When  I was doing autobody repairs on my 2000 Tundra, I realized that humid Florida summers were going to cause a problem with moisture in my air supply lines.  Borrowing inspiration from a random youtube video, I set out to build a dryer system using automotive A/C condensers and water traps (defunct air compressors).  My big compressor that I bought used off craigslist wasn't really 6 hp.  It was only 3 hp.  It didn't have the CFMs to run my automotive spray gun.  I still had my old 1.8 hp compressor, and I rigged them together to achieve the CFM required.

The way the system works, the very hot and very humid compressed air goes from the compressor straight to an A/C condenser that has an electric fan wired to run whenever the compressor motor is running.  The motor is 220V and the fan is 110V, so I took half of the switched 220V from the motor and a neutral and ground from a nearby outlet. Hey, it works!  The air condenses and all that moisture is turned into liquid and it runs down into the catch tank.  The dry air goes out the top of the catch tank and into the main air tank.  From there is goes into a manifold pipe that is angled downward, which would drain any moisture accumulated there.  It passes by another vertical pipe which is the final drain point before entering the moisture separator, then the moisture filter, the regulator, and final to the air hose connected to sander or spray gun.

The tee before the check valve connects to the unloader valve which relieves the air pressure from the check valve up to the cylinder head so that the compressor will restart next cycle.

During the summer, I sanded with a air sander for hours at a time and never got any moisture coming to the tool.  In fact, I really only needed to drain the catch tank regularly.  The main tank needed draining very infrequently and only a spit or two of water came out.  The other drain points were always dry.

I have since removed the smaller compressor from the system because I don't plan on ever devoting that much time and effort into an automotive project ever again.  Getting too old for that!  This system works very well.  Aside from dry compressed air (which Frosty mentioned in another post I was reading), it will prolong the life of your air tank by keeping water out of it to begin with.

Diagram is attached.

Compressors.pdf

I had to replace the compressor last year, but it's the same setup pretty much as the diagram, except I moved the check valve to after the catch tank.  I can't remember the reason, but this way the condenser and catch tank are depressurized in between cycles.

 

A simple air/water separator would not work? That was all we used when i was in Louisiana rebuilding transmissions.  

My thought exactly Billy, we put "line driers" on our compressed air lines right after the compressor tank and never got wet air. EXCEPT when some knothead ran a lot of air and didn't open the drain cock once in a while. 

My routine was drain the drier 1st thing in the morning and the compressor tank weekly unless the weather was humid and we were using a lot of compressed air. 

On the other hand I DO like to tinker around making things you can buy at a local store, that sort of goes with being a blacksmith.

Frosty The Lucky.

4 hours ago, Frosty said:

On the other hand I DO like to tinker around making things you can buy at a local store, that sort of goes with being a blacksmith.

I do need an "engineering outlet" to satisfy that part of my brain, and I also like a challenge.

Dx cooled compressed air dryers are definitely a thing for industrial systems.  Very nice job cobbling one together.  Not completely convinced regarding your electrical install, but if it works...