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Compressor Aftercooler lessons-

DR Garage

New member
Joined
Jul 22, 2013
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2
So I finally got 240V to my garage, big deal for me w/ local electricians looking for close to $2K. Did it myself for around $500- Shhh. Researched compressors and settled on a Kobalt 3.7 HP, 60 Gal, 155 PSI. Would have liked to go larger but $$ were an issue. Got it in place and wired up and ran it for the first time. It ran up OK but the tank temps were really high and there was a ton of water (90% humidity, 90 deg day). I knew I needed to do something about that. Commercial aftercoolers were way too spendy so I looked to the net and then to my father in law’s old stock. He had some Slantfin heating tubing that looked just right for the project. I originally planned 2 parallel runs of 4’ but the stock was 6’ long. I carefully measured, cut and soldered in a nice piece with L grade copper, made supports etc. and then gave it a try. Well, I should have done more research. I originally used 50/ 50 solder and found out quickly that it could not stand the temps. I disassembled , cleaned and re-soldered with 95/5 which should have been OK. I’m not sure if it was the residue of the 50/50 or the absolute temps but the system failed 3x and I had to keep replacing joints.
Ultimately, I wound up with soft tube and all compression fittings between the pump and the fin pipe and that seems to work OK even though it is an ugly install ( did not have a proper bender). Cycled 4x and all seems well. Will add the water drain tomorrow and I should be good to go.
I was buying the last compression fittings at my local store today and explaining my issue to the clerk when a guy from a plumbing house chimed in and said- Oh yeah, you can’t run over 120 PSI on solder, you need to silver solder or braze, we do that all the time. Well, wish I’d known, I can silver or braze no problem if I know it is needed. Shame on me for not knowing but all seems well just now w/ the compression fittings and tank temp is cool as a cucumber w/ lots of water captured in the down leg.
Thought this might help someone down the road. D
 

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JJThrasher

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May 30, 2013
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Indiana
I have the same compressor. I bought a 10' roll of copper and twisted it into a coil between the pump and the tank. It still drops the water in the tank, but its cooler and keeps more water out of the lines.
 

jimgerken

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Nov 27, 2013
Messages
23
Wish I could find some of that slant fin tubing. My junk pile is not that well stocked.
 

jf781

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Aug 18, 2011
Messages
66
Location
IA
You don't want to have it go up from the compressor - you want it downhill incase any water/condensation goes *backward* after the pump has stopped. Water in the compressor head is not good.

Fix that and you've got a nice setup.
 

djd99

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May 4, 2009
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Location
Owosso,Michigan
You don't want to have it go up from the compressor - you want it downhill incase any water/condensation goes *backward* after the pump has stopped. Water in the compressor head is not good.

Fix that and you've got a nice setup.


Actully he can insert a check valve near the pump to remedy that problem.
 
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mayday0017

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Oct 20, 2010
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Houston Texas
Hmm... this is an all Noob thread almost, just FYI if you search Aftercooler you will find TONS of people on here who have built them (mostly using transmission coolers)
 

JamieK

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Aug 13, 2009
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Winston-Salem, NC
Maybe I'm not seeing it right, but it looks like there is only a few inches of pipe between the drain valve and the line back to the compressor. On a humid day, that may fill up quickly. You need some type of small reservoir down there to catch more water.
 

MrMark

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Jan 25, 2010
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Southern Cal.
Solder is rated for way more than what that guy told you. He was full of it. You just didn't solder it right. Look up the PSI of soldered joints in the copper handbook. You do not need to braze that at all.

95/5 is rated to 1090 PSI at 100 degrees working temp.

50/50 is only rated at 200 at 100 degrees.
 
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Boyd

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Dec 16, 2009
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866
Location
Forney, TX
Solder is rated for way more than what that guy told you. He was full of it. You just didn't solder it right. Look up the PSI of soldered joints in the copper handbook. You do not need to braze that at all.

95/5 is rated to 1090 PSI at 100 degrees working temp.

50/50 is only rated at 200 at 100 degrees.

Yep. I soldered my coiled discharge line last year and haven't had a single problem.

20130720_124056_HDR_zps4751737f.jpg
 

christopizza

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Dec 3, 2010
Messages
129
Location
NC
I was all ready to put up a pic of mine but it looks so bad compared to the others...

I was having moisture issues while painting a car so I just bought a coil of 5/8 copper tubing and tie wrapped it to a window fan. Spent no time engineering it - path is compressor to tank to copper tubing to water separator to air lines.

Finally started to get water out of the air lines - actually - a lot of water - really helps with the sand blasting cabinet, too.
 
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