Currently a 15g DEWALT 5.0 cfm @ 90 in the deepest corner of the garage. I ran 3/8" threaded black pipe up a height of about 7', then out to the front, and back down to waist height where I built a little manifold (also 3/8" threaded black pipe) to provide one un-regulated (un-dried) output...then a regulator...then a desiccant dryer...then another output...then an oiler...and finally an (oiled) air tool output. It all works fine, but I was not getting the performance I expected from a 1/2"-drive Ingersoll Rand impact gun. And with a drill or a blowgun - forget it. And yes - I know that capacity plays a part; if I had a 30g or a 50g tank, I'm sure it would provide air longer...but when the pump finally activated it would need to run for 40 minutes! Anyway - I asked the pipefitter at work, and he suggested that I add an accumulator. He said I could either use a small tank, or just up-size my pipe, so I stepped up the diameter of 95% of my pipe run to 3/4". I guess it helped a little (it's certainly not worse!) but the pump still runs long & often.

So now I'm wondering...

Can I install a *second* machine of similar-but-not-necessarily-identical-performance and link both to my main piping with a TEE and a check valve of some sort? or *two* check valves? I don't want one machine to be "back-feeding" into the other. Rather, I hope & expect that they will work together - cycling on&off at infrequent & irregular intervals - to deliver the requested cfm(?)

Or would it be better to stick with just one machine...but up-size it to something with a bigger tank? Please note that I am just one retired person; I don't want and cannot afford a huge 10+cfm industrial behemoth.

Second (parallel) question:
I have a ball valve on my steel pipe (which of course is simply ON or OFF) and/but I wondered if there was such a thing as a diverter valve that operates in a similar manner as a ball valve(?) If I can't incorporate a TEE + a check valve (or two) perhaps when the pump activates on machine #1 I could simply switch over to machine #2 while machine #1 is recharging(?) in the same fashion as a motorcycle rider switches over to a reserve fuel tank when the main tank runs dry(?) Does such a thing exist?

Any suggestions will be gratefully received!