Air Compressor aftercooler Info thread

Well the plumbing of your air lines looks very nic!

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I have to say that I am a believer in @DnKFab’s frigerated air dryer.

Here is my not as inexpensive as his but patterned off his idea. I’ve got $175 in this setup with an $85 fridge, $60 in 40’ of 1/2" copper tubing, and the rest in fittings, and the two house water filter housings for the desiccant.

Compared to no cooler water collection at my plasma, initial trials with the fridge and final setup, wow.

I would get 2 tablespoons of water at my plasma water sep (about half as much in the water sep mounted on the air tank) after about 1 hour of actual cut time, then near zero with the initial setup, unless I did a stupid and used the same airline as a blow gun feed, now I have a drip leg after the fridge and before the desiccant traps. Initial blow out of lines put some water in the first desiccant and before I put the drip leg in trap, nothing since.


Thanks @Sticks
I like ur lines going thru the sides better. I was nervous about hitting a refrigerant line.

All your cooling lines run up the back of all refrigerators and into the freezer portion only on small units like ours. Non freezer units will have a coil in it somewhere in the ceiling or back wall.

Besides, at $35 for yours …what’s to loose?


$35 dollars!!! Lol. I never open mine anymore with the extol filming the video to show you guys. But it would have been nice to do it like yours.

I like the idea of diy they are both pretty neat. Then they work is great. I do wonder how well they stay cool if you was to do a couple hours of solid cutting or long pulls blasting.

Before I bought my air dryer I was thinking a small deep freezer full of ice.

One could freeze the water bottles before putting in the refrigerator if you were anticipating a long day of cutting (assuming that this cooler is what is making the difference in water removal from the air).


The cold drops the moisture out of the air. The reason I asked about these fridges I have a new one at work that can barely get my drinks cold in 4 or 5 hours. I wonder if they can keep up.

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A bar fridge of dorm fridge is about 100btus-250btus and uses 75% of the energy just is combat the fridge’s energy gain from the outside world so about 25% of those are use to extract energy from the product inside. A harbour freight air dryer is about 650 btus but uses 90+% of its energy to extract heat from the product (the air)

So the bar fridge will do about 25-62.5btus of work and the harbour freight air dryer will do about 585 btus. the harbour freight air dryer does about 10x the work.

(I am making some large approximatations and estimations on this)

I also would be curious how a long session would work.

They would work as a heat sink but may have the added effect of tripping the fridge into not running it’s compressor until the internal temperature of the fridge a has warmed after the ice has absorbed a bunch of heat.

If someone wants to make this far fridge work even better you would add insulation to the exterior of the fridge so it could use more of its BTUs to take heat from the air instead of combating the ambient outside conditions of the refrigerator.


Another rough calculation is that a 6 lb bag of party ice will take 864btu to melt in a cooler. so depending on your velocity through air piping in the cooler it may have about as much/more energy removal then the bar fridge over a couple hours of cut time
similar amount of energy as running the harbor freight dryer for 1.5 hours.
I would pack the cooler with ice and fill will salted ice water for max heat transfer.

Another expansion of the bar fridge idea ( @DnKFab which is a great diy dryer idea btw) would be using a small chest freezer with a copper tube heat exchanger inside then filling the freezer with antifreeze. the heat transfer rate would be many time higher then air to air heat exchanging while also having a greater delta T.
This setup will likely be able to do longer cutting times then the bar fridge. but with a extreme long cut sessions 6-8-10 hours range you will likely needed to move back to a standard refrigerated air dryer.

another interesting part is the three different type of heat exchangers in these different approaches .

Bar Fridge = Air to Air Exchanger

Freezer with anti freeze = Water to Air Exchanger

Refrigerated Air Dryer= DX (refrigeration) to Air Exchanger

Also both fridge and freezer have a extra heat exchanger step before those btus actually make it to the condenser coil.


Sometimes when I read your posts, I wonder to myself, does your wife and kids know you are exactly what AI will be like in the near future!


Very true, but if the refrigerator has trouble keeping up with the desired cooling, the frozen bottles would easily buy additional “cooling credits.” But if the heat exchange gets the internal temperature of the refrigerator warmer than the point the refrigerator would normally cool, then the warmed water bottles would be a liability (same with just water bottles stored in the frig).

In the case of the refrigerator warming up with time, one could say that would likely happening even with more insulation or without the water bottles.

I do like the antifreeze idea for the better transfer of heat. But adds a messy element.


WE can only hope.


Oh wise and Powerful @TinWhisperer

Have you done the math to see how much cooling the air needs for the plasma cutter to keep going without a moisture issue? The hypertherm 45xp manual calls for a minimum of 6 CFM at 90 psi.

These commercial air dryers are made to pull the water out of high CFM items, like paint sprayers and sandblasters.

As an aside, the water bottles in my fridge are there as a convenience factor since I have the room to keep drink water cool in my fab trailer. If I’m getting extra benefit from the cold water assisting with keeping the internal temperature down then yay.

I wasn’t trying to knock the bar refrigerator set up, it seems like a very decent inexpensive setup for shorter cutting sessions in favorable ambient temperature and humidity conditions. I was just trying to add a little context to the conversation.

Refrigerated air dryers are built to deal with the CFM range and ambient conditions they’re designed for whether that’s high or low. And all these dryers have a very specific operating range( inlet temperature and CFM). Some are designed for 6 CFM some are designed for 9 CFM some are designed for a 100 CFM. One thing refrigerated air dryers do all have in common is they are specifically designed to take thermal energy away from Air in the most efficient way possible. (DX to air exchanger)

I have . Mind you you only can take a look at it as a snapshot in time because throughout the year it varies wildly. When designing your system that allow for it running in summer on a high humidity day with a high ambient temperature while also considering the longest session you have on that day. That hypertherm 6 CFM is a minimum and they also specify an air quality standard. Here’s a post more about the air quality standard that hypertherm requires.

Definitely the water bottles help extend the session time with your setup.

My assessment of the bar fridge scenario obviously rubbed you the wrong way.

Here is a good question.

If a bar fridge with coil of Copper in it does the same job as a small six or nine CFM refrigerated air dryer, why is there not a company making these for quarter or 1/5 the price of a standard refrigerated air dryer and flooding the market?


No, not at all - just adding on to the AI comment from above. :slight_smile: @TinWhisperer is smart…he knows things…This is why a lot of us ask you a lot of questions and seek your help and advice.

The only way I can think of to test and verify is to out a temp sensor inside an airline and find a way to sample for humidity at the termination point after x number of time running.

Before and After real world use in 90* ambient, 90% humidity and my compressor with it’s inherent heat generation of the air after exceeding the recommend duty cycle is night and day.

SO - $?$ on copper tubing attached to the wall, with or without a transmission cooler in front of a fan on the low end, Redneck air dryer in the current conversation timeline as a mid $$$ DIY, or pony up and spend the money on an actual air dryer rated for expected use plus 15%.

Bottom line is something is better than nothing.


@TinWhisperer as our resident bot I think you are going to have to get used to others addressing you as deity. Just one more step down the path…. You have now reached the status of Mindar in Kyoto, Japan and the Bless You Too Bot in Germany.

Lord… I mean @TinWhisperer help us. :stuck_out_tongue_winking_eye::joy:


Remember the story of 01.

To me this feels like one of the most likely outcomes of our creation of artificial intelligence.

This clip begins partway through the story after humankind rejects robotics and artificial intelligence.


No doubt!!! But with the current climate of distrust, it is doubtful that the machines would be totally autonomous as there will always be a greedy consortium of people that will be benefitting and have a back door of influence on the machines.

And, after-all: If someone is smart enough to build a machine that could replicate, learn and be autonomous…they are also smart enough to know that they could eventually be on the receiving end of something they might not like.


After reading most of this thread, I’m just waiting for someone to add nitrous to their compressor :joy:

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