Homebrew: Temperature control

Quick history lesson, the IPA (India Pale Ale) was a British invention. India was simply too hot to brew the kinds of beer we have in Europe, they also didn't have the technology to keep brew/store rooms cool enough and so it was imported instead. The British Raj first introduced European beer in 1716 however it was found that over the long journeys it would go off. In order to stop it spoiling, it had to have a higher alcohol content and they also added lots of hops which act as a preservative. This is later what lead to the invention of the IPA by Bow Brewery of London in 1787 and became popular among East India Company traders.

Temperature plays a big big part in all aspects of brewing. If you want consistent results and tasty beers you need to have a method to regulate it, even if that's as simple as having a good climate and keeping your fermenter indoors at a consistent room temp or controlling more precisely with a fridge and heat belt during the colder/warmer months, especially if you're brewing in a shed or garage.

How can temperature effect homebrew?

Pitching Temp

This is the temperature of the wort when you add your yeast. If you're doing all grain brewing this is especially important, since you'll have to bring the wort down from boiling very quickly. Warm sugary wort is an ideal place for bacteria to grow and you don't want contamination. The standard method is using a cooling coil that sits in your hot wort (hose connected on either side and you pump cold water through), but I find once I get the temperature to around 35c it tends to slow down and it's harder to bring it down further without wasting lots of water (especially if the ambient temp is quite high). I'll always collect all the run off water regardless, none of it goes to waste as I use it to clean my equipment, water the plants and wash the car etc. Some people use an additional coil on the hose feeding in, and sit it in a ice bucket to cool even more. Here's a brew day I did with a friend, we used his modified sparge kettle, you can see all the steam rising as we just start to pump water through the submerged coil.

There's alternative devices such as plate chillers which are very effective, but they all have pros and cons like everything else. Mostly they are more expensive and involve more cleaning. Finally there's the 'no chill' method. You can transfer the hot wort to a heat resistive, food grade, jerry can (these are super cheap), that's already been sanitised, then close the lid and let it cool naturally overnight. The downside to this is that you can end up with more DMS in your beer, causing off flavours, it's really only best with certain beer styles.

If you're doing extract kits temperature is not so important since you'll likely only boil a few litres of water and then top it off with cold to level the temperature anyway.

Either way, you don't want to throw the yeast in too high a temp for a couple of reasons; 1. It can kill the yeast if it's too hot and 2. Esters are produced by the yeast (off flavors) mostly in the first two days of fermentation, so you don't want it sitting hot and gradually coming down over time. It's best to start at the right temperature.

Fermentation Temp

During fermentation, sometimes esters are a good thing, sometimes bad, they can change the flavour of your beer for better or worse and it really depends on the style you're going for. Have you ever had a traditional Bavarian beer and noticed that a banana flavour? That's an ester produced by the yeast called iso-amyl acetate. There's a couple of factors that can contribute towards why it gets produced, but the main ones are usually yeast strain used and fermentation temperature.

Every yeast is different. As a general rule of thumb, the average ale yeast likes 18 - 20c.

If you go too low, you'll have whats called a stalled fermentation where your yeast drops out of suspension and flocculates on the bottom. If you go too high you'll stress the yeast and produce off flavours.

The chemical reaction of fermentation produces heat itself and this is another thing you need to consider. If you insulate to steady the temperature peaks and drops externally then the heat produced can build up too much and if it cannot dissipate fast enough, you'll need some way to cool it down. In the warmer months in England, especially with the recent heatwaves, this has been particularly more important and I've started fermenting in a fridge rather than just indoors.

Initially when we had the warm temperatures, I tried cooling with a fan, it worked to some degree but as we reached 30c it simply was not enough and my temps kept rising.

You might be asking why I didn't use the fridge right there, and I actually ended up doing just that. Although it's my kegerator so is pretty full with 2 corny kegs, which I have to take out. I'm currently on the market for a second fridge I can dedicate as a fermentation chamber.

Cold Crashing

This is the typical method to filter beer naturally. Once fermentation has finished, after dry hopping, you'll want to bring the temperature down as close to 0 as possible without freezing your beer, for around 24 - 48 hours. This allows all the yeast, proteins, hop matter, to drop to the bottom. If you're not adding hops you can get a pretty clear beer using this method, otherwise depending on how much hops you add you might end up with something reasonably clear or quite hazy. There's additional methods using finings, gelatin and other products to filter further if required although personally I'm not too fussed for that as long as it tastes good I don't mind a bit of haze.

I normally stick my fermenter straight into the fridge for 2 to 3 days, once everything has dropped to the bottom i'll transfer the beer to a keg from there, I also transfer through a mesh filter on the dip tube that also stops any big particles from coming across. The keg goes back in the fridge and hooks up to my tap, and will continue to filter if anything else still has to drop in the cold temps.

Storage

Finally, there's serving/storing temps. Again, dependant on beer style, I'll usually keep my beer around 7-11c in the fridge ready to dispense.

I carbonate my beer using CO2 however, sometimes I'll also bottle condition which means adding a tiny bit of sugar prior to bottling. If you do this, you'll need to store the bottles at room temperature, so around 18c for 2 weeks. This allows whatever yeast is in the beer to re-activate and convert the sugar into CO2 instead. If you don't get the temperature warm enough you'll end up with slightly sweeter flat beer!

Methods to regulate fermentation temperature

Basic / Room Temp

You can keep your fermenter in a room temp environment for 2 weeks no problem. While you can crank the heating in colder weather, this method will limit you from fermenting in warmer months or in a hotter climate.

Inkbird

The most common device/method is using an Inkbird, these are around ￡30 - ￡50 depending on if you get a wifi enabled one or not.

Basically you've got a temp controller, a probe (which you'll need to stick on the outside of the fermenter, so it may not be 100% accurate unless you offset by a few degrees, some people alternatively sit the probe in a jug of water alongside the fermenter), and two plug sockets, to plug in either your fridge or heatbelt. You can use the controller to set the ranges and the inkbird will control the plugs to keep your beer within this range. It's a device that just simply works and is used by the majority of brewers, even commercially.

RaspberryPi + 433mhz Remote Controlled Plug Sockets

I didn't want to spend on an inkbird when I already had the same thing homemade from years ago. I just needed to tweak it a little.

7 years ago I built my own home automation system with a RaspberryPi, some C++, python and php. Basically, I had a 433mhz radio transmitter and receiver plugged into the Pi, and used these to control those (radio) remote control plug sockets you can get. It's the old school way before everything became an IOT wifi enabled device.

The probe was normally just taped to the outside of my fermenter.

I originally built this to use for various devices, lights, blinds, and a heat mat for my pet corn snake Susan. Now repurposed as a makeshift Inkbird. The problem was that it was very outdated, still running on python 2, old OS, flaky wiring. It worked really well for the first 4 batches, but since I was moving it around all the time I think the wiring kept tripping or coming loose and it was more hassle than it was worth. In the end, rather than investing more time re-building it and rewriting the code - hard to find the time these days. I figured I'd look for an easier option.

iSpindel + Wifi Smart Plugs

I initially got the iSpindel as a gift, it's a waterproof capsule, with a battery powered IOT wifi device. It uses an accelerometer to measure the tilt at which it floats in your fermenter, and with a fancy calculation, can work out gravity readings. It's not claimed to be perfectly accurate, but it's a great way to see the live progress of your fermentation, and understand when it has finished, without wasting 100ml samples each time you check with a traditional hydrometer.

As it turns out, this device also measures temperature and will give you an accurate reading since it's sat floating inside the middle of your fermenter.

There's two alternatives, the tilt hydrometer around ￡150 which is pretty pricey. There's also the RAPT pill around ￡100, again quite a lot. Granted they both have well developed apps etc, but I just cant justify the costs of those as a small homebrew enthusiast.

The iSpindel on the other hand, sure it's more rough and ready but it does the same job and costs a fraction. Around ￡40.

The instructions come with information to configure the device using ubidots.com, although there's lots of services you can push your data to, I like this one because it's free and it has integration options. The free account lets you push every 15mins, any more and you'll find you'll go over your quota, but I've found 15mins is more than frequent enough.

Here's what my dashboard looks like:

Being able to check it remotely is great.

Then you'll want to setup 'events', I created 4; LowBrewTemp, LowBrewTempCleared, HighBrewTemp and HighBrewTempCleared.

In each 'event' you'll have something that looks like this:

You can set your respective temperatures here. It's easy to adjust these in the mobile UI too. The 'action' will look like the following, basically you'll want to trigger a webhook on IFTTT:

Finally, in IFTTT.com (If this then that) you are allowed 5 applets for free. You'll want to setup applets respective to the events you have within ubidots:

Each applet will look like this and will trigger the relevant smart plug to switch either on or off:

In this case I'm using smartLife wifi plug (that's to control my fridge), but I've also tested with a tplink/kasa smart plug (to control the heatbelt).

I've found this method to be really reliable, and efficient. In the hotter days we had, the fridge was only turning on once a day for around an hour. I was quite relaxed with my temperature ranges but you can easily use this to keep the temperature within a degree if you want more precise control. The great thing is the reading is coming from directly inside your fermenter so you know that it's accurate.

I did find that a wifi extender was needed with this setup. Once the ispindel is sat in 20 + litres of beer, inside a fridge and in my garage, the signal just wasn't getting through, and it's quite common with this device. Other than that it's been working great since. I can remotely monitor, change my temperature ranges, or disable/enable each of the controls all together.