Chiller question and settings

Hey guys,
I got a CW-5200 chiller with my laser and I have a question about ambient temperature. I have been watching a bunch of videos and reading a ton of posts about the chiller settings. A lot of the info I found seems to set the lowest temp to around 15c. Current my chiller shows the water temp when I turn it on it is usually around 10c. I live in the NW and during the winters my shop gets pretty cold. It is an insulated shop so it rarely gets below freezing unless we have a really bad cold front come in. My question is, is it OK to run my laser at this temp, or slightly lower (as the winter progresses) or do I need to think about/consider adding some type of warming element to the mix? I had never heard or thought that this is a thing but I came across some posts today about people setting up automatic heating elements to keep the water from going below a certain temp. So thought I would ask.

Also, what chiller settings would you recommend for getting started? Intelligent or Constant? Low temp/standard temp, etc?

I live in Florida, so take that into account when you read anything I say. First of all, you will want to change it from Intelligent mode to Constant. Intelligent will keep it within a certain range of the ambient temperature. Constant will keep it within the Min. and Max. temperature that you set. There should be a label on your laser that states the safe operating temperature range. I have a 60W OMTECH laser and an OMTECH branded CW-5200 chiller (if yours is an S&A the setup is slightly different), and I have my Min. set to 16c (61 Fahrenheit) and my Max. set to 18c (65 Fahrenheit), the chiller will try to keep it between those two temps. These are the recommended settings that came with my chiller. It works for me.

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Great. Thanks for the info. I think those settings would also work for me as well. But I am not sure what to do about ambient temps that are sub 10c during the winter months.

I remember reading that someone (It may have been Russ) recommended putting a couple 50w lightbulbs under the tube at night. I am thinking if I did that and wrapped the 1/2" tubing in flexible foam pipe insulation and make a insulated cover for the chiller, that should get me through the freezing temps at night. Any thoughts on this idea?

The caveat of heating it, you need to keep the water moving as long as you are heating it…

OMTech coolant that is usable down to pretty low temperatures.

I got mine from Amazon … OMTech didn’t have any…

It is toxic to animals, just like automotive antifreeze.



Just curious. Wouldn’t water flow by itself stop freezing within the system? I think most of us (depending on where you grew up) were taught growing up to drip the faucets at night during freezing temps. Obviously if the temps got ridiculously low there would need to be some additional safeguards put in place.

Yes, but I wouldn’t depend on it… once it finds something to freeze on, it’s on it’s way…

Russ mentioned that the 5200 series produce about 60W of heat via the pump… Of course you’d have to run it all the time it may get cold.

Some people have put aquarium pumps in the tank of the 5200 series and extend the useful range. You still need it circulating…

Good luck


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I deduce that the “intelligent” works in “differential” mode using the ambient temperature or a specific component of the machine as a reference point. This mode allows the fluid to remain a certain value (set point) above or below the reference temperature. This temperature control mode is best suited to avoid the formation of water due to condensation due to the difference in dry temperature and relative humidity, which in some places can be very high.

To prevent freezing I would use a low contraction (10-15%) of propylene glycol as it is very low toxic (assuming it is intended for home use) compared to other types of glycol.
The fluid to be cooled can be subjected to a temperature below 0ÂşC where it is cooled if temperatures close to or below 8ÂşC are requested.

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If there was any chance of water freezing in the tube I’m going to drain it.

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They feed it to milk cows, I hope it’s low toxicity. :crazy_face:

I ran this the first winter I had a machine. I got propylene glycol from the local farmers cattle feed store.

It is pretty thick. I ran about 40% and it slowed my circulation rate by 50% along with produced a massive amount of bubbles. As you can see in this short video.

You can find the percentage of it’s solution with water for what temperature that could reasonably be reached…

The various functions of the 5200 controller allow a pretty wide range of configuration…

It’s explained in the user manual and the maintenance manual.


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I honestly don’t know if it is very or little toxic, I just mentioned what is technically announced by the manufacturers.
What I know from my own experience is that if you ingest it, you will be left vomiting for days. That well-known technique of removing liquid from a tank by sucking a hose can go very wrong. :grin:

I recommend a percentage of 15 to 25% ethylene glycol for my chillers (the same or very similar to that used in cars) for working temperatures up to 7ÂşC. But this is for industrial machines with various purposes:

  • Anti-freezing prevention up to -5/-10ÂşC
  • Anti-corrosion prevention
  • Anti-fungal prevention (including legionella).

For higher concentrations, you need to pay attention to the density of the fluid. Pumps are usually built for the density of water, when they are subjected to fluids with densities identical to those of oil, the flow rate reduces significantly, the pump itself goes into overdrive and ends up burning out if nothing is done to regularize or compensate for the density of the fluid. :wink:

I understand the attraction to this type of equipment (very cheap indeed), however as a technician I shy away from this type of equipment. Often the reliability and cost of purchasing replacement parts make repairs unaffordable.
It’s often cheaper to buy a new one… it’s not my style. :worried:

The controller used is a “disguised” multifunction one from Dixell
, this one actually quite basic. But for the device it is intended for, it is already very good. Perhaps the most reliable and easily replaced component in the entire machine., this one actually quite basic. But for the device it is intended for, it is already very good. Perhaps the most reliable and easily replacement component in the entire machine. :grin:

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In my research I came across the Secret Recipe that was posted in these forums.

Final recipe with Glycerin added.

if using Tetra, then you don’t need Bleach.

From this post:

I am working on a method to hopefully eliminate the risk of freezing without any additives but if I am not opposed to adding something that is proven and will not screw up my system.

I am wondering if anyone has tried (or currently using) this recipe and/or what your thoughts are? I ask because this is from a post back in 2021 and I am not sure if this recipe has been proven ineffective or not since then.

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As far as I know it’s physics when something freezes. Using something besides water?

Keep in mind the dielectric constant when you mix stuff up…


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I understand what most of the settings do and what they are for. I was just hoping to get some input on which settings are best and why. An example is the Intelligent vs Constant mode. Being new to CO2’s I really did not know which mode is the best mode to use, and why. Another is the temp settings. I know what they are for but I did not really know where to start and why.

I am starting to understand them better now.


No. I am just working on a way to add more environmental control in my shop as well as water flow. AND having a backup plan in place in case I lose power for extended periods of time. But I know that nothing is fool proof so I am just wondering if there are any good, safe additives/recipes that have been proven and can be added as a backup backup plan.
But honestly if we had a really bad winter event where we could be without power for extended periods I would probably just drain the tube. But it doesn’t hurt to educate myself.

Been a radio operator for decades… We do our best to avoid lightening strikes… they do occur.

All you can do it the best you can.

If you live in different latitudes/longitudes you’re requirements will be different. I found a rare low temperature and based requirements on that.

That’s what I’d suggest…


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Exactly my thoughts. We get some freezing temps every year, but usually not too crazy. But every once in a while we get hit pretty hard. And have had power outages for almost a week during sub-freezing snow events. In those situations I will just empty the tube. Oh that reminds me, is there a certain way to do that correctly? Sorry if that is a dumb question.

Hi Shawn,
It’s pretty straight forward. remove the drain plug out of the chiller tank and drain the tank. loosen the filler cap on the chiller so it will fully drain. If the chiller is lower than the tube and the lines are run under the tube most of the water should drain out of the tube. If the chiller is elevated above the tube you will have to disconnect the hose on the outlet side of the chiller to let the tube drain.

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Thanks Rob. I was hoping it was easy like that.

My chiller is under the machine. I drain it, but it doesn’t drain the coolant from the tube itself.

Be nice if yours does. I’d try it and see if it drains your tube…

I find it’s easier to just take it out and point one end up… they are clear, so it’s not rocket science to tell when it’s empty… :crazy_face:


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