Chiller won’t stay cold under load

The chiller we have (ai) won’t hold its low temperature while using it with a re501 roto.

I set it to -10 c. It drops to that. I fire up the roto. And slowly the temp of the chiller raises and doesn’t drop back down.

We have a 1:1 poly ethylene glycol and distilled water mix in it.

I believe the chiller is fighting you hot oil and heating bath.

Indeed. But it should be stronger then a bucket of ice water. Which is how I finished
Trying to figure out why

How many liters is the cooler’s capacity?

I believe the manual said it moves 20l a min

Chiller model #?

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It came with the 10l spd kit from ai

Capacity of the reservoir? Cooling capacity in Kw?

I’m gonna guess your chiller is too small


It’s hard to see fro the pic

Seems @SIMSAM and @square_root_pharms got this covered.

If a manufacture - such as AI - gives you a “turn key setup”. Double the size and performance of the setup. Just my 2 cent. I only use AI C80 chillers for that specific reason.


It’s a 7L

Guess it’s only good for 2L Rotos according to their site


SPDs can use the tiniest weakest chillers because the SPD head only needs to be chilled to 25C-45C.

Rotos will quickly overwhelm a chiller if it not big enough.
You’re going to need a bigger chiller.



I still thinks it’s insane that a bucket of ice water has more cooling power then a $2500 chiller. Jesus lol


Build your own chiller using a 2 ton window AC unit


I’ve been using tap h20 the last 4x with my re501. I have a vrm circulating heater chiller that is a JOKE for chilling. It couldnt chill an eskimo in antartica.

Bought a leakphang type unit from my local spot to try out next rotovap run.

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Clean the chiller radiator with AC radiator cleaner from home depot. My chiller always does this, your radiator probably has dust on it and cant disappate heat

If you call AI ( which I did ) this is what theyll tell you to do

If it wont stay cold your chiller is over loaded and you need a bigger one