Air Supply Chiller Choices

Thoughts on choosing a refrigerated air supply drying setup for the shop. February 20, 2011

I am planning on upgrading from an elaborately wound copper pipe air supply to one with a chiller. The chillers all seem very pricey. Any suggestions on a basic unit? Seems like there should be an inventive way of adding a long chilling cuff to the existing piping and away you go. I have a 3hp Colombo and would really like peace of mind that I'm not fouling it up. I do have a couple of inline separators, but one never knows.

Forum Responses
(CNC Forum)
From contributor B:
About 6 months ago my chiller died and I spent 6 weeks sorting out a new one. This is for a 10hp HSD spindle and a 5hp compressor. The chiller was at the compressor, so it took care of the entire air system in the shop as well as protecting the CNC spindle.

I settled on a unit from McMaster-Carr. It's a Parker/Dominik-Hunter unit and costs about $650. I'd had a lot of trouble with my old unit over the years and was trying to find something both economical and reliable. They were competitively priced and it was here in one day.

Some of these units now are recommended by the manufacturer to never be turned off. I'm not quite sure why. The Dominik-Hunter tech people said there was no problem putting theirs on a timer as long as it turned on early enough in the day so that it is drying the air before we turn on the CNC. As such I have the timer set to have the unit on from 6am to 6pm each day. This cuts the wear and tear as well as running costs by 50%.

I mentioned at the outset that I spent 6 weeks without a chiller while I sorted this all out. I figured I had mechanical dryers around the shop and a very large one at the CNC so I would be okay in the short run. Well... that wasn't quite true. I have a lot of air cylinder activated dust gates in the shop, and the wide belt has an air activated brake. By 6 weeks of no chiller these were all mucked up and failing. I had to take a lot of the solenoids apart and clean them out. As far as I can tell there was no damage to the HSD spindle, but I'm still keeping my fingers crossed.

So by my experience I'd say not to procrastinate. Make the investment (sized to your compressor HP) and properly protect your CNC.

From contributor R:
Are you guys talking about an air drier?

From contributor B:
Yes, refrigerated air dryers.

From the original questioner:
Thanks. I'll get on your suggestion right away. The price sounds reasonable, as I was quoted two grand by a local supplier.

From contributor M:
When you shop for a drier, make certain you size it properly for your CFM and consumption. Don't buy the cheapest, but it's not necessary to buy the most expensive either. Over time you'll find that the benefits are huge regarding service, repairs, and replacement of valves for all your tools.

From contributor J:
I agree with contributor M as to the correct size dryer. I looked at Mcmaster Carr and the dryers in the $600.00 range are only rated at 5 CFM. This seems low. I would think you would need more. I have a dryer I think rated at 35 CFM with a 5hp 80 gallon compressor - works great. I would also highly recommend an automatic drain on the tank. This has made the biggest effect on getting the water out of the system for me. That and I also have two filters before the dryer, one of which has a float type drain in the bowl. I figure get as much water out of the system before the dryer so it can be more effective.

From contributor B:
Contributor J is right on the McMaster dryer. I looked back and I spent more than the $600 I was remembering. I bought the 15 CFM unit for about $850. Sorry for the error.

I went with the slightly undersized unit for our compressor due to the large price jump to the next size and the fact that we rarely if ever press our compressor to the limit. The compressor has the capacity to push 20 CFM, but our actual needs seem to be well below the 15 CFM of the $850 unit.