Heating Options

One early decision that you have to make when choosing a brewhouse (and a site) is how you are going to heat the process. Heating is an essential step in brewing (mostly done in the kettle tank) as it is the one which typically makes the product safe to drink. The heat generated kills off any nasty bacteria etc. that has found its way into the product either via the raw materials or the water supply.

There are 3 common ways that breweries heat the process: Electric elements; direct/indirect fire gas; or steam jackets. Which one you choose has a big knock on effect to the overall cost of the project, the utilities required, the time needed to make the beer, the quality of the beer itself and a bunch of other more detailed factors.

As with most things in brewing there are multiple variations of these options but let’s look at each of the basic configurations and their pros and cons.

Electric Elements

This is pretty much as it sounds. Electric heating elements are usually inside the tank (very much like the kettle in your kitchen). The elements turn the electricity into heat and the heat is transferred to the liquid until you get to the temperature you desire.

The key advantage is that electric elements are the cheapest and easiest way to get operational. Elements are relatively cheap and you can add more of them to get enough power to boil within a reasonable timeframe. Most breweries use 3-phase elements and have 2 or 3 installed into the kettle. Most commercial sites have 3 phase available so it’s a simple job for an electrician to wire them up and then you’re up and running. Electric elements are also very easy to control so connecting them up to some form of automatic control is very simple. Another advantage is that they are less of a safety concern as there are no concerns about gas/carbon monoxide leaks or dangerous open flames.

However this comes at a price as there are a few disadvantages to electric heating. Firstly it takes quite some time to get to the boil point even with 3 or so elements. You can be waiting 60-90 minutes or even longer to get to the boil after you have transferred all the liquid into the tank (the lautering step). This adds a lot of extra time to the day and also creates a bottle neck if you want to brew more than once.  If you decide to add more elements to speed things up you might increase the demand on the electrical supply to the point that you need to upgrade it. 3 x 18kW elements draws a lot of current! Secondly, electric is expensive compared to gas so although the upfront cost is cheaper the running costs are considerably higher per brew. Another issue is that cleaning them is a real pain. As the heat source is concentrated to localised points at very high temperatures, well above boiling, they build up lots of burnt on proteins and sugars so at the end of the day you need to get in there to give them a real scrub. This leads on to what is probably the biggest disadvantage – reduced beer quality. This carbon build-up breaks away from the elements and into the beer. If you don’t do an excellent job cleaning the elements every time then you can end up with smoky or rubbery flavours in the finished beer.

Electric heating elements

Direct/Indirect Fire Gas

Indirect fire gas heating coil – Credit Pentrich Brewing Co.

A direct fire gas setup consists of a gas burner fit to the outside of the kettle. The burner blows a flame into a contained box fixed to the underside of the kettle to heat it. The indirect method is similar but instead blows the heat from the flame into a chamber within or around the tank. In the UK it is common to see an indirect gas configuration where the heat is blown into a coil tube which sits inside the kettle.

One major advantage of this solution is that it is much quicker than electric. You should be able to get to the boil as you are finishing the lautering step or at least a short time after. This reduces the time needed to make the wort on brew day. Another is that it’s cheaper to run on gas than electric. Finally there is a much higher surface to liquid ratio so the chance of scorching is lower, particularly so for the coil design (but still very much possible due to the high temperatures). This means better quality beer and less scrubbing (although you probably still have to get in to clean it fully).

Direct/indirect fire systems have higher up-front costs, both from an equipment cost and also installation. There are also safety issues – you are working with gas and fire so there are regulatory requirements that need to be met as well as regular maintenance to complete, all this further increases the price. Although they are quicker to get to the desired temperature than electric elements they are relatively energy inefficient which isn’t great for the environment. Therefore as you can probably guess they consume a good amount of gas, if you don’t have a big enough supply (or a gas supply at all) to the building then you may need to look at storing lots of bulk gas. Holding this on site brings yet further safety and security issues which also have to be addressed, again at a cost.

Steam Jackets

A steam jacket heating solution requires a chamber between the inside tank wall and the outside tank wall. Steam is pushed through this chamber (creating a “jacket”) which heats up the metal surface of the tank and this transfers the heat into the process. The steam is generated by using a gas boiler (or an electric boiler but this is not common) where water is fed through the heated section and becomes steam. This steam is pressurised and fed to the tank jackets. The steam condenses inside the jacket and leaves as hot water to be turned back into steam by the boiler. This state change from gas to liquid releases a large amount of heat energy into the process.

Steam jacket designs are very fast to reach the designed temperature. It has the biggest surface to liquid ratio so coupled with the high energy transfer into the process it heats the wort very quickly so you should have no trouble reaching the boil by the end of lautering if not before! They are also very energy efficient so coupled with running on gas they have lower running costs. From a quality standpoint, the pressurised steam is only a little higher than the 100°C needed to boil the wort therefore there is almost no chance of scorching resulting in the best beer quality. They are also very easy to clean with proper clean in place (CIP). No need to get in to clean these tanks!

Steam heating process example – Credit Watson McDaniel

As great as steam systems are they come with disadvantages. They are very expensive to buy and integrate into the system vs the above options, lots extra pipework and an expensive boiler. All this takes up loads of space and a lot of time to install and commission. Steam is also quite dangerous, the system is pressurised so there is a real safety hazard if it were to fail. We have all seen a steam pipe burst on TV/video games and none of us want to be anywhere near one when it does. Sadly steam leak incidents do happen and there are operators who have been severely injured and killed as a result. Due to these major safety concerns there are further regulatory controls, maintenance requirements you must comply with for steam on top of what you already have for just running gas. To further enforce this you can’t get insurance if you haven’t complied.

There are a few other rare options such as using an open flame under the tank like a giant pot on a stove. These other options are less common and for good reason. The very first system I brewed on was like this and it took about another 2 hours AFTER the transfer to get to the boil for only 300L!

So which one have I selected for the Azvex brewhouse?

None of the above.

As mentioned, these 3 solutions above are the most common but I have chosen to go for an uncommon approach – Thermal fluid.

Thermal fluid heating systems are very similar to steam jacket systems. Instead of pushing steam through the jacket you push a hot food grade fluid through the jacket to transfer the heat. Due to the similar design the upfront and installation costs are also similar.

Why would I go for something that is not common?

There are a few reasons. Steam solutions rely on a state change from gas to liquid to transfer the energy, to achieve boiling you need to pressurise the system which has safety implications as mentioned above. Thermal fluid on the other hand can be up to many hundreds of degrees at atmospheric pressure and remain liquid, therefore there is no requirement to pressure the system because we only need a little over 100°C for brewing. This removes a large amount of safety implications. If you get a leak it is a mere drip, not a jet spray like turning on a power hose if it were pressurised. Steam boilers are very efficient but when using a correctly specified thermal fluid the efficiency is even greater! I won’t bore anyone with the thermodynamics or fluid mechanics here but put simply the thermal fluid has better heat transfer properties than water/steam for this application leading to lower energy costs, lower CO2 emissions and faster heating times. Another great advantage over steam is it is very low maintenance. You fill the system up with the fluid and run it without much further interaction. Steam however is different, you need to treat the water regularly to remove solids otherwise you will have scale build-up leading in poor efficiency and premature failure, you also need to control the pH as the steam can become corrosive which will ultimately lead to a pipe failure. Losses in steam systems mean that top up water is also needed. Thermal fluid systems don’t have this issue.

Thermal fluid heating process example – Credit Pirobloc

This all sounds great doesn’t it? Well it is but there are of course down sides or a lot more people would be using it. Thermal fluid is actually fairly common in processing plants including food and beverage applications, just not in breweries. The main reason for this is that steam is incredibly usefully to a brewery. It is great for sanitising and cleaning. Keg and cask washers are a prime example. If you heat with steam then you have steam readily available on site for free which is a real bonus. Another disadvantage is availability when there is a failure. There are lots of spare boilers and parts available to get you back up and running on steam but they are less available for thermal fluid solutions. Mine was built to order.

In summary, there are lots of factors to consider when choosing how to heat your brewhouse, as with most things in brewing this ties in closely with budget, constraints and quality. Every project is different so there is no real right or wrong answer but for me the solution was to go with thermal fluid.

What’s the current status?

The brewhouse has completed manufacture and the factory acceptance test (FAT) so will be shipping imminently!

I also expect to get the keys to the site in the coming weeks (hopefully days!) which will mean the real work can start in preparation for the brewhouse arriving (more on this next time). In the meantime, here is a little look at the manufacturing progress.

The Azvex Brewhouse – Final stages of the build

Completed Azvex Fermenter Vessels (FVs)

It is getting closer and closer to the date of the first brew so to keep in the loop, signup using the relevant link below.

I told you this update would come much quicker, and so will the next one…

Adam Henderson – Azvex Brewing Co.