Thanks, you're right about fluoroketone cooling, my example was bad. A case that does get it: in obsidiax-ice-foundry-mk2 four crafts of assembling-machine-1 (a crafting recipe without productivity) give 6 machines, and 5 in the regular ice foundry, since the machine's base productivity applies regardless of allow_productivity. If that's intended for all the categories the foundries take, all good. The heat exchanger reason makes sense.