Cheap fermentation temperature control

Fermentation temperature matters more than almost any ingredient choice. Ale yeast at 24 degrees throws fusel alcohols and banana esters; the same yeast at 18 degrees gives a clean beer.

A second-hand chest fridge, a two-stage controller and a seedling heat mat for winter. The probe is taped to the fermenter wall under a piece of foam, not left hanging in the air.

With a half-degree differential and a five-minute compressor delay the beer stays within half a degree of the set point, even on the most active day. Total cost was less than a sack of specialty malt.