Decided to write an article about cooling wort with a CLT today, because it came up in a discussion on a “wash” project I’m working on. Wash is the base, from which you make spirits when distilling.
This is a little different for me, as not strictly a brewing project but similar enough. It was a modest expansion of the system to 1,000 litres so the client needed some form of cold-water tank, to chill the wort going to the fermentation vessel (FV).
So, we got into a discussion about having a CLT. The client and I debated the need for a dedicated CLT, it was an interesting talk which the client found useful. It made me realize, an article about cooling wort with a CLT might valuable so, decided to write this.
What is a CLT?
A CLT is short for cold liquor tank, it’s a dedicated vessel in your brewery used to chill and store water. The tank is usually stainless steel and placed near the brewhouse, preferably by the heat exchanger.
The tank is jacketed, meaning it has an inner and outer shell. Between these shells is a coil pipe which allows glycol from your cooling system to pass through it. Enabling you to chill the water in the tank to the desired temperature.
The temperature you chill the water to, is around 1°C to 7°C depending on the beer being brewed. The water in the CLT is pumped through a heat exchanger to cool the wort going to the FV.
As the cold water passes on one side of the heat exchanger, hot wort passes on the other, allowing the liquid to be flashed cooled. Meaning it’s instantly chilled to the desired temperature needed for fermentation.
The water doesn’t come into contact with the beer but, instead goes to a hot liquor tank (HLT). The cold water “takes” the heat away from the beer, becoming hot itself. This newly created hot water can be used for the next brew, or cleaning.
The Alternative to Having A CLT
When buying a brewhouse, many manufactures don’t offer a CLT. Instead, they have a two-stage heat exchanger (HX). A 2-stage HX, uses mains/city water for the first stage of cooling, which goes to the hot water tank.
It also uses glycol from the cellar cooling system too, to chill the wort. Hence two stage, using mains water and glycol. The advantage of this system is you’ve one less tank in your brewhouse.
If you’ve limited funds and/or don’t have much space, it can be the preferred option. However, as a consultant with many years brewing experience, I always advise my clients to have a CLT if possible. Let me tell you why…
Advantages of Cooling Wort with A CLT
Let’s take a look at some of the advantages below:
Have the Water at Desired Temperature All the Time
When using city/mains water for wort cooling, the water may vary in temperature throughout the year. In summer mains water can be 12-20°C higher than other times of the year.
For lagers (and even ales), it’ll be hard to get the wort to the desired temperature. Meaning your glycol works harder using a two-stage heat exchanger. Leading to the glycol temperature being much higher by the end of wort collection.
Furthermore, you might need to turn off the FV’s in your cellar, already on chill, otherwise they could heat up.
Please also note, the ambient temperature being higher too (it being summer), the whole glycol system has to work harder to bring the glycol temperature back down to normal operating levels.
You’re really putting a lot of pressure on your glycol system in the summer months, when it’s already working harder anyway, due to higher ambient temperatures.
Consistent Water Temperatures
Granted, this is less of an issue, but with water out the CLT, you know the temperature will be consistent through the whole collection of wort to FV. In some instances, the city water can fluctuate in temperature.
This can affect the overall temperature of the wort going to FV as result. Unless, you’re keep a constant check on the collection. Obviously, you keep an eye on the collection to the FV, but knowing your cold water is a constant temperature is reassuring.
You simply need to remember to recirculate the CLT before wort cooling so, there’s an even temperature throughout your tank.
More Hot Water Created for Cleaning or Further Brewing
When you use just cold water to chill the wort, you’re creating a lot of hot water which can be used in subsequent brews or for cleaning. For instance, I like to clean my kegs a day after a brew day.
As I know I’ll plenty of hot water for the job. Furthermore, if you decide to do a proper caustic brew the next day, then you also have plenty of hot water for the task.
Where using a single stage water tank comes into its own, is doing back-to-back brewing. Please note, the hot water created from the wort collection can be used to sparge of the next brew.
Less Work for Your Glycol System
Using a single stage cold water heat exchanger means you’re not using your glycol for cooling wort. Therefore, its less work for the glycol system, plus you don’t have to turn off cooling to cellar tanks already on chill.
Another advantage includes, a certain size glycol system is now capable of cooling more cellar tanks. So, more cellaring tanks can be added on installation or later when expanding.
Yes, you’re using the glycol to chill the water in the CLT but, that’s a slower process and takes 24 hours or so. It’s not overloading the glycol system, unlike using glycol to chill the wort.
Disadvantages of Cooling Wort with A CLT
As mentioned before, having a dedicated CLT is an extra cost with all the piping and controls, to plug the tank into your glycol system needing to be paid for too.
However, the initial outlay can pay for itself over time, with hot water you make, being used for other jobs. Heating water is expensive.
Also, if you’re doing back-to-back brewing, it nice to know each brew makes hot water for subsequent brews.
A CLT can take up a fair amount of space. So, if you’re a brewpub, where space is a premium, it might not represent the best option if it means you lose a table or two.
When you use a CLT, you need to fill and start cooling it, at least 24 hours before brew day. It takes time to bring down the temperature.
Furthermore, if haven’t got great water pressure, it can take time to fill a tank. Plus, you might not be able to use water elsewhere when you’re filling. Meaning, it’s another action you need to plan for in your schedule.
Starting the Round-Up
Ok we’ve spoken a lot about the advantages and disadvantages of having a CLT. As you can tell I’m for CLT, if space and budget allow. If you’re still unsure, and want to talk about them with me, then please email me at: firstname.lastname@example.org.
How Big Does Your CLT Need to Be?
Well, it depends on the size of your brewhouse and what beers you brew. If you’re brewing lager which ferments at colder temperatures than ales, you’ll need a bigger CLT.
Furthermore, if you do back-to-to-back brewing, having a larger CLT is recommended.
A decent heat exchanger will be able to utilize 1.3 liters of water for every 1 litter of wort to chill within 5.5°C (10°F) of water temperature, if the target temperature is 10°C (50°F).
Usually, manufacturers and brewing consultants recommend a CLT two times the size of the brew length. So, if you’ve a 1,000-litre brewhouse, having a CLT of 2,000 liters is recommended. As it allows you a buffer, and to chill wort for lagers easily as well.
However, if you’ve a brewhouse which does several turns (brews) a day, it advisable to have a CLT three times the size of brew length. It’ll need additional filling throughout the brew cycles if doing a several brew per 24 hours.
Cooling Wort with A CLT – Conclusions
If you’ve space and budget for a CLT. I would advise having one. It’ll pay for itself and make planning and your brew days easier. As you’ve a known volume of water at a set temperature.
Being able to use this cold water to make hot water is useful, especially when doing multiple brews, a day. The cherry on top is it means less work for your glycol system so, it’s not stressed when trying to chill hot wort.
If you’re looking at options for your brewing project and need some help with logistics to figure what setup is right for you, then feel free to email me at: email@example.com.
Who Am I?
My name is Neil and I’m a brewer with 25 years’ experience, I’ve worked on many different brewhouses over the years and done several installs. I now help people plan and source equipment their brewing projects.
Please feel free to read other articles on my site, with the starting a brewery category, the most useful for people researching for their own brewing project.
Furthermore, I was recently on the Build Me A Brewery Podcast, where I talk about equipment lists and sourcing, please feel free to listen to my episode below:
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I look forward to hearing about your project, and hopefully able assist you on making your vision a reality.
Have a great day,