Matt,
You have already bought a new stirrer, but I thought I'd post anyway. I have used several types of hotplate/stirrers the ones we used in the lab were corning and could bring a 4L Erlenmeyer to a boil. We used them all day some days to ready agar for the autoclave, make solutions etc... they arent cheap and you can find them on ebay, but if I were to buy one for my home lab I would go with Cynmar. They also sell huge stirbars for considerably less than the brew stores (even B3).
Cheers,
HH


