Refrigerated air dryer needed. Which should I stay away from?

DanASM · Aug 15, 2021

I see SCHULZ 20 CFM REFRIGERATED COMPRESSED AIR DRYER 115V, FOR 5HP COMPRESSORS MAX | eBay

Its new, but cheaper than most. Is it a red flag? Should I chance it with a cheaper one or should I look for a much better one?

I see Ingersoll Rand ones for a decent price, but I think the brand has gone downhill over the years. Might be a hobby grade.

Kaeser TX3 15 CFM Refrigerated Compressed Air Dryer 3 Available | eBay This guy has 3 of these. That price looks good. I only need 15-20 cfm.

I just got my first cnc lathe moved into place and I dont want to chance it with any wet air. The machine ran oil over its lifetime. Looks pretty good for a 1 shift machine for 25 years of production.

Its like I am 16 again and just got my first car. I want to take as good care of it as I can.

moonlight machine · Aug 16, 2021

DanASM said:
I see SCHULZ 20 CFM REFRIGERATED COMPRESSED AIR DRYER 115V, FOR 5HP COMPRESSORS MAX | eBay

Its new, but cheaper than most. Is it a red flag? Should I chance it with a cheaper one or should I look for a much better one?

I see Ingersoll Rand ones for a decent price, but I think the brand has gone downhill over the years. Might be a hobby grade.

Kaeser TX3 15 CFM Refrigerated Compressed Air Dryer 3 Available | eBay This guy has 3 of these. That price looks good. I only need 15-20 cfm.

I just got my first cnc lathe moved into place and I dont want to chance it with any wet air. The machine ran oil over its lifetime. Looks pretty good for a 1 shift machine for 25 years of production.

Its like I am 16 again and just got my first car. I want to take as good care of it as I can.

You can't miss with Kaeser. My first car was a Studebaker Lark. 283 Chevy engine, it was pretty quick for a stodgy old four door. At 16, I used to practice my drinking and driving in it. If you just ever so slightly let it rub on the concrete divider wall you could get about 250' of sparks! Best done at night!

Larry Dickman · Aug 16, 2021

I have a couple Speedaires, they work flawlessly all day everyday. You can't go wrong with a Kaeser either. I've never heard of a Shultz. Looks like they cause cancer if you use it in California, so you should be ok.

FredC · Aug 16, 2021

I am using a Parker made in Italy I think rebranded Starlette. Not even a hiccup in 7 or 8 years of use. The one thing with this unit is there is some condensation on the pipes and such. It will drip off and make a spot on the floor. I mounted mine on the wall and have a pan with a drain under it. It collects about a quart every couple of months. You will need a tube through the wall to vent the condensation collected from the compressed air. The thing ejects that under pressure every 15 minutes or so in a split second blast. Less noise inside when it exhausts and also less humidity in the building.

Orange Vise · Aug 21, 2021

DanASM said:
I see SCHULZ 20 CFM REFRIGERATED COMPRESSED AIR DRYER 115V, FOR 5HP COMPRESSORS MAX | eBay

Its new, but cheaper than most. Is it a red flag? Should I chance it with a cheaper one or should I look for a much better one?

Our Kaeser dryer died after 3-1/2 years of service. Kaeser's techs said it would cost more to repair it than buy a new one.

We now have three of those Schulz units. They're made in Italy, supposedly. First one has been in service for 6 months so far and working well. Time will tell.

At 1/4 the price, it just needs to last 6 more months to "break even" with the Kaeser (even then, it's actually ahead if you consider time value of money). We bought em under the premise that they'd be semi-disposable, but keeping our fingers crossed that they'll last a few years. They run 24/7/365.

20CFM is a pretty small dryer. If your compressor is right around 20CFM, I'd step up to at least the next bigger size, if not two sizes bigger. The rated capacity is in ideal, cool conditions and it drops in more real world conditions. Unlike the compressor, where sizing it too big causes on/off cycling issues, dryers are "always on" with only a minor cost penalty in unit cost and power when you size up.

tmt · Aug 22, 2021

Orange Vise said:
Our Kaeser dryer died after 3-1/2 years of service. Kaeser's techs said it would cost more to repair it than buy a new one.

We now have three of those Schulz units. They're made in Italy, supposedly. First one has been in service for 6 months so far and working well. Time will tell.

At 1/4 the price, it just needs to last 6 more months to "break even" with the Kaeser (even then, it's actually ahead if you consider time value of money). We bought em under the premise that they'd be semi-disposable, but keeping our fingers crossed that they'll last a few years. They run 24/7/365.

20CFM is a pretty small dryer. If your compressor is right around 20CFM, I'd step up to at least the next bigger size, if not two sizes bigger. The rated capacity is in ideal, cool conditions and it drops in more real world conditions. Unlike the compressor, where sizing it too big causes on/off cycling issues, dryers are "always on" with only a minor cost penalty in unit cost and power when you size up.

That's really sound advice on up-sizing the the dryer!

How much you up-size the refrigerated dryer kinda depends where you have the dryer located. If the dryer is after the storage tank, keep in mind that the tank doesn't care what the pump is putting out, it will output air as fast as the demand until it runs out. That flow may far exceed the capabilities of the dryer at times.

The other method is to place the dryer before the storage tank. That way the dryer only processes what the compressor pump is capable of outputting and not what the tank is capable of outputting.

In either case if you don't have an after-cooler on your compressor then you will need to get a dryer capable of accepting high inlet temperatures. Those cost considerably more, a better choice is to put one on. Another thing about a dryer, some come with a built-in coalescing filter, some don't and are priced accordingly.

I don't believe that Kaeser makes their own dryers. Looking at the their pictures of them on their website, they look exactly like Hankison dryers, so do a lot of other private brand dryers. I am not sure that they are still called Hankison anymore. Seems to me that they merged or were bought out by a British firm a few years back.

M. Moore · Aug 23, 2021

I have a Kaiser and have had no problems. I don't run it all the time it is an on-demand system. I installed a special flow switch in the line just past the dryer. The switch turns the dryer on and a timer keeps it on for 20 minutes when there is enough flow in the line. So if I quickly blast some chips off the table the dryer will not come on, if I blast the chips off the mill and clean the vise etc for at least ten seconds then the dryer will come on and run for 20 minutes.

So in exchange for not running the dryer 24/7 I get the occasional 20 minute run time. If I am using the compressor enough that I drain down the tank and the compressor cycles then the dryer will automatically be on and running when needed. There are some weeks when I don't even cycle the compressor once and there are some days when I am blasting that I cycle the compressor a lot of times in a day. I have never had a drop of water in my system.

The dryer is set up after the compressor and "wet" tank and before the "dry" storage tank. I think it is lame that the manufacturers of the dryers fail to include an on-demand switch and timer to run the dryer when it is needed. When I bought it the Kaiser dealer said " just turn it on in the morning and run it all day"! Duh? Why?
The company I bought the flow switch from said that the most common use for their switch was running a dryer.

We run our fridges 24/7 because we need to keep the contents cold, running an air dryer all the time is a total waste as there is no benefit unless wet air is passing through.

I have a 20 horse compressor and the matching CFM dryer which is rated just above the output of the compressor. It works just fine and I have had no problems. The only problem I had was right at the beginning a few weeks after installing I noticed something was wrong and when I checked the system the installation instruction papers had fallen off the top of the dryer and stuck to/covered the cooling fan inlet on the dryer. This caused the dryer to overheat and it went into automatic shutdown. I had to re-set the dryer which was a bit of a pita given the location of the re-set switch but since then there have been no problems and that problem was a crazy fluke.

M. Moore · Aug 23, 2021

I also forgot about the interlock for the compressor pressure switch. Unless the dryer is on and running the compressor will not come on as the pressure switch is disabled unless the dryer timer switch is on. This works very well and is a great way to have my compressor in the "off" state all the time unless it is needed. I chased down all the leaks in the system so that it would not drain down overnight, that is two 120 gallon tanks that take almost 5 minutes to fill so I did not want the system to drain down at all. It took me quite a while to find all the leaks but eventually I fixed all of them and the worst offenders were the air blow guns that leaked from brand new out of the box! Damn that is annoying.

My blast cabinet air system leaks a little bit and I turn it off after use but if I forget then the system will drain down to 1/2 or less overnight but the compressor does not come on, which is very nice because noise is an issue.

Quick tip- if you want to test your blow guns just dunk them in a bucket of water, same goes for the quick connect fittings. These often leak just a small amount, not enough to hear the shuh sound but enough to be annoying. If the pressure is down even a few pounds overnight I know something is leaking.

gustafson · Aug 23, 2021

Compressed Air Dryer

hell I bought this one in 2003 and took it out of service ~5 years ago still working fine. It is in my garage now and seems to still work as of last fall

I was gifted a Zek to replace it and it works great.

DanASM · Aug 23, 2021

I would think they arent very hard to build. Even a cheap one would most likely be cost effective, even if it dies early.

I only have a small cnc lathe that needs air. The rest of the shop is just blow guns. Compreesor is 5 HP. I think the old one was 7.5HP but had its 3rd 5 HP motor on it before we sold it.

I want to add another tank to keep pressures more consistent (90-100psi). I talked myself out of a screw compressor due to not needing that much air. I have a tight system for the most part. 1 Cheap blow gun ruined it for the rest though. I need to get a better blow gun and a good dryer.

The Kaeser from the OP is in PA and I am in MA. Shipping shouldnt be bad for that. I wonder if that 15 cfm would be too little for me? I want to add more machines later that would need the air, but it still wouldnt need that much cfm overall.

DRY ids the key word now. The gun closest to the compressor might as well be a garden hose lately. 100' down the building at a slight incline and we got plenty of dry air all day long.

Time to make much needed ugrades.

jerholz · Aug 23, 2021

Why not just run another 100 feet of pipe from where the air is dry back to where you need dry air?

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CarbideBob · Aug 23, 2021

DanASM said:
I would think they arent very hard to build. Even a cheap one would most likely be cost effective, even if it dies early.

.

All kinds of things.

DDoug · Aug 23, 2021

CarbideBob said:
All kinds of things.

If you put that coil in a bucket of prestone inside the fridge, it would probably work even better.

Hillside Fab · Aug 23, 2021

M. Moore said:
I have a Kaiser and have had no problems. I don't run it all the time it is an on-demand system. I installed a special flow switch in the line just past the dryer. The switch turns the dryer on and a timer keeps it on for 20 minutes when there is enough flow in the line. So if I quickly blast some chips off the table the dryer will not come on, if I blast the chips off the mill and clean the vise etc for at least ten seconds then the dryer will come on and run for 20 minutes.

So in exchange for not running the dryer 24/7 I get the occasional 20 minute run time. If I am using the compressor enough that I drain down the tank and the compressor cycles then the dryer will automatically be on and running when needed. There are some weeks when I don't even cycle the compressor once and there are some days when I am blasting that I cycle the compressor a lot of times in a day. I have never had a drop of water in my system.

The dryer is set up after the compressor and "wet" tank and before the "dry" storage tank. I think it is lame that the manufacturers of the dryers fail to include an on-demand switch and timer to run the dryer when it is needed. When I bought it the Kaiser dealer said " just turn it on in the morning and run it all day"! Duh? Why?
The company I bought the flow switch from said that the most common use for their switch was running a dryer.

We run our fridges 24/7 because we need to keep the contents cold, running an air dryer all the time is a total waste as there is no benefit unless wet air is passing through.

I have a 20 horse compressor and the matching CFM dryer which is rated just above the output of the compressor. It works just fine and I have had no problems. The only problem I had was right at the beginning a few weeks after installing I noticed something was wrong and when I checked the system the installation instruction papers had fallen off the top of the dryer and stuck to/covered the cooling fan inlet on the dryer. This caused the dryer to overheat and it went into automatic shutdown. I had to re-set the dryer which was a bit of a pita given the location of the re-set switch but since then there have been no problems and that problem was a crazy fluke.

Did you try following the dealers advise?? I have a Zeks, and if the air isnt running, it only cycles maybe once every 2hrs for a couple minutes. I leave it on all the time because when it's hot in the shop it takes 15-20 minutes for the dryer to chill down to its operating temp, and until then I get some condensation in the air.

dkmc · Aug 23, 2021

Hillside Fab said:
Did you try following the dealers advise?? I have a Zeks, and if the air isnt running, it only cycles maybe once every 2hrs for a couple minutes. I leave it on all the time because when it's hot in the shop it takes 15-20 minutes for the dryer to chill down to its operating temp, and until then I get some condensation in the air.

Sounds like you have a cycling dryer and M Moore has a non cycling drier that he has converted to a cycling dryer. His normally would run the compressor all the time it's switched on. Yours cycles on and off.

dkmc · Aug 23, 2021

I've recently picked up two dryers, an IR 300cfm for blasting and a Pneumatech 60cfm for general shop air treatment. Both are non cycling and I've been thinking about how to convert them to cycling units. Would you please consider further explaining the technical details and part numbers/ source of the flow switch and interlock setup? I would be keenly interested in that info.

M. Moore said:
I have a Kaiser and have had no problems. I don't run it all the time it is an on-demand system. I installed a special flow switch in the line just past the dryer. The switch turns the dryer on and a timer keeps it on for 20 minutes when there is enough flow in the line. So if I quickly blast some chips off the table the dryer will not come on, if I blast the chips off the mill and clean the vise etc for at least ten seconds then the dryer will come on and run for 20 minutes.

So in exchange for not running the dryer 24/7 I get the occasional 20 minute run time. If I am using the compressor enough that I drain down the tank and the compressor cycles then the dryer will automatically be on and running when needed. There are some weeks when I don't even cycle the compressor once and there are some days when I am blasting that I cycle the compressor a lot of times in a day. I have never had a drop of water in my system.

The dryer is set up after the compressor and "wet" tank and before the "dry" storage tank. I think it is lame that the manufacturers of the dryers fail to include an on-demand switch and timer to run the dryer when it is needed. When I bought it the Kaiser dealer said " just turn it on in the morning and run it all day"! Duh? Why?
The company I bought the flow switch from said that the most common use for their switch was running a dryer.

We run our fridges 24/7 because we need to keep the contents cold, running an air dryer all the time is a total waste as there is no benefit unless wet air is passing through.

I have a 20 horse compressor and the matching CFM dryer which is rated just above the output of the compressor. It works just fine and I have had no problems. The only problem I had was right at the beginning a few weeks after installing I noticed something was wrong and when I checked the system the installation instruction papers had fallen off the top of the dryer and stuck to/covered the cooling fan inlet on the dryer. This caused the dryer to overheat and it went into automatic shutdown. I had to re-set the dryer which was a bit of a pita given the location of the re-set switch but since then there have been no problems and that problem was a crazy fluke.

Hillside Fab · Aug 23, 2021

dkmc said:
Sounds like you have a cycling dryer and M Moore has a non cycling drier that he has converted to a cycling dryer. His normally would run the compressor all the time it's switched on. Yours cycles on and off.

I thought we were talking about refrig dryers here per thread title. IDK why any refrig dryer would use air all the time.

I suppose if he has a heatless desiccant dryer that would make sense. I wouldnt think Kaiser would be selling those for a 20hp compressor in recent years, unless a very low dewpoint was needed?

Edit...maybe you meant the dryer cooling compressor. I'm not an expert, but wouldnt one freeze up if it just ran all the time with low air demand? And wouldnt the way M Moore described letting the cooling coils heat up to 100f not really do anything for extracting condensation for the first xx minutes it kicks on?

Edit 2, after some googling, I guess I stuck my foot in my mouth. I picked mine up used, and just assumed thats how they all worked.

DanASM · Aug 23, 2021

jerholz said:
Why not just run another 100 feet of pipe from where the air is dry back to where you need dry air?

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I have thought about this in the past. My problem is the lines already have rust in them from the last 30 years. I want to start fresh and keep things clean. Even though I get dry(er) air at the other end of the building, I get sandblasting sometimes out of the blow guns. I dont want any air tools or anything getting that crap jammed up in anything.

DanASM · Aug 23, 2021

I am now checking out cycling vs non cycling dryers. I feel like I would want/need a cycling dryer, but as I read more about non cycling ones I dont see myself having many concerns.

We do use the blow guns to blow off large batches of screw machine parts, clean off screw machines, Blow out tool holders, etc. What I am getting at is how much I will actually use for CFM. I can use quite a bit at times and the compressor cant keep up. Other times its only for a few short bursts here and there and wont be needing much.

When I do need air all of a sudden and a lot of it is what I want to prepare for. If 2 people are using air at the same time it can drain quickly. I want to add another tank for more flow, but keep the 5 hp compressor. We dont use the air all day long, so there are plenty of times for it to fill back up slowly.

I just want dry air all the time, whenever I want it. Dont want to undersize anything either.

Great topic so far. I am learning a lot. Thanks for the support.

Pete Deal · Aug 23, 2021

I bought about a 25cfm noncycling dryer a few years ago. My air system is pretty well designed but I still had water in the system. No more since installing it. I think mine is a hankison. It’s very simple design. Two coils of copper pipe run together. One is air one is refrigerant. There is a moisture trap at the bottom and a blow down valve with a timer. I did notice when I bought it that some brands of similar design use aluminum coils. I think I got mine from zoro.

Refrigerated air dryer needed. Which should I stay away from?

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