With the reduction in temperature today, it seems natural to turn my thoughts to the chilling of wort. Of the people I’ve chatted to recently about it, immersion chillers just don’t seem to chill the wort that far. As their name might suggest, immersion chillers are those that are immersed into the wort. They are copper coils, through which cold water is pumped.
Counter-flow chillers seem to be much more efficient. These are normally made of a copper coil, inside a garden hose, and cold water is pumped through the hose, at the same time as hot wort is pumped through the coil in the other direction (and therefore the wort is coming up against increasingly cold water).
Described much better here, and further discussion on why chilling is important is found here. This does make me concerned at not chilling my beer thus far, and might explain some of the off flavours I’ve had…