hot fermentation temperature

Rick650

Hi

I just started brewing and for my second attempt tried a brewferm diablo kit. I left the fermentation bucket on the heater tray (the ambient room temp is around 16 degrees) and went to bed....

This morning I awoke and checked the beer which was around 32 degrees!! The airlock was bubbling like crazy! On the plus side the house had a lovely sweet beery smell throughout!

Two questions: 1) How did the beer reach this temp when the tray is supposed to only raise it 7 degrees above room temp?  it's a small (9litre) kit, would this effect the temp?

2) Is my beer ruined? 

I've read about off flavours being caused by the temperature being too high or the yeast dying in extreme heat. The beer has now cooled to 26 and is still bubbling away.

HBO_Staff

The good news is it sounds like you have nothing to worry about, the fact it is still fermenting shows the yeast is still doing it's thing and finishing the brew off, the warmer temperature may speed up the fermentation time though. The heater trays are designed for a 25 litre vessel and will raise the temperature by around 9 degrees above the ambient room temperature, but when the vessels are being used with less liquid, the heater tray wouldn't know this and it could get warmer like this. It is best to regularly monitor the temperature, one useful tip is to use the heater tray in conjunction with a timer so it is on only half or some of the time, some people set them so they are on only at night when it is often cooler. 

In some cases a higher or fluctuating brewing temperature can cause off flavours, but in practice keeping a brew a constant temperature is quite difficult for the home brewer doing this in their spare time, and usually you will not have any problems. We and many others have had brews too warm, then too cold, etc, but we have not had a problem with the flavour. The Brewferm is stronger tasting, and needs to be conditioned in bottles for a good few weeks for the full flavours to develop, the longer the better with darker/stronger beers. As it is still fermenting this is a good sign, and you're not the first to get the temperature this high, carry on as normal and try and keep it a bit lower like where it is now, and you should end up with a good brew, do keep us posted!

Rick650

Great, thanks for that, good news indeed! Newer thought of the timer, I'm currently going in and turning the heater on and off trying to keep a constant temperature. My wife was wondering what I was doing in the cupboard at 4 am. Not that i'm obsessed or anything.....

Rick650

Hi, a further question on this...

I had the beer fermenting which seemed to stop after 4 or 5 days, i left it and took a hydrometer reading after 7 days which was 1.022, I left it a further 3 days and the reading is still the same. This gives me a beer at about 4.9%, not the 'saturday night special' i was hoping for!

According to the instructions I should be getting a 1.010 reading.

I was thinking about putting it into a FV for secondary fermentation to see if I can get it any lower before bottling.

Any advice on this?

HBO_Staff

As a guide you need to aim for around 1.010, so it does need to go further before bottling. You can try a couple of things, firstly give it a stir around to try and get the yeast well mixed in and working, this will often make it finish off the last bit, make sure it is around the right temperature too. If after a few days that hasn't done the trick it may need another yeast adding, it's possible that the high temperature caused a problem, but what sometimes happens is that the fermentation slows down in the later stages, so give it a stir and a bit more time first