Counter Flow Chiller and Inline Aerator
by Dan Schultz
Oxygen (O2) is a key component for healthy yeast growth during the initial stages
of fermentation. There are a number of methods to get O2 into the wort. Some people
shake the bejesus out of the fermenter, others use an aquarium pump to pump air
through an airstone. The most effective way is to use a direct source of O2 under
pressure to feed through an airstone into the wort. These systems are pretty
common among home brewers.
Similarly, there are many ways to cool the wort after the boil is complete. The faster you cool the wort, the more complete the formation of the cold break (proteins that precipitate during cooling). Some use an ice bath in their sink or bathtub where the hot kettle is placed. Others build or buy an immersion cooler (wound copper tubing) that they place into the wort and then run tap water through the coil to cool the wort.
The most efficient way to cool the wort is with a counterflow chiller CFC). These consist of a copper tube within a tube. The wort runs through the inner tube while the tap water runs in the opposite direction though the outer tube. The CFC save time and water. Add a pump to push the wort through and you can drain five gallons of wort in 5 minutes and have it at fermenting temps and ready to pitch the yeast.
Put the CFC, pump and aerator together and you've just shaved an hour off of your brew day. In all, the parts will run about $250 if you purchase them all. The CFC can be built from hardware/plumbing parts and the pump is optional. On the low end side, figure on under $50 for a home built CFC and aerator.
Here's one way to put everything together:
Counterflow Chiller: If you have the $100, go get a convoluted CFC from either St. Pat's or a Chillzilla from Sabco. Both of these units use an inner copper tube that's been twisted to significantly increase the surface area of the inner tube and highly increase the cooling efficiency. The difference between the two lies in the location of the ports (see photos above). Lower cost CFC's don't have a convoluted inner tube but work well nonetheless. If you're going to pump your hot wort, I recommend the high end CFC. For those on a budget, there's the Fearless Chiller or many others available at most homebrew (HB) stores.
Pump: A pump can be a very handy piece of equipment for home brewing. If you're going to use one for your CFC remember that it's easy to push the hot wort than pull it (boiling wort under a vacuum tends to generate pockets of gas that cause cavitation). Most HB stores carry pumps. Get one that handles 220°F easily.
Aeration Stone: Again, most HB stores carry these items. I like the ones that have 1/8" NPT threads on the open end. This will make it easier to attach it in the aerator block.
Aeration Block: I made my aeration block from a variety of copper and stainless steel fittings. They can also be purchased at St Pat's (the only place I've found them) for $27. Considering that the aeration stone costs $11.50 and the fittings will cost you at least $10, I'd buy the block next time. However, I had the stone and lots of extra fittings hanging around so I made one myself. I won't go through a materials list, the pictures show how do it pretty well, but it very easy.
O2 Source: A simple aquarium pump will suffice (approx. $15). You can use the O2 cannisters available at Home Depot and similar stores (you will need an inexpensive regulator), or you can use a welding grade O2 bottle with regulator. If you brew once a month, the welding setup will give you an ROI of about 18 months. A typical welding O2 bottle filled to 2200 psi will last for years.
Thermometer: While an inline thermometer is nice, it'll set you back another $35 or so. You can use your hand to feel when the exit temp is right. If it's cool to the touch, then you're right near 70°F.
When it's all put together, you have CFC/aerator that's works like the ones the pros use. Just start the tap water running, turn on the pump and then turn on the O2. I can pump down 10 gallons of boiling wort to 65°F (the Portland area has cold tap water all year round) in about 10 minutes.
Cleaning is a snap. Just run hot water with some PBW through everything and drain. Sanitize with Iodophor or other HB type sanitizers before each use.