Brewer’s and the craft brewing community in general enjoys the amount of control they can have over their system to provide the best beer possible. Controlling the key variables in a brewery is what creates successful beer. Therefore controlling the source of heat is a substantial manipulation a brewer can have in the process. Each source of heat has its pros and cons, and can be weighed accordingly to each specific circumstance. The heat source for a brewing system can be direct fire, indirect fire, electrical heating elements, and steam jacketed heating. Not one single heat source is dominant and selection comes down to the preference and pre-requisites of the brewery whether it is home or production size.
The first type of heating option is direct firing of the brew kettle or hot liquor tank. This means that a direct flame would be heating the vessel, and is more customary to home brewers. But they are as well found in systems up to 10 barrels where the direct flame would be heating the exterior of the tank. The findings are similar between the home brewer and the larger system in terms of benefits, which are a more vigorous boil, quicker time reaching boil, has the lowest startup costs, and most brewers have previous knowledge working with gas fired kettles. As far as the disadvantages go for direct firing caramelization of the brew kettle tends to happen more because of a single contact point of heat. So cleaning the caramelized wort is extensive, but some brewers prefer the caramelization in terms of flavor and recipes. Also the single contact point can bring up issues of scorching the wort as well. Another drawback of this heating option is that the cheaper upfront startup cost is balanced by the long term cost of inefficiency in terms of energy transfer from the direct flame to the actual liquid is 25 – 50%. This in term means more propane or natural gas to compensate for the loss of energy. This is the reason direct fire is not found in sizes above 10 barrels due to inefficiency.
The second heating method that also utilizes fire is the indirect use of fire to heat the brew kettle by either means of a heated jacket that covers the tank or by way of directing the heat from the open flame to a diffuser plate that heats a secondary unit that heats the tank. The advantages are comparable to the direct fire with low startup costs, quick boil times, and boil vigor. But the drawbacks are similar to the direct fire mainly being energy efficiency is low in this heating system and has a long term cost associated with it. The fire heating both direct and indirect remain consistent in that they are only relevant up to the 10 barrel size due to the fact that they are not efficient and brewing large batches means efficiency needs to be at an all-time high to drive down cost.
The third heating option for the brew house and hot liquor tank is electrical heating elements that are mounted on the inside of the tank where the elements are in direct contact with the liquid. Electrical heating is energy efficient because 100% of the energy being created by the heating elements is being transferred to the liquid. The advantages of an electric heating element is the control of temperature is much more precise, energy utilization is high, and no concerns about explosive or flammable gases. Some problems with the electric heating is cost of operation is higher than gas, needs a sufficient/safe source of power (not a typical household outlet or breaker), and heating elements must also be cleaned to ensure they are not giving off bad flavors. This style of heating is preferred on the 2 – 10 barrel size because beyond those sizes the electrical heating will take longer to heat up and be ready to maintain a boil, which means a longer brew day and precious time wasted.
The last option for consideration when heating a brew kettle or hot liquor tank is the use of steam that is created by an external device called a boiler. Steam from the boiler is then pumped into an insulated jacketed area of the tank to heat it. The advantages to a steam heated system are the rate of heat transfer is high, energy utilization is more predictable than gas, and cleaning is much easier compared to the other methods. Some of the disadvantages is the upfront cost of the external boiler unit, boiler inspection costs by state or municipal inspectors, boiler maintenance costs, and is not cost effective at small scale. Around the 12 barrel mark is when steam heating becomes the only option because other heating options are not viable in terms of getting a vigorous boil and maintaining it with such a large volume of liquid.