Chiller for 5L rotovap

I’m new to posting here, just came over from ICMAG. A little background info, I am a small scale farmer who up until recently was stuck in the Stone Age open blasting with butane in the backyard. My lackluster product and an ever more competitive market demanded an upgrade. After a few weeks of reading and inspiration I have completed some small scale ethanol extractions and am ready to go full scale.

On to the question, I am about to receive a 5L rotovap from usalab, I plan on using it to recover Ethanol post extraction/filtration.

I didn’t budget an additional 3k+ for a chiller. I was hoping for a DIY method to get me through the first couple runs until I can justify spending on the chiller.

From my understanding the vacuum level/water bath/chiller temp work in relation to each other, would it make sense to run a deeper vacuum and lower water bath temp(27-30c)in order to put less stress on the chiller?

Is it possible to recirculate liquid through a chilled reservoir and then the condenser coil?

What temps should I aim for?

What liquid/cooling method would you use?

Is this a bad idea? Should I just buy a chiller?

Is there a formula for sizing a chiller to rotovap?

Thanks in advance for any help!

Dont worry it can be done! U want ALOT of ice packs and a bag of ice to start. Put an aquarium pump into an igloo/ice chest. Fill the chest with ice to start, then as ur liquid line gets too high to add more ice, start using the ice packs. U want to see like a 30C difference between ur bath temp and the chest temp. If u have a well, u can pump cold water through a faucet into ur coil and out into a water resevoir or w/e u would use excess water for.
For more fun u can use dry ice instead of ice packs, but make sure ur lab is well ventilated cuz thats alot of co2 constantly being produced.
I had about 20 ice packs from walmart that i cycled throughout my day, with alittle addition of dry ice here and there.
Another place to look is ebay, make them an offer and low ball them
That 5l is rated for 4l/hr bur expect like 1.5l/hr without the proper chiller
Running the vacuum too strong can cause some unexpected pops and bumps that may pop over and taint ur precious clean alcohol. I keep mine around 0.75-0.85

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There are 2 very cheap options.

1 is using the faucet for your cooling needs

2 is using an aquarium pump, bucket, and ice water.

Just a heads up, I’ve done both. My 315gph pump didnt have enough ballz to get the water moving. Hoping this new 400gph pump will suffice.

Almost forgot, good luck getting all the damn sawdust out of the condenser. I used an air compressor for a little help. Tape over the inner coil inlet/outlet so you dont get sawdust inside. It’s a bish to fully remove


Thanks for the input! I am thinking a saltwater/ dry ice slurry inside a party cooler.

If your 400gph pump doesn’t have enough head pressure you should switch to a diaphragm pump, high pressure low volume.

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Sawdust? Where is sawdust coming from?

How did it turn out? Currently crossing the same bridge as you and I would really appreciate the feedback… keep bouncing back and forth on what to do… Working it from a few angles to get it figured out.

Working on a deal in China, bidding low on Ebay and considering DIY concepts with a copper or stainless steel coil dropped into an ethanol / dry ice slurry.

a diaphragm pump is far better suited for a DIY chiller then a submersible first of all a submersible dissipates its heat into its surrounding. not only are you having to cool the load imparted on the condenser but you are now also cooling the load of the submersible pump itself. For our application 1 to 2 gallons per minute at 30 PSI is far better than what a submersible low pressure pump can achieve.

I had no problems using regular ice blocks and keeping my cooler recirculation water at a constant 5 degrees Celsius I did have to keep swapping in new ice blocks every so often


They fill the condenser up with saw dust during shipping to protect from breaking.

I used my.air compressor to blow out the saw dust.

Do this outside, theres quite a bit


The sawdust is packed in the condenser, compressed air will make it easier for sure.

I am currently using a party cooler and ice with a small submersible pump, it works well for now, but as soon as the ice melts ethanol recovery slows to a crawl.

eBay is a good source for used chillers, I have a simple design to automate my rotovap, and a chiller is going to be necessary if I want to run it all night unattended.


Good tip. I have been looking into diaphragm pumps quite a bit, both for moving coolant solution and solvent, do you have any suggestions?

Price is holding me back on that because at this point I need a chiller, not a pump and it is hard to spend $300 or more on a pump to build a chiller to ‘save money.’ Makes me think it would be more effective to spend the $1000+ or so on a less expensive / used chiller and not have to stress it so much. Just cuts into my budget everything else ha

I bought a 35 dollar 40psi 1gph diaghragm pump on and it’s going strong.

Actually it may have been amazon


Thank you, I have been watching Ebay and have been close on a few. I didn’t pull the trigger because the ones in my price range only go down to about -5C. I could use a little guidance…

I know there is a correlation between the efficiency and speed of your roto and the chilling capabilities of your chiller. My question is, is it really necessary to be able to hit -40, -30, -25C from a chiller standpoint, or can you operate efficiently with something less robust.

Thank you! I saw you said that in another thread but its def not amazon, i fux with amazon and haven’t seen it, I’ll check Zoro! Boom!! Just found it, thank you!! :boom:

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Make sure it’s a 120v lol they have a 12v too on zoro

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This should do it.

As far as the temp difference between the condenser and the water bath, I’m sure there is a point of diminishing returns. I also think vac depth plays an important role.

My aim is to make high quality shatter, and preserve terpenes, having my water bath at 45c I feel is too high of a temperature for this.

If I could get my condenser down to -20c and run my water bath around 30c I should be able to achieve my goals.

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thats the same pump i have. i paid like 50 its gone up lol but its a good pump ive beat the shit out of it so far