Build A Counterflow Chiller with Thermometer

Wort chillers provide several advantages, including reducing haze by precipitating cold break proteins, saving time, pitching yeast into proper wort temperature for better fermentation, and reducing the chances of infection.

There are two common types of wort chillers among homebrewers — immersion and counterflow. I chose tubular counterflow design for the speed at which it can chill large volumes of wort, ease of cleanup, simple design, and ease of construction. Counterflow chillers work by passing a cooling fluid (water in our case) in one direction over a tube of wort flowing in the opposite direction. This requires two concentric tubes, where the water flows in the outer tube, and the wort flows in the inner tube. Factors that affect the efficiency of these types of heat exchangers are the thermal conductivity of the inner tube material, surface area of the tube (diameter x length), wort and coolant flow rate, surface texture/shape, and the temperature difference between the cooling fluid and the wort. For our application, the most significant of these factors is the temperature difference between the water and the wort, known as ΔT. The cooler your tap water is, the greater the ΔT and the more efficient your chiller will be. The material most commonly chosen for the inner tube is copper for its flexibility and high conductivity. The length of copper tube you need will depend on its diameter and the temperature of your tap water. Copper can also be used for the outer jacket material, as can silicone and rubber garden hose. I used rubber hose for this build for the sake of simplicity and economy.

This project outlines an easy-to-use basic counterflow chiller designed for gravity flow wort. Using 3⁄8-inch copper refrigerator tubing, 25 feet (7.6 m) should work well with water temperatures up to 65 °F (18 °C). I added an extension on the end of my chiller to accommodate a thermometer to monitor the output wort temperature in real time. Knowing this, I can make adjustments to the flow rate of the cooling water and wort in order to achieve the desired temperature. A ball valve on your kettle is the easiest way to control the flow rate of your wort, but any in-line valve can be used. Sanitizing the chiller is as easy as siphoning some boiling water or sanitizer through the chiller prior to the end of the boil. Flush the chiller with hot water in reverse direction from normal flow (also known as “backflush”) to clean it after each use. A periodic cleaning with alkaline cleaner is recommended.

MATERIALS
25 ft. (7.6 m) of 3⁄8-inch copper refrigeration tubing (1⁄4-inch ID)
(4) 1⁄2-inch ID x 3⁄8-inch ID copper reducers. (Often labeled as 1⁄2-inch x 1⁄4-inch reducers)
~2 ft. (0.6 m) of 1⁄2-inch copper pipe
25 ft. (7.6 m) 5⁄8-inch high-temp
rubber garden hose.
(3) 1⁄2-inch copper tees
Rubber stopper size #00
Probe thermometer
Stainless hose clamps
Zip ties

TOOLS
Pipe cutter
Drill
Soldering kit (propane torch, flux,
lead-free solder)
Sand paper or wire brush
Bench vise or clamp