150PSI compressor. You can't simply plumb them in parallel and call it good. When you put 150 PSI into the 120 PSI compressor, you will pop it's blow off valve, and most likely, the first tank isn't rated for as much pressure as the other one.If youre running multiple compressors you also dont necessarily need to adjust the pressure switches or regulators regardless of the plumbing, they wont "fight" each other, each cuts off when it reaches its individual limit.
In a situation like that you MUST plumb them through a regulator at the same pressure or it will not work.
My compressors are 120, 125, 135, and 150 PSI. They are all plumbed together and each tank stays at it's design pressure with the factory blow off valve.
This is about using what you have. Do you think I just woke up one day and said "I want four 120v compressors all stuck together!"? Just like the OP I decided it would make a whole lot more sense to plumb together what I have than to go buy another bigger compressor.JME, but there is such a tiny difference in used price between the tiny "portable" compressors and decent smaller stationary industrial 8-10 cfm ones that the first just isnt worth the effort bc the second gives a much higher duty cycle and life span, half the noise, and saves room.
We can argue all day about which system is better, but I wouldn't trade my four compressors for a single 8hp unit.
Last edited:
LS6 Tommy
Well-known member
Check valves on the storage cylinder output lines upstream of the manifold eliminate having to use multiple regs & changing relief valves (which is also NOT a good idea unless you swap the higher rated one out to the same rating as the lower one. NEVER increase the rating of the relief valve).
Tommy
Tommy
Check valves on the storage cylinder output lines upstream of the manifold eliminate having to use multiple regs & changing relief valves (which is also NOT a good idea unless you swap the higher rated one out to the same rating as the lower one. NEVER increase the rating of the relief valve).
Tommy
Let me ask a couple questions here, How do you know that the relief valve on a receiver tank is the proper one? If your receiver has no relief valve, how would select the proper one?
lg
no neat sig line
volleyball
Well-known member
This is the way to do it. You should already have a check valve before the tank but you'll need another on the output of each.Check valves on the storage cylinder output lines upstream of the manifold eliminate having to use multiple regs & changing relief valves (which is also NOT a good idea unless you swap the higher rated one out to the same rating as the lower one. NEVER increase the rating of the relief valve).
Tommy
Another thing is if time is not important, for a 1 time use, borrow all the tanks you can and just not plug them in. Just manifold them together. You'll have air for a lot longer. you could plug 1 in if your pressure got really low just to lessen the recovery.
Let me ask a couple questions here, How do you know that the relief valve on a receiver tank is the proper one? If your receiver has no relief valve, how would select the proper one?
The max working pressure should be stamped into the tank somewhere. If it's not you probably don't want to use that tank. Your blow off valve should be about that pressure or less.
I suppose you could use check valves to do the same thing, but your air compressor probably has a regulator mounted to it already...use that.
Dren
New member
Well....thanks to all contributors. I have a one time project and will be using a table top blasting cabinet. A lot of good ideas here but my needs are temporary and I possess two 2 gal comps. Upgrading is always good but not now. I have 2 garages and each have a comp. My needs are for simplicity and temporary.
Any pics of a parallel set? I'll work through the pressure switch timing.
If everyone considered the "one time project" comment this would all be much more simple (granted this comment wasn't until a later reply). Two compressors connected to a simple manifold. Set both compressors at, or below, the lower of the two compressors max psi rating. Permanent installations, multiple switches, etc, etc all become pointless if this is for a one time project.
I'm in a similar boat, with a one time project. I don't currently have the money or space for a larger compressor so I'll be going this route. After this project is complete I shouldn't need the extra cfm capacity until I have my shop/funds in better order.
Last edited:
Dren
New member
@ jeremy v
Nice and simple, I like that manifold.
Nice and simple, I like that manifold.
volleyball
Well-known member
add a shutoff valve and problem solved. HF sells a 3 headed coupler. It is round but functionally the same.
I may have missed it told somewhere, but I am assuming these are both 120v compressors.
If you want something quick and simple just make a manifold like the one in my picture, except make it with 2 male quick release fittings instead of just 1. Use short hoses and plug the outputs of your 2 compressors into both of the male fittings. Run your tool hose out of one of the female quick releases and you should be good to go. Set both your compressor output regulators at roughly the same pressure (the ideal pressure for the operation you want to perform). Changing the cut-in and cut out pressures of the compressors will most likely achieve nothing for a short term setup like this, because the likelihood of them both kicking in and out at the exact same instant is pretty slim. Just make sure to plug them into different garage circuits and it shouldn't matter. If you are really nervous, plug them into circuits that are on opposite phases from each other at the panel which would then ensure no tripping of the main, because the inrush currents would not add to each other even if both start at exactly the same time.
Tank size, regulator settings, pressure valves, etc.......This is what I'm look'n for.
Thanks for everyone's submissions. I learned a lot.
I may have missed it told somewhere, but I am assuming these are both 120v compressors.
Just make sure to plug them into different garage circuits and it shouldn't matter.
If you are really nervous, plug them into circuits that are on opposite phases from each other at the panel which would then ensure no tripping of the main, because the inrush currents would not add to each other even if both start at exactly the same time.
Now that is good thinking.
Apart from makers dishonest cfm figures I've watched with a clamp meter most single phase compressors go into amp overload well before the pressure switch trips.
When you've got the shop lights flickering with the pulsing overload at high pressures you've gone too high.