Introducing the RotoBooster

I made this little modification to the roto, just cut a gallon waterjug in half and cut a bottom the width of the roto condenser.
I have my roto set at 2.5L/hour comfortably and i put this little guy on and was able to get to 2.8L/hour.
Its only a 10% increase but i wonder how well it would work if there was a oring on the bottom to seal it so u can fill an insulated container with a dry ice slurry, i could go all the way up the condenser and beyond, so u could overfill and not have to come back to refill it often.
It wouldnt cost much to make and i bet it would increase condesation 25% if u had the whole thing covered in a dry ice slurry you could even have it clamped to the stand so theres no stress on the glass.


Dude. Just pump in super saline water cooled by dry ice. What temps you going that you need to chill the exterior of the condenser like that

-25C, what pump is rated to push dry ice temperature liquid?

I don’t think its about temps, it’s about having more surface area for your ethanol to condense on. I’ve noticed an increased recovery rate by pointing a strong fan at the exterior of the condenser on a 50L roto even with the chiller feeding the condensing coils working just fine.


I did that once just remember ro take it off, i woke up and got to the shop and the inner coil was shattered. It worked like a champ i dont know what i was thinking and leaving on overnight

been using a fishtank pump with dry ice and salt water seems to run just fine.


Sounds like ur liquid doesnt get that cold…
I think saline water bottoms out at -20C, i have my chiller set to -30C and still seeing an increase in recovery when i put the rotobooster on.

Oh shit… ill keep that noted, thanks!
You think the liquid inside the coils was heating them too much? I wonder what happens if u make sure the liquid is drained from the coils, or if that doesnt work, the liquid inisde the rotobooster could be drained.
Did u turn off the circulating cooler snd left the rotobooster on over night?

I shut the chiller off just like i always do, i wouldnt have thought i would have gotten or stayed that cold. It wasnt even as nice made as yours

The more colder surface area you have to condense in the better. I put my recovery flask in ice water but I’ll have to try an ice sleeve like this

You need a bigger chiller if a fan can help you increase recovery speeds by just being pointed at your roto. Surface area is important, especially on a little 5 liter. On a 20 liter though (or even a 50 liter) you have 4x the surface area. Are you using a 50 degree temp difference between your bath and chiller temp? ( meaning if your boiling off alcohol at 70 your chiller should be at 20c minimum) also, whats your vac level? Vacuum reduces boiling points requiring less energy to turn a liquid into vapor, you might need deeper vac which will allow your chiller to work easier


I have at least a 50 degree temp difference between my chiller and bath temps and pretty deep vacuum (using an oil filled vac pump with a cold trap), pointing a fan at the condenser glass still increases recovery speed because the exterior glass of the condensers isn’t cooled like the coils are, and they get pretty hot to the touch. Reducing the glass temp to even room temperature gives more surface area for gaseous ethanol to condense on.

If you don’t believe me, bring your bath temp up and chiller temp down with your roto at ambient pressure then add vacuum (be careful not to bump!) you will likely see ethanol condensing on the outside surface of your condenser while it’s still cool, once that glass comes up to temp you’ll only get condensation on the coils.

I don’t have that problem. My chiller keeps my glass cooler then room temp even under load. What temp are you running your bath and chiller at? Maybe youre using too much heat and vac, you need to find the sweet spot. It still sounds to me like your chiller is underpowered though. What size / model of chiller do you have?

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My “sweet spot” is “as fast as fucking possible” and I’m recovering hemp crude so I run hot on a team of 6x 50L rotos and don’t care about preserving terps. Bath temp 90C as much vac as my pump will get chillers set to -20C. Chillers are mostly Chinese shit that came with our 50L rotos but they maintain -5C when we’re running and ambient air temps are 15C or below. Chillers could definitely stand to be bigger but they keep up enough for what we’re trying to do, and long term I don’t really care about upgrading them as we’re moving away from rotovaps, can’t wait for my BZB unit to come in.

I don’t know what size your chiller & rotovap are but judging by the OP, having enough chiller capacity that your condenser exterior stays cold tells me either you aren’t evaporating anywhere near the capacity you could be or you are intentionally keeping your bath cooler in order to preserve terps as part of your SOP, I think the latter is a lot more prevalent on the weed side than the hemp side.


My vac is at 10 mbar (~8000 micron), bath temp at 45C and chiller stays at -22C. I use a doser pump to continously feed.
I definitly see an increase, i even used to put a 2L Cork Donut ontop and fill the inside gap with dry ice. I saw even that little bit helped.
The outside of walls of the condenser are cool to the touch without any additions and the intake and outake ports of the coil is frosted over everytime, so i think my chiller is good, its 3x the chilling btu compared to heating btus of the bath.
Idk about you but a 25% increase in rotovape time usually means i would get to distill a day earlier

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I have a 20 liter with an AI303020 chiller and recover around 25 liters of alcohol a hour. If youre pulling full vac you dont need 90c, thats wayyyyyy to hot at full vac. Youre using too much heat which makes your chiller work harder. Cfm doesnt matter after a cetain vacuum level, extra heat from the boiling flask isnt going to make your evaporation faster, itll only make your chiller work harder. Try running your bath at 70c, as long as your above the boiling poing of alcohol then you’re good. 90c is too hot at full vac.


Raise the bath temp to 70 and raise the temp of your chiller. The colder the chiller runs the less cooling power it has. At -22 youre maxing out your cooling capacities. At 70 c on the bath and like -10 on the bath youll have much more cooling power then at -22. At -22 youre fighting ambinent air temp which decreases cooling abilities. Heres the chart from chiller

As you can see at -22 my chiller only has 500 watts of cooling power, but at -4 it has 1000. Thats double the amount of cooling power. You have to use dry ice because you dont have enough cooling power. By raising your heat to 70c, youll be getting more cooling power because your chiller wont have to fight ambient air temps


This is exactly what i mean when i say dont break your glass trying to push extreme temperatures, it is a huge liability and not worth the risk


Yeah at -20C my cooling power is still over my heating btus. I basically got a cooler made for a 20L for my 5L. Why are u raising ur bath temp so high? I really dont like going over 50C, i usually like 40C or 30C if im doing acidic cannabinoid work.
I dont need to use dry ice. As stated above my chiller holds up just fine everythung is iced over on the outside ports. My chiller doesnt go above -20C, can keep up with anything i throw at it, so far ive only gone up to 60C on the bath temp

You need extra heat to push the vapor up the roto to the coil, kinda like when you distill. If there isnt enough energy then you wont get proper recovery. I recover hexane at 50c, i can literally boil it at room temp with just vac but its slow.