Ask anybody about doing ethanol extraction at home, and somebody’s going to tell you to just get a rotovap. Time to dispel some nonsense.

Rotovaps are great, in the right space, for the right people. They look so cool and so science-y with the spinning glass and the big coiled condenser. For small batch at home, though, they’re not the best answer, and there’s a lot more to the story than the rotovap itself. I set one up to show you the whole thing.

That “2 liter” rotovap holds about 1 liter

The 2 liters is the flask size. The flask sits at an angle in the water bath, so you can only fill it about halfway. If you overfill it or let it bump, it bubbles up and shoots right through into the rest of the glass. Realistically, you’re running about a liter at a time.

The 1 liter vessel on my setup holds about 1.25 liters with the Flow Port.

What it actually takes to run one

Buying the rotovap doesn’t get you running. You need a chiller or a circulator pushing cold liquid through the condenser the whole run. People will tell you to just use a water circulator. It works, sort of. It gets hot, it’s slower, and it’s more water to mess with.

Then there’s the vacuum pump, which runs constantly. Since it’s running the whole time, ethanol vapor heads straight for it, so you need a cold trap. Somebody will tell you that you don’t need one. Run ethanol through your pump and see how long it lasts.

Leaks are common, so you need a vacuum regulator too. Add the chiller tubing and the vacuum lines, and you’ve got tubes all over the place, plus a lot of things to keep track of.

My rough number for a proper setup is somewhere around $4,500 to $7,800. One of the big sellers lists a 2L turnkey bench around $9,900, and that’s before the cold trap and regulator. All that for about a liter at a time. Pretty crazy.

Glass everywhere

Count the glass on one of these. Condenser, flask, receiving flask, the vapor duct, and a bump trap, because bumping means you need even more glass. Every piece costs money, and every joint is one more place to leak.

I broke a brand new piece just cleaning it. Maybe I was ham-fisted. Still another $300.

It takes up an entire bench, has no secondary use, and with water running and glass spinning, you’re babysitting it the whole time.

How I do it

My setup runs with Torr Kitchen equipment. It includes a loading vessel, condenser, recovery vessel, heat source, and vacuum pump. That’s the whole system.

There’s no chiller. The condenser is either ice-cooled (Torr-nado) or air-cooled (Torracane). No cold trap either, because it’s a closed system and the pump isn’t running during recovery. The ethanol has nowhere to go but the recovery vessel. Nothing running means no regulator, and there’s no spinning glass. Recovery runs around 90°F, so you keep the good stuff you worked to pull out.

Need more volume? I can feed it in-process from a bigger container, up to about 4 liters through the 1-liter setup, or swap in the 4-liter loading vessel in the same footprint. Filtration runs right on the same vessels. The pot also works as a hybrid pot, a vacuum chamber, and for vacuum infusion.

Before you buy one

Rotovaps have their place, like big batches and lab work. For small batches at home, “just get a rotovap” leaves out the chiller, the pump running the whole time, the cold trap, the regulator, all that glass, the space, and the fact that you’re really running about a liter.