Most of us cool our wort using a chiller that relies on water as the working fluid. Tap water goes in one end, heat is transferred through a metal wall from the wort to the water, and hot water comes out the other side. Whether you use a coiled immersion chiller, a plate chiller, or a counterflow chiller, the heat transfer principles are the same.
These devices work beautifully in the winter, when tap water can run as low as 40–50°F (4–10°C) in some locations. But in summer, tap water is often warmer than your desired pitching temperature. How can you cool your wort to 65°F (18°C) with tap water that may be considerably warmer?
Enter the humble pond pump. Available at garden centers and home improvement stores for less than $20, a garden pump might become your best friend in the summer. Submerged in a cooler of ice water, a pond pump can deliver much colder cooling water than your household spigots.
Here’s how I use mine.
I connect one end of a coil of garden hose to the pond pump and place the pump in a large picnic cooler (there are rubber suction feet to keep the pump in place).
About fifteen minutes before the end of the boil, when I dunk the immersion chiller in my boiling wort, I fill the cooler almost completely full of tap water, straight from the garden hose.
To the cooler, I then add as many ice cubes and frozen gel packs as I have.
When the boil is finished, I first connect the immersion chiller to my household water supply and cool the wort as far as that will take me, usually the mid 70s Fahrenheit (upper teens Celsius).
I then hook the immersion chiller up to the other end of the hose attached to the pond pump, turn on the pump, and let it take the wort the rest of the way.
A pond pump is an inexpensive and, I would argue, indispensable tool for making great beer in summer. It frees you from the limitations of warm tap water and lets you hit pitching temperatures much more quickly than leaving a carboy or bucket of warm wort in a refrigerator and waiting for it to cool off.
Give it a try. You’ll be pumped.
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