What happens if you ferment too warm?

So I've always managed to get my FG down around or below 1.01.. The last 4 batches I've made I have not had a FG lower than 1.018..
Examples: Brew day 7/01/06 kept in the primary till yesterday 7/25/06
Batch #1 - OG 1.051 - FG 1.018 (Yeast Wyeast-1056)
Batch #2 - OG 1.060 - Current Gravity 1.030 (Yeast Wyeast-1272)

The temp when I started the fermentation was around 72F.. Just about the top that is recommended for both... After that we have had many days in the upper 80's and into the 90's... The temp in the basement has climbed to about 75 now... This is over the recommended fermentation temp for both yeasts. Is this the cause of this??

This is the first time I have brewed in the summer..

Thanks!

I would think not--if anything, marginally high temps would be likely to produce a faster fermentation, not a slow or stuck fermentation.

What else has changed? If extract, are you using a different brand of LME or DME? If AG, have you changed something about the mash procedure (Time, temp, technique, equipment?). Since you've experienced sluggish attenuation with more than one yeast sample, I guess that's not it.

Doing AG... Can't think of anything that has changed... I did use some yeast I harvested on these 2 batches... But the last batch that I used the new yeast on finished at 1.018 as well... (that one started at 1.046) But that one was back when it was right around 72-73ish...

My other batches were fermented at about 70F and had great results.... That is why I am baffled... I don't think they are really stuck... Just really slow.. I still have some activity.. Just very little..

I have noticed that at higher temperatures the initial fermentation is faster, but it can take a long time for it to finish. My Old Dog Brown went from 1.052 to 1.018 in 18 hours and hit 81F, but took almost two weeks to get to 1.012. Using the same yeast, but keeping the temperature around 70F, the Bent Rod Rye went from 1.046 to 1.008 in three days. I suspect the rapid change in ABV prevents the most of the yeast from adjusting so things slow way down, but I haven't seen any studies on it.

Basically you're going to get some extra fruity esters in the beer and the possibility of higher 'fusel alcohols'.

G'day.
I live in the tropical north of Australia at present. We have two seasons - a wet and a dry - so we have a limited range of temperatures during the year. The wet is our warmest time with very high humidity and temperatures between 75 at nihgt and 95 during the day on average.
I still manage to brew successfully in these conditions. I use either an Ale yeast or a multipurpose yeast and check my SG a couple of days early. Most brews have been ready to bottle in 5 days (I even bottled one after 4). Once in the bottle I place the brew in the place that has the most constant temperature of anywhere in the house. In this case, it's the Cyclone (Hurricane) shelter downstairs.
Brewing in warmer weather can be successful, you just need to experiment a bit.
Good luck and cheers,
Arch.

Are they all the same recipe?

If you are using carapis or dextrin you have unfermentable sugars, so you will have a higher FG when everything is fermented out. This will give your beer more body.

The higher temp will give you more esters as mysterio said. If temps get much higher than 75* you may start producing fusel alcohol which will give you that sharp taste.

mysterio said:

Basically you're going to get some extra fruity esters in the beer and the possibility of higher 'fusel alcohols'.

Click to expand...

That and some headaches.


As for your fermentation, it sounds like you have a mash problem. I think you mentioned that these were All Grain brews. Did you check for conversion? Are you sure you hit your temps? If your process was good, you may have got your hands on some under-modified malts - i.e. bad grain.

I have had this happen before - with a Blueberry Wheat. Unexplainably, my fermentation stopped at 1.025 or so. I know that the yeast was still active because I added more fermentables (fruit) to the fermenter and it took off again until those sugars were gone. Finally, I decided that I had some bad grain that was not fully modified or that I screwed up the mash somehow - cold spots, etc.