I have been doing all grain brewing with my current setup for a number of years. It includes a 5 gallon hot liquor (water essentially) tank made from a Igloo Cooler. I usually load it up with the sparge (used to flush the sugars from the mash grains after mashing) water when I am heating up the strike (initial water put into the mash to bring it up to the right temperature) water. I just let the water remaining from the strike amount continue to heat up until it’s about 178 F degrees. By the time the mash is done, the output of this tank is around 168 F – perfect for the sparge,
The issue I’d like to deal with is the actual Mash temperature. While the initial strike water temperature (BeerSmith tells you this plus quantity) can bring the mash to, say 152 F initially, but the time an hour has passed, the mash will be down to 148 F or lower, causing different enzymes to have an effect on the kind of sugar produced (more fermentables at the lower temperature). I can continue to add hot water to the mash to keep the temperature at 152 F, but it’s hit or miss.
I needed a recirculating mash system that would not only allow me to keep the temperature of the mash constant, but also allow me to do step mashes (multiple temperature steps that cause different enzymatic actions). There are basically two major methods for this: RIMS (Recirculating Infusion Mash System) and HERMS (Heat Exchanger Recirculating Mash System). The drawback of a RIMS system, with a heating element in direct contact with the recirculating wort is that some of the wort that passes over the heating element may experience temperatures higher than the desired temperature, although with a good flow past the heating element, this is minimized. Over time this can denature enzymes and add caramelization of a small amount of the wort. This can add up in a multi-step mash and affect the beer style you are trying to brew.
So I decided to go with a HERMS approach and have a Hot Liquor Tank (HLT) with a copper coil inside for the recirculating mash wort. The HLT water is set to the deserted step temperature (or slightly higher) such that the output temperature is brought to the desired mash step temperature.
In the picture below you can see the HLT connections:
Hot Liquor Tank Connections Detail
The top connector is the Wort In connection that goes to the top of the copper coil. The bottom connection in the front is the Wort Out from the bottom of the coil (so the wort in the coil will drain out when done). There is a T concoctor for adding a thermometer measuring the wort temperature going into the mash. The connector in the back on the bottom is the Strike/Sparge water out.
The heat exchange takes place when the wort flows through the copper coils as shown below:
Hot Liquor Tank Copper Coil Detail
You can see that the coil is suspended such that the surrounding water in the HLT will transfer it’s heat into the wort flowing through the coil. I plan to use my propane burner to bring the water to the strike temperature initially and then use an electric heating element (seen through the coils above) to maintain the temperature of the water in the HLT. I don’t plan to add 220V where I brew, so this is a 110V element. I plan to use a controller that senses the Wort Out temperature with a probe inline and turns on and off the heating element to maintain the set point temperature.
The below picture shows the electrical connection for the heating element:
Hot Liquor Tank Heating Element Detail
Lastly, I plan to use the same heat exchange principle to cool my wort after the boil by adding ice and tap water to the HLT and recirculating the finished wort through the coils yet again and whirlpooling in the brew kettle with the cooled wort until the entire wort is cooled to the yeast pitching temperature.
My new HLT was designed and built by a local (Boulder, CO) homebrew shop called Boulder Fermentation Supply. Check them out if you have something similar in mind,