2011-03-09: I have posted a follow-up to this post, with my thoughts about the fermentation chamber now I’ve been using it for 6 months. The post is called “The Fermentation Chamber (revisited)“.
So, the brew has been boiled, cooled, racked into a fermentation vessel (FV), and the yeast pitched. Now what?
Ideally ale should be fermented between around 18 and 24C. In most rooms in the house this is a bit hit and miss, what with central heating in the winter, and the weather in the summer. My first solution was to stand the FV in a container of water, into which I put an aquarium heater set to 21C. Since the FV was standing in the water, the two bodies of fluid would remain roughly in thermal equilibrium, with the heater adding some warmth when required.
This was fine through the winter, but doesn’t help cool everything down when the outside temperatures are into the high 20s.
My current solution shown on the right. It’s a fridge, kindly donated by a colleague (thanks, Nicholas!), with a sturdy wooden shelf at the bottom to take the weight of 25 litres of wort.
The picture shows the Exmoor Gold conditioning in its barrel, and above it on a normal fridge shelf is my 10 litre batch of Riggwelter. I figured that you can comfortably fit more than 20 bottles of beer on a fridge shelf without worrying about weight, so I’d be ok with 10 litres and no glass bottles!
The temperature in the chamber is controlled by a clever little box – the ATC-800+ temperature controller, which I bought from a company called Forttex. The box can be supplied in 3 different packages: on its own; with a mounting enclosure; or fully boxed and wired. The former two options require that you to wire it up yourself. Fortunately I have a little familiarity with electrons (they’re small things the size, shape and colour of a small pea, aren’t they?) so I chose the package that just came with the enclosure. It’s simple enough to wire up, so I ended up sticking on a plug for power, and two sockets for the cooling and heating circuits. The box needed a few holes drilling for the cables, but it was all done in 30 minutes or so.
The way it all works is that a small temperature probe, on the end of the thin grey cable, is put into the fridge. The first brew I did I stuck it on the wall of the fridge, and for subsequent ones I stuck it to the side of the FV – which gives a slightly more accurate reading on the fermentation temperature. Probably a degree or so on the cool side still, but consistently close enough for the job.
You set the box for the temperature you wish to maintain, 20C in this case, plus the margin you want to allow, 1C for my set up. The box then switches on the cooling circuit (into which I plugged the mains lead from the fridge) when the sensor reads over 21C, and the heating circuit (into which is plugged the bulb you can see at the bottom of the fridge – soon to be replaced by a tube heater) when the sensor reads below 19C. The temperature is therefore maintained between 19C and 21C for the duration of the fermentation.
The fact that the FV is enclosed in its own box also minimises risks of infections or nosy insects (or cats!) getting too close to your precious brew.
The fact that I chose to put a plug and sockets on the box, rather than hardwire it in (which was an option), means that I can just unplug it from the fridge for a while and use it as a thermometer that I can leave in the middle of my mash (for example) to keep an eye on the temperature for the entire time.
2010-09-03: I ended up using a tube heater rather than a lightbulb to heat the chamber. There’s a blog post about the tube heater here. I also use the ATC-800+ as a temperature controller for the boiler when I’m using it as a Hot Liquor Tank during the mash.
