I ended up moving my cooler to post tank. All the evidence for the slowing of my compressor pointed to increased back pressure.
Definitely back to normal operating speed. I haven’t measured temp impact yet because I haven’t rewired the fan motor. Need to decide strategy: run fan all the time I am cutting; tie into trigger signal and send to relay to operate fan.
Thanks for the update! Looking forward to hearing your results.
thanks…was fun to make
so one small drawback to your setup…it looks like , as you said, the cooler is post tank…meaning all your hot compressed air goes to the tank before it goes to the cooler set-up…
Am I correct in this?
The problem with this is the air is already greatly cooled and condensed in the tank before it get to the cooler…
my cooler is between the compressor and the tank…my temp from entry into the cooler to exit of the cooler is over 50 degrees C…
How I control a wall mounted fan is with this unit…
the temp probe goes on the line coming out of the compressor head…so as soon as the compressor comes up to speed and the pipes get hot the fans come on cooling down the wall pipes…and even though the compressor may stop…the fans keep cooling till the pipes are back to room temp…
If you read my previous post you’ll see I had it installed between the compressor and the tank, but the back pressure was slowing the motor down considerably. It was slowing to the point I was concerned about damage/overheating.
BTW, there are folks on this site that think post tank is the best approach because compressor manufacturers design the tanks with a drain assuming considerable temp drop/condensation. The thinking is why not take advantage of this and use secondary systems to glean additional benefits. Seems this topic is like the “how often/what weight oil change” threads on truck websites: everybody has an opinion. 
For reference for anyone considering this type system, here are the specs on my compressor. Your results may vary.
I am going to soon be replacing this compressor with a twin cylinder 80 gallon unit and will probably go to the post compressor-pre tank method. Just a few months away.
I’m one of the people that believe that.
I think the benefits of having it after the tank out weigh the benefits of having it before the tank.
I have the compressor you are looking at upgrading to in essence. I have my cooler between the head and the tank. lots of debate there. @TinWhisperer if for example…the tank does 60% of the job… Im hoping that my order of plumbing is doing more like 80-85%. Those are just random numbers to go with the 60% concept…but my concern is that the chance to get the extra 20 to 25 percent is lost since you dong have the heat diff placing it after the tank. just musings of a random mind.!
so I have mine setup with a check valve just after the compressor head just like it does on the compressor with a release valve on the check valve just like the one originally installed on the tank…
on standard compressor set-up there is a check valve with a pressure relief that drains the pressure off the heads when it stops…I have installed a very similar setup between the compressor head and the beginning of my cooling loop…I am blowing off about 2’ of 1/2’ copper pipe so there is not any back pressure on the head.
My cooling loop works exactly the same as the air coming off the head as before…the head bui;ds pressure from zero till it passes the pressure on the check valve.
I thought this was the way everyone was doing it…
I will admit that the first set-up I had did cause the release of air for the whole cooler when the compressor stopped…as this was a waste of compressed air I re-worked the system for a real showt blow off line like the original compressor design.
I have my check valve where it originally was. I do lose the compressed air that is in the cooler each cycle but it feel its really not significant. Having the check valve here does insures my compressor has even less startup resistance than without the cooler as there is more space for the motor to get up to speed re pressurizing that cooler before the head sees any back pressure. I checked motor draw amps before installing cooler and after and i see no difference at all on draw.
so another part of this is why I have what we used at the Hospital for cooling shop air…compressor to radiator fan cooler…to wet tank…from wet tank to refrigerated dryer…from that dryer to a dry tank…
same system I have but on smaller scale…
i have a medical grade dental air compressor that is plumbed that way as well. minus the wet tank.
It would sure be nice to be able to lay out both ways and do all the math and see how it actually ends up.
I guess in the time being we’ll each have our own opinion of the best way to tackle this issue.
I see what you are saying, and I had left my check valve in the original location. You’re probably right and that is why the back pressure was causing me problems.
I hope you smart guys figure this out before I get that upgraded compressor in a few weeks so I’ll know which way to go!
I have a friend who is a really talented engineer, and I am going to get his opinion before I plumb my next system.
i was really tempted to try to measure captured by tank vs captured by cooler. I ultimately decided it was a fruitless endeavor for how much condensation would potentially be stuck to the surface of the inside of the tank.
I purchased a Arrow Dessicant filter/dryer model B601908. I currently have a 7.5HP Polair compressor and a refrigerated dryer. I have a motor guard filter that serves the table only. This dryer will serve the table only. After I get it installed I am going to track its performance.
You might want to take a peek at the instructions at the bottom
It might be awhile before I get it installed.
Do you have part #s for the two filters before your desiccant?
No, I don’t, burned the paperwork, I bought as a whole unit minus the motor guard.
The first is a filter.
And the second is a coalescing filter.
It looks like it’s sold as a four stage assembly not as individual components.
Arrow is the brand pictured above but another brand name it’s sold under is the
HTP America Max dry
