Fermentation Questions (Smell & Temperature)

[Tactical Salad]

Hey all, I have some questions regarding the fermentation process. I recently bought a starter kit with two 30liter buckets, along with a very easy kit from BrewFerm. The 12 liters of what will hopefully become a good English IPA are now sitting in the corner of my room, but a yeasty/sour smell has started to develop around the bucket. So, 2 questions:

If it's smelling does that mean the bucket is not hermetically sealed? and is that a very bad thing?

Furthermore, BrewFerm's instruction manual says the fermentation should take place between 18 and 23°C. In my room it's around 23-23.5, but constantly that. I could alternatively put it in the cellar where temperatures will be around 18°C. So which is worse: fermenting at a slightly too cool temperature or a slightly too warm temperature?

Thanks and I'm looking forward to my time home brewing and on these forums

 

[mongoose33]

It's not uncommon for the smells of fermentation to be a little offputting. If you have an airlock on the bucket at least some of the odor will escape that way. It's also possible the bucket isn't sealed.

The issue with fermentation temp is this: yeast is exothermic, meaning it produces heat while active. It can raise the temp of the fermenting wort about 3-6 degrees C (5-10 degrees F) above the ambient temp.

So, you may think you're fermenting at 23.5, but it's more likely at 25 or 26 or 27. Or as high as almost 30.

When yeast ferments above its recommended range it will tend to put out off-flavors that you don't intend in your beer. If you have a choice between fermenting a little cool or a little warm, choose the cool.

[The exception to this are yeasts and styles that are intended to be fermented warm because the "off flavors" are actually part of the style. Things like Saisons, Farmhouse Ales, and like that. Also--there's a type of yeast called Kviek that does well at much warmer temps, which is useful if you can't get the temp down.]

There's an easy way to get the temp of your beer down below your ambient temperature. Take a wide, shallow pan that the fermenter will fit in, add a couple inches of water, then drape a t-shirt over the fermenter so it dangles in the water. The shirt will wick up the water, and when it evaporates, it'll cool the fermenter, perhaps as much as 5 degrees.

These kinds of things are called swamp coolers. Sometimes people will add frozen water bottles to the water in the pan to help keep temps down. Here's a pic showing one of these using a different type of fermenter, but the point is the same:

 

[Gnomebrewer]

As mongoose said, fermentation is exothermic.
Do the bulk of your ferment in the 18C cellar (which means the actual temperature of the fermenting beer is in about the 20C area) then once the krausen drops (typically four or five days) move it to the warmer room to finish.
Also, many of those kits have low quality yeast that has often been mishandled (I'm not familiar with Brewferm brand, so it might be different) - one of the best things you can do to improve them is throw the yeast away and replace it with a better yeast. The kit yeast will ferment the beer, but you'll probably find an improvement by using something like safale US-05.

 

[Tactical Salad]

Thanks @mongoose33 for all the information!

@Gnomebrewer thank you! What's the krausen, though? Hmm I'm not all too familiar with the different yeasts but from what I've heard Brewferm is pretty good, but hey guess I'll have to see what the beer tastes like in a couple weeks...

 

[mongoose33]

Thanks @mongoose33 for all the information!

@Gnomebrewer thank you! What's the krausen, though? Hmm I'm not all too familiar with the different yeasts but from what I've heard Brewferm is pretty good, but hey guess I'll have to see what the beer tastes like in a couple weeks...

Krausen is the foamy stuff on top of fermenting beer, such as in the pic below. When the beer is almost done fermenting the krausen will fall, and at the end, there will be very little of anything on top of the beer.