Can I run automotive antifreeze through the coil of the condenser in a Rotovap ?

I want to know if this is doable before doing the experiment since I will be using a regular water pump to push the antifreeze through the coil, I know antifreeze and plastic dont get along so I dont know if it will damage my pump or even if it would work at all.

If there is any other cheap option besides to automotive antifreeze please let me know

What is this “regular” water pump you’re planning on using?


Ethylene glycol/water mix is usual for industrial scale chillers.
The stuff made for this service has inhibitors to prevent corrosion but so does regular anti freeze.
Dowtherm SR-1


This is a pretty common method for people trying to get up and running on a budget. Some people use sump pumps for this application, i’ve heard of other people getting away with aquarium pumps. Keep it cheap, expect it to break. When you find one that works the way you want, buy a backup for when that one goes down. Also, HF insurance might not be a bad idea.

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Thanks man, thats exactly what I was looking for

My bad bro, I meant to say aquarium pump, since I use them all the time they are the regular pumps for me lol :slight_smile:


Look at the temp you want to run at. If you can swing it run a propylene glycol water mix. It’s food safe and won’t cause a big mess if you contaminate your feedstock with it. It’s still fairly cheap too.


I used a 15 gallon plastic tub for my reservoir along with an aquarium pump and plain water, I would just use frozen water bottles and a laser thermometer to check my temp. When the water bottles unfreeze take them out and put new ones in.
Pretty crude setup but it’s easy and it works.
It’ll be what you do when your chiller breaks anyway

Is there a reason normal antifreeze can’t be used?

I used a cheap amazon submersible pump for ten months straight with zero issues

Make sure the head height is high enough


Does it make a difference to make a hybrid coil of copper coiling (submerged in a cooler box) and silicon (or appropriate for temp) to the fish pump? I heard the copper coiling gives you faster cooling response/ramp.

I used vinyl and insulated it.

You want something that doesn’t sweat Btus to atmosphere.


Use a parts washer pump they are made for pushing thick sludge and they are explosion proof.

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It ruins the seals on lost chillers and voids warranties on some.

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I used to run a custom chiller than ran antifreeze.

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You could just run it with a recirculating pump in a 5gal bucket and freeze the antifreeze with dry ice. Careful, it will turn to sludge, also you need a beefy pump.

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I have automotive antifreeze rubbing thru my rotovap condenser and chiller. Biggest problem I have is getting it cold. Uses quite a bit more water than other mixes.

You can buy cryotek from lowes and home depot wherever you find boiler and home winterizing sections in the store. Mix with water in a factory recommended ratio and it will get you by in a pinch for most rotovap operations.

Like all glycol mixtures its only good down to certain temps. You DO NOT want it to turn to sludge. That higher viscosity cold sludge is going to reduce your heat transfer considerably, if you have this issue then bump the temp up a bit. A chiller running smoothly at 4c is going to be better than a sludgy one at -10. Heat transfer is not just about the fluids ability to absorb energy but also the systems ability to cycle coolant through the lines and heat exchanger in the chiller efficiently, otherwise your condenser in the rotovap its self will loose some heat exchange capacity.


That’s what I meant. “Careful, it will turn to sludge”