Heating and cooling

I’ve build myself a nice fermentation chamber with the help of this wonderful project. The first fermentation test is running, but I’ve got some questions.

Right now my beer temp is pulsating quite nice around the set temperature, looks good to me. But what I find odd, is that there is a constant heating, followed by a cooling going on. Is there a way to avoid this beheaviour? Or is this the normal way of keeping the beer temp constant?

I’m using a big old box freezer (hatch on the top type thing) and a small heating fan.

Any hints or help are more than welcome… Thanks!

That all looks pretty normal to me.


The frequency of the freezer temp oscillations doesn’t look abnormal, but their amplitude seems extreme. During the heating cycles your chamber temp makes a very rapid climb up to about 31C / 88F, and falls nearly as quickly, though in most cases this appears to be caused by active cooling.

Is it possible that your chamber temp sensor is positioned too close to the heating fan? I could see that explaining such behavior.

I’ve not personally experienced chamber temp swings like that. My current beer temp is 70F and the freezer’s recent positive peaks are about 72F, the recent negative peaks about 68F. I do have about 16 gallons in there so the thermal inertia may be higher than your setup, and my freezer is pretty new so its R-value is hopefully good too.

1 Like

It looks like you have one of those 1000W room heaters or the heater is very close to your sensor. What is the power of your heater?

I know they have been recommending those cheap lasko space heaters on homebrewtalk, but heating a tiny fridge with a 1500W heater is a terrible idea. I wouldn’t want to sleep next to it. Just get a reptile or greenhouse heater of 50-100W.

1 Like

Yep, I guess that’s the problem, I tried putting it on lower heat… but I guess I’ll settle with a lower power heating solution. Thanks for the quick reply guys!