Pros & Cons: Chilling Wort In A Fermenter Vs A Brew Kettle


For me, brewing beer is always a pleasurable activity that I have to sandwich between other obligations in my life. Too often I’m halfway through my brew day or bottling day (yep still doing that!) when the wife is tapping her foot waiting for me to go to the in-laws’.

So, any way that I can reduce the time spent doing any brewing task and not adversely affect my final beer is something worth paying attention to.

So, is there any real advantage or disadvantage to chilling wort directly in a fermenting vessel over a brew kettle?

Chilling wort in a fermenter is a viable way to cool it before pitching & is used for a no chill brew day. Generally, it’s better to use a glass carboy for this process to avoid chemical leaching. This method doesn’t require the use of a wort chiller & it will take 12 to 24 hours to cool the wort.

Sometimes I get hair-brained ideas, so I have to do my research and check that I’m not way off base. Below is basically all my research and I’ve come across some interesting ideas.

Pros: Chilling wort in a Fermenter

  • saves water
  • saves a lot of time
  • less equipment needed
  • less storage space needed
  • less exposure to air while cooling

Cons: Chilling wort in a Fermenter

  • risk of chemical leaching
  • glass carboy may shatter
  • takes longer in glass than aluminium
  • produces cloudier beer

What is the ‘no chill’ method?

The ‘no chill’ method is basically what it says on the tin, not chilling your wort.

You simply transfer your hot wort into a sealed container, or container you will seal, and allow the wort to cool down naturally over time.

If you live in a region where the ambient temperature is around the ideal pitching level for your beer yeast, then you don’t have to do anything more than wait.

For other brewers, you may need to use additional cooling methods such as refrigeration or an ice bath. In some places, you may even have to warm the fermenter back up if it gets too cold.

Of course, there are ways to still use a wort chiller and use less water, and I go through all of these methods in my full article “Definitive Guide: Chilling Your Wort Without Wasting Water“.

Dangers of chilling wort in plastic fermenters

The biggest issue you need to be aware of is the possibility of chemicals leaching into your wort. Recently there has been growing acknowledgement that some plastics can transfer BPAs into liquids stored in them which can be harmful to your health.

This chemical isn’t present in all plastics but others can be. When you pour very hot liquid, such as wort, into fermenting vessels that weren’t designed for this task, chemical leaching is a real possibility.

Even when you have bought a food-grade plastic fermenter, you need to be mindful of using it in the manner that it was intended for. As cooling wort directly in a fermenter is perhaps not spoken of as widely as using conventional wort chillers, companies may not factor in this type of usage.

My advice is that it’s better to be safe than sorry, so don’t pour your hot wort directly into a plastic fermenter even if you are assured it’s food grade. I would, however, not be alarmed at using plastic containers for fermentation if they were designed for that purpose.

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Issues with chilling wort in glass carboys

Probably in the back of your mind you have been thinking about what would happen to your lovely glass carboy if you poured piping hot wort into it. It’ll explode, right? Well, maybe.

Thermal expansion

The thicker the glass the more likely it is to crack or shatter due to the phenomenon of thermal expansion.

What happens is that the glass on the inside in contact with the hot wort will expand at a different rate to the colder glass on the outside wall. If the difference is big enough, that’s bye-bye to your carboy and hello to a mop and bucket.

Thermal shock

However, most explosive reaction is known as temperature or thermal shock. It’s the sudden change in temperature which causes the issue. So if you can slowly warm up your carboy, it won’t shatter.

The best thing to do is to test it out with regular hot water so that you don’t waste any precious wort. I’ve done this several times over the last couple of months and so far I haven’t had any issues with my glass fermenting vessel.

Insulation

Another issue is that glass is a much better insulator than metal, so if you were to leave your wort in a brew kettle it’s going to cool down much faster than in a glass, or plastic, fermenter. However, it’s more exposed to the air in a brew kettle while it cools.

Benefits of cooling wort in a brew kettle

Many brewers successfully chill their wort in a brew kettle and have done for years with no issues.

Brew and pitch the same day

The main advantage is that by using a wort chiller in an efficient manner you can chill your wort to the correct pitching temperature in anywhere from five to thirty minutes.

This means that you can both brew and then pitch your wort on the very same afternoon, which is great if you only have a limited amount of time to brew.

Improves beer clarity

By rapidly reducing the temperature of your wort you can force all the unwanted particles in your wort to collect and fall out of suspension, thus producing a much clearer beer.

Cools faster

Another important consideration is the fact that metal is a much better conductor of heat and a poorer insulator, this means that your wort will cool faster in your brew kettle than in a glass or plastic fermenter.

Water Wastage

One of the main reasons that many avid brewers are turning away from chilling wort in a brew kettle is because they don’t want to waste water.

If you go down the wort chiller route you are likely to waste anywhere from 1 to 20 gallons of water per minute depending on your water flow rate. That’s a heck of a lot of water just to do what nature could do naturally in a few hours.

Can you use a wort chiller in a fermenter?

As with most questions in life, then answer is that it depends.

It’s purely a question of the size of your fermenter’s mouth or opening and the type of wort chiller you have. If you don’t know much about wort chillers already, then why not check out my in-depth article: The Best Immersion, Counterflow & Plate Wort Chillers.

You could definitely use any type of wort chiller in a fermentation vessel as long as it could fit inside, in the case of immersion chillers, or that you could pump wort in and out of it, for counterflow and plate chillers.

However, I have to be honest with you. If you have gone to all the trouble of racking your wort from the brew kettle into another container, using a counterflow or plate chiller afterwards seems like an additional step.

What I mean is that a counterflow or plate chiller is best used in tandem with a pump to push the hot wort through the internal heat exchange system. Once the wort is cool, you can use the same pumping system to pour all the wort into your fermenter.

Of course, you could use the pumping system to rack it into the fermenter, chill it to some degree during the transfer and then adjust the set up to continue chilling. Anything is possible.

So, if you weren’t going for a ‘no chill’ brew day, I would only consider using an immersion chiller to cool the wort down in a fermenter as you wouldn’t be adding work to your day.

Using a fermentation chamber to cool wort

A fermentation chamber is an insulated box, often a chest freezer, which you can regulate and keep at the ideal fermentation temperature. This is crucial if you live in a hot place like I do, especially during the summer.

Now, it sounds quite complex and fancy, but a fermentation chamber doesn’t have to be more than a beer cooler which is large enough to fit an average size fermenter. If you place ice packs in the right place, then you can keep the temperature in the perfect range.

However, when you have the space using a dedicated check freezer or fridge with a temperature control unit (I recommend this Inkbird model with built-in Wifi which you can check out on Amazon) is ideal.

Using a fridge or freezer to chill wort

Of course, brewing beer doesn’t need fancy equipment or even a lot more space than is found in the average kitchen. So, if your family is willing, you can use the fridge or even the freezer to cool your wort down without the need for a wort chiller.

However, there are some dangers to using a freezer or refrigerator to do this, especially a freezer. I’ve gone into a lot more detail as to why you may not want to put boiling hot wort straight into your freezer in this article here.

Fermenter maximum temperature capacity?

HDPE (plastic)

Maximum temperature of 248°F/120°C for short periods

PET (plastic)

Maximum temperature of 140°F/60°C for safe storage of liquids

Cooling wort overnight

I honestly think that when you can do this it’s the best method, but it’s not always possible.

Simply transfer your hot wort into a sanitized and sealed glass carboy and then put it in a cool room for around 12-24 hours. I have done this most of the winter and had no issues at all with bacterial infections.

If you want to find out more about cooling wort overnight, I’ve recorded my experience in my article: The Real Pros & Cons Of Leaving Your Wort To Cool Overnight.

How to avoid bacterial infections

When going down the no chill route, many people would think that the risk of bacterial infections in your wort would be higher than when you use a wort chiller. But if you prepare well then this won’t be an issue for you.

Just make sure you do these things:

  • make sure you clean and sanitize your brewing space
  • clean and sanitize the fermenter (despite the hot liquid)
  • seal the fermenter while cooling
  • clean the outside of the fermenter & lid before pitching
  • limit the exposure of the wort to the air while pitching.

Phil - BeerCreation

Hey, I'm Phil. I'm passionate about all things beer. I love making it, drinking it and best all, learning about it!

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