Fermenting too warm for part of fermentation

I brewed a porter the other day and it got off to a really quick start with fermentation (WL irish yeast). I went to bed, and woke up and it was kicking ass hard... the stick on thermometer said 80F but I'm sure it was even higher than that inside. I'd left it at room temp to let fermentation begin...

so anyway, I put it in my chiller and now its down at like 65 or so, but there was a good... oh, maybe 16-24 hours where it was too warm.

Was it long enough to cause the dreaded banana/off flavors? If so, how bad?

I recently tracked all my problems down to temperature, so I'm hoping I didn't mess this one up too.

Unfortunately, yes, it was warm enough for long enough to create off flavors. Most of the yeast-produced flavors happen within a few days of initial activity. All is not lost, and you did the right thing by recognizing it. Just RDWHAHB, and see what happens after a few weeks.

I just brewed a batch with WL Irish Ale and it got up to 78 in the first 24 hrs. I cooled it down to 72 and let it finish. The beer was really fruity when I kegged it, but after it aged it came out fine. Mine was an Irish Red, so your porter is darker and has a better chance of coming out alright. Let it age and I think you will be fine.

I have been experimenting with different fermenting temps with different kinds of yeast in different types of beer. Sometimes you get wonderful results by going over the recommended temps. It just depends on the type of beer and the desired tastes that you are trying to get.

doug, do you recall about how long it needed to age before it was okay? thanks

Here's a question along the same lines. If I'm supposed to keep my temp between, say, 60 and 73 degrees does it matter how much fluctuation there is within that range? My first batch stayed at a cozy 64 the entire time it was in primary and I set the bottles in the same location for conditioning so this won't be a problem with my first batch. My concern is that as the winter progresses the temp in the house will begin to fluctuate a good bit as we heat with a wood stove. Nice and comfortable when we go to bed but more than a little nippy first thing in the morning.

Mine aged for 4 weeks and was fine then and the taste did not change much over 3 weeks that it lasted.

Catnip1970,

As long as ferment temps stay withing the recommended temps you should be fine. It should not affect taste any if it drops or rises a few degrees. The problems will start if you let the temps drop below the recommended minimum temp. If your house temps drop to 50 at night, then it is very possible that you could get temps that are low enough to stall the yeast.

If I were you, I would do 1 of the following 2 things.

1. Use a heating pad. Put it under the carboy and turn it on low at night. Monitor the temps to make sure you do not get it too hot. You can use a dimmer switch wired to my heating pad. That way you can adjust the heat to the perfect setting so that the temps do not drop or rise over the night when it is colder in the house.

2. Put your carboy inside a slightly larger container(small plastic trash can works great) You can then use the water to buffer the temp change. Add some warm water every night before you go to bed. This will raise the water temp slightly but the wort temp will take time to heat up and by that time the cold room will have dropped the temp of the water.

Either way, you have a balancing act to keep up.............Personally, I use a Johnson Controls thermostat that controls a small heater inside of my fermenting freezer that is in my unheated garage. The heater keeps the temps inside the freezer chest from dropping below 65 degrees in the winter. It cuts on when temps go below 65 and cuts off when temps get up to 67. The freezer compressor is controlled also and cuts on when temps get hotter than 70 and cuts off when temps get down to 68. I leave a 1 degree gap between the heat and cold settings so that the heater and freezer do not fight each other. Temps stay between 65-70 degrees for brewing my Ales. I can change the temp range for lagering or set temps a little higher for ale yeasts that like 70-75 temps. You just need seperate heat and cooling thermostats or a dual (auto) mode house thermostat. The cost is about the same either way.

I just love having precise control over my fermentation temps all the time. I got tired of fighting the battle to try to keep a precise temp in different times of the year when I was brewing in my wood heated house. Precise control over the temps is critical when you want to produce a consistant tasting beer.

Thanks for that info. I usually get up at 3 am for work and cold wood floors on bare feet make it feel a little cooler than it really is. My beer ferments on the ground floor which stays a little warmer than the upstairs bedrooms. So far it's only gotten really cold a couple of nights but I'll have to start keeping a closer eye on it as the year progresses and will have to ferment in the basement when summer hits. I'll be tearing up one of my wifes heating pads soon...wish me luck.

Just wrapping your fermenter in an old quilt will help smooth out the temperature swings. Wait until the first 48 hours of the ferment are over or you might over-heat it.