I have a VWR 371 hotplate/stirrer that I bought used. I'm using it now to evaporate about 400mls of water from an enthogenic mixture of cacti spirit . When the heating element kicks in the stir bar slows to a crawl. Is this normal? It's easily about 10% of the rpm's when the element is on as it is when it is off. That seems kinda shitty to me. What if I was doing something that called for vigorous stirring during reflux, I'd be shit outta luck. I can cracnk the spin up and it'll damn near sling 400mls out of a 1000ml flask lol. But, I don't want it to stir that hardcore. Wtf, am I gonna have to buy another one?

 

SOunds like a power issue.  We've bought several that had some sort of wiring issue - something wasn't done right in the factory.   I'll ask hubby when he wakes up.

I'd suggest using a frybaby or mantle for heating and just use the stir plate for stirring.  They are fine for small scale tasks like warming but when you need serious heat they just aren't up to the task.

Salat

I already got over $200 in it. I'm not sure if a new power supply would be financially worthwhile. I would like to have a mantle, but I want to be able to stir while heating.

You guys answered my question, though. I guess it's a common problem. I would expect it with a cheap $100 brand new unit, but this is supposed to be an industrial grade unit. It gets hot as hell, it'll boil water on 5 and it goes up to 9 or 10, I believe. I have read several procedures that call for vigorous stirring during reflux. How do you do this with a mantle?