Counter-Flow Wort Chiller

Everyone has different opinions on the best way to chill the wort in the kettle. After I built the HERMIT, I decided that I would use a counter-flow chiller mostly to save time. Personally, I think that as long as you observe good sanitation practices, there is virtually no difference in a counter-flow vs. an immersion chiller as far as the beer is concerned. It is only a matter of time and effort. I have yet to suffer any sanitation problems using this type of chiller.

The design for most counter-flow chillers is the same. Wort flows into a copper tube that is jacketed with a larger tube (mine is a garden hose) in which cold water flows in the opposite direction.

The design for my chiller uses 30' of 3/8" copper tube. A feature that I have added is one to force turbulent flow of the cooling water. By forcing turbulent flow, the heat transfer is substantially better and will bring down the temperature of the wort closer to the temperature of the cooling water. I accomplished this by wrapping the outside of the copper coil with a fine copper wire (about 0.040" dia) over the entire length (except about 12" from each end). The wraps are a couple of inches apart and I soldered the wire to the tube every few feet to hold it in place. The flow of water across the wire causes the flow to be turbulent, resulting in better heat transfer.

The wrapped copper tube was then inserted into a length of 5/8" ID garden hose and coiled up and secured with some zip ties. I used a copper tee and two female threaded copper fittings sweated together to form the connections at each end.. The open end of the tee fit into the garden hose and was secured with a hose clamp. A compression fitting then slid over the copper tube and screwed into the female copper fitting. I had to drill out the compression fitting to allow the 3/8" copper tube to side completely through it. At the other side of the tee, I screwed in an adapter to attach a standard garden hose. As you can see, I also made use of a quick disconnect for the garden hose attachment. Both ends of the chiller were plumbed identically.

To use the chiller, I made a small stand to boost the chiller to the right height to align it with the outlet of the kettle. A small piece of plastic tube connects the kettle outlet to the chiller inlet. Both ends of the tube are secured with some plastic snappy-clips (available at St. Pats). I attach a 2' length of plastic hose on the other end which goes into the carboy. To monitor the wort exit temperature, I use a sanitized bi-metal thermometer probe inserted into a small hole drilled in the tube. The hole in the tube expands slightly as the probe is forced in which makes a seal. Now, the cool wort flows over the probe and I can see exactly what the exiting wort temperature is from the chiller. A garden hose that supplies the cooling water is connected to the fitting next to the wort outlet from the chiller, and another garden hose is connected near the wort inlet to carry the cooling water away. When running, the cooling water flows "counter" to the flow of the wort. I use a valve on the end of the hose supplying the cooling water to adjust the water flow to get the desired outflow temperature.

In the summer, Knoxville water often runs 85 F or more which means I have to "pre-chill" the water that is supplied to the chiller. I pre-chill by running the water through a copper coil submerged in an ice bath before it runs through the chiller. Even using 14 lbs of ice, the wort only gets down to about 78 F. The warm tap water makes short work of the ice, so the first part of the wort gets chilled to 70 F or so, and the last part goes in at 85 F and averages out to about 78 F. In these cases, I go ahead and pitch the yeast and put the carboy into the Fermentation Chiller and crank the air temp down to 55 F or so for several hours which brings the wort down to 68 F where it is supposed to be. By that time, the yeast is kicking and all is well. The rest of the year, the water temp drops back down to where it's supposed to be and I don't have to bother with pre-chilling.

After each use, I run tap water through the coil to flush it, then siphon Iodophor through it and cap the ends with the Iodophor still in it. I store it with the Iodophor in it until the next brew session. As long as no air gets in, no mold will grow. At the next brew session I drain out the old Iodophor and siphon new Iodophor into it and cap the ends about 15 minutes before I use it just to make sure it's sanitized. Then I drain it out, chill the wort, flush the chiller, fill with iodophor again, cap the ends, and store it away. After almost 3 years of brewing, this procedure has worked very well with no indication of a sanitation problem.