The system I put together is designed for a batch size of 9L. Note that I define batch size as the amount of wort that goes in to the fermentor. The HLT (hot liquor tank), used only to heat water, is a cheap 10L stainless steel stock pot, the lauter tun is a 9L round cooler with a stainless steel vegetable steamer as a false bottom, and the boil pot / mash tun is a 15L graduated (yes!) stainless pot from Costco. To get a sense of scale, note the standard size racking cane and the shoebox.
The HLT is boring so let’s start with the lauter tun. It’s a miniature version of the 10 gallon round coolers commonly used for homebrewing. Most people have a suitable false bottom for such a small cooler hanging around their kitchen in the form of a vegetable steamer, so that’s a nice perk. The spigot and bulkhead that came on the cooler were quite unusual, and I spent a few hours and a few trips to home depot trying to botch together the existing bulkhead with a threaded nipple and ball valve, but I could never get it to seal completely. Eventually I just tossed everything except the fitted rubber washer on the inside of the cooler and bought a new bulkhead from the local homebrew shop.
I also soldered together a few pieces of copper tubing into an ‘H’ shaped sparge arm with a ball valve to regulate the flow of sparge water being siphoned from the HLT. The sparge arm assembly rests on top of the cooler, and small holes drilled in the bottom of the copper tubing allow water to precipitate. Check out the sweet sparging action!
The boil pot was a chance find at Costco, but it’s a really crucial part of the set-up because it’s exactly the right size. It will hold 13L of wort with a few inches to spare, which is the preboil volume needed for a 9L batch size, and it fits very nicely on the larger round of my electric stove. It even fits in the oven, so I can use it as a mash tun. Before I start heating the strike water, I preheat my oven to 65C. After doughing in, the pot can just sit in the oven for the extent of the saccharification rest. For mash out, I remove it and put it on the burner. Since the oven can hold temperature reasonably well, and the mash tun can be heated on the stove, step mashing would be a cinch.
I ferment single-stage in an 11.3L carboy. To maintain a steady fermentation temperature, I keep the carboy immersed in a water bath. During the summer this water bath can act as a cooler; you can see some ice packs in the picture below. I also wrap the top of carboy with a wet towel that wicks up water from below, and a fan blowing across the top of the carboy speeds up the evaporative cooling. All this seems to keep the water bath, and presumably the beer, about 5 degrees C lower than the ambient temperature, and mitigates any daily temperature swings as well. During the winter, or when using saison yeast, I use an aquarium heater to set the water bath temperature.
Another benefit of the 9L batch size is that pitching a single tube of fresh white labs liquid yeast, without making a starter, results in the perfect cell count for an OG between 1.050 and 1.060.
The compact fluorescent lightbulbs in my bathroom will eventually spoil the beer if it’s left exposed for long periods of time. To prevent this, I keep the flaps on the plastic container closed, and throw a few towels on top to seal the gaps (it ends up looking like a little house with towel roofing).
I think the system definitely met the goals I built it for: compactness and extract efficiency (consistently between 75% and 80%). The biggest compromise is the size of the lauter tun. This system is not capable of making a big beer. Given the extract efficiency numbers I’ve seen, the lauter tun will only hold enough grain to achieve an OG of about 1.060 for 9L batches. It’s possible to make high gravity beers, but only by using an iterated mash.