Homebrew Beer Blog

The defining part of a HERMS is the wort flows through a copper coil. The system is simple, you put the coil in a hot water bath, and the the wort goes through the coil, warming the wort.

There are two typical options here, one is to use the hot liquor tank (HLT) and the other is to dedicated HERMS container. My experimental system used a cooler as a container and was electric. Since I wanted the heating power of gas, it made the most sense to use the HLT.

The advantage of using the HLT is your HERMS water is also your sparge water, ready to use at the end of mashing. The down side is you need to take greater care of what you put in there, because well, you're going to drink it! Reading the HLT stir motor post, that would be one example. Another disadvantage though is you need to generally use more water to cover the coil and you need to keep that water warm throughout the brew process, rather than say the last 30 minutes of the mash. Also, you need to have your HLT water heated before you dough in, if you want to use the HERMS from the start.

To mostly address this, I wanted to get a compact coil, so I wouldn't need much more wanter than I need for the sparge. It kind of works out that one one reason I need a HERMS is because I use a stainless MLT, but being a kettle, that lets me direct heat my strike water the same time I heat my HLT. So, two burners heating at once speeds things up, compared to heating everything in the HLT and transferring the strike water to the MLT.

My original experimental system used an old 3/8-inch 25-foot immersion chiller. This worked OK, except that the tubing was a bit narrow. Occasionally it would get plugged with grain when I doughed in. Somewhat ironically, it was worst when I used rice hulls. When I looked to upgrade my system, bigger ID tubing was at the top of my list.

As far as heat exchange, this can depend on what you're doing. If you're just maintaining temps, the temp differential is pretty close and you don't need a great exchange of heat. Also, depending on you system, you may not want to pump too quickly, so slower you go, less copper you will need.

The idea of convoluted tubing is it's twisted. This maximizes the fluid contact though the coil, as it swirls around as it travels. Fancy, expensive, overkill, but cool. I picked it up at MoreBeer, and it's a great little exchanger. They sell just the convoluted coil, or as a finished exchanger. Personally, just buying the exchanger is worth it. The stuff is expensive, so why mess with it, and also they solder on fittings, and piping to those fittings. After you get the fittings, it might cost you $20 or so for your time.

I went overboard but I figured what the heck. The coil had two things I was looking for... bigger ID and a very compact design. The fact it was super efficient was a plus too. This coil is 25 feet of 5/8 OD, which I assume is about 1/2 ID. I think the convoluted twists probably affect the ID, but it's certainly bigger than 3/8 OD. Since upgrading to it last summer, nothing has jammed up in it.

If I skipped the whole convoluted deal, I would just go with 25-feet of 1/2-inch tubing. I wouldn't recommend 3/8, unless you had it laying around.

To help justify the craziness of convoluted, in the summer I'll probably experiment with using it as pre-chiller for the mega immersion chiller. It would seem pretty easy to just yank out of the HLT and toss it in a bucket of ice.