Ask Wine Wizard

How can I keep my fermenters cool during hot weather?



Dear Wine Wizard,

I desperately need to know how to cool my primary. I use two 50-gallon barrels to ferment my wine and am tired of using frozen one-gallon plastic jugs. There has to be a better way.

Vince Richter
Winnipeg, Canada

Wine Wizard replies: At my winery, I sometimes ferment grapes in the large, plastic bins they were picked in and I have similar cooling issues to the ones you’ve described above. Cooling your wine is important if your fermentation is getting out of control. Otherwise, the fermentation may give off hydrogen sulfide (indicated by a rotten-egg smell). In addition, the vigorous ferment can blow off the primary fruit aromas and have other deleterious effects on your wine.

The way you’ve cooled your primary in the past — by freezing gallon jugs full of water — is actually one of the cheapest, easiest and fastest ways around. Many winemakers I know are still fans of this technique.

For those readers out there that have never done the “ice cube shuffle,” cooling your must with plastic jugs goes something like this: Obtain some 1-gallon plastic jugs or other similar containers. They must be able to be sealed tightly. Fill them with water and put as many of them as you can in the freezer. Once frozen, make sure they are sealed tightly and dump them into your primary container. Depending upon how much cooling power you need, and how large your fermenter is, the number you need may change. A 50-gallon trash can that’s gently simmering might need a single gallon jug while a 200-gallon batch that’s peaking at 8° Brix and 90° F might take six. Punch down the fermenter, mixing thoroughly until the desired temperature is reached. While doing this, put more jugs in the freezer as you’ll probably have to pitch in some new ones eight hours later.

Needless to say, this technique is labor-intensive. If you don’t have a freezer, or just want to try something a little more automatic, you might want to try to concoct yourself a homemade cooling coil. A cooling coil is essentially a stainless-steel coil; you can place it in your fermenter and run cold water through it to cool the juice or must. I first had the pleasure of using one of these coils when I was working at a little winery up in the Santa Cruz Mountains of California and I have never been without one since.

The first step is to make a coil out of one-inch or 1.5-inch stainless steel tubing. This is where the metalworking comes in . . . you need a heat source to be able to bend the tubing. The cooler I have stands about three feet high, with coils that are about eight inches in diameter and about four inches apart vertically. I can lift this coil in and out of anything from a 50-gallon trash can to a large fermenter. You need to weld on standard garden hose fittings or, if you want hot water, you might want quick-connects for a water heater.

Many homebrew stores sell wort chillers, copper coils used for cooling unfermented beer (wort) after it has been boiled. Winemakers should avoid these as you should not allow copper to touch your wine. The pH of wine is much lower than that of wort and copper will leach into your wine.

Once you can hook the loop up to a water source and turn the water on slowly, you have a constant source of cool, warm or hot water travelling through the tube and cooling or heating your juice or must — sort of like a tank-cooling jacket but on the inside! Try to recycle the water by having the outlet end of the tube go out to your garden, yard or vineyard. Sanitize this device (or the frozen gallon jugs) just like you would anything else in your winery.

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