a few general questions to help me understand why my gravity didn't get low enough.

hey HBT,
i have a few questions that will hopefully help me understand 1) why my beer didn't ferment down low enough, and 2) the more delicate processes of yeast and how to better ferment my beer next time around.
First i should make it knowledge that i am fermenting a British Bitter using 7lbs morris otter, .75lbs caramalt, and half a pound of caramel 40, and Windsor Ale yeast. The target OG for this batch was 1.040, and my actual gravity that i recorded was 1.046, a little high but i think that was do to an unexpected amount of boil off as i was using a new system and hadn't tested it out prior to brewing. i have taken two gravity readings so far, one at 4 days and another at 8days, the first at four days was 1.024 and the second at 8 days was 1.022. these are no where near the suggested final gravity of 1.012 even with the higher recorded gravity taken into account. This leads me to believe that either my fermentation techniques need to be severely looked at, or i should start using some sort of yeast nutrient in my brews as it looks like they are not working at full capacity.
The Windsor Ale yeast is recommended to work properly between 60-70 degrees F. My house gets rather warm in the summer months and is generally between 70-75 F. In order to compensate for that i created a makeshift fermentation chamber out of a spare cardboard box that i had laying around with the bottom cut out and placed over an air duct in my house. This system works ok generally allowing the temperature to fluctuate between 65-71 degrees, however in during the first 12 hours of fermentation the heat generated rose the temp to above 75F at times.
So what i'm asking the community is would this wild temperature variation be enough to cause low yeast activities that are leading to less fermented beer? Also, what are ways to better ensure my fermentation gets done properly? Finally, do you have any other tips or general advice that will allow me to properly and constantly ferment my beer in the correct fashion?

-Zach

First: No need to measure gravity if its obvious that its fermenting. Its a waste of beer. Let it ferment for 2 weeks minimum before you even think about checking gravity.

Second: Let it ferment. It might take the beer up to 3 weeks for fermentation to subside/slow down and gravity to stabilize. You might get it close to 1.012 if you wait long enough.

Third: No yeast nutrient needed.

Fourth: You are fermenting on the warm side, so if anything your beer may end of over-attenuated (i.e. lower than predicted OG). Your temp. control is probably OK though. An improvement would be having a way to control the temp in that initial burst of fermentation activity where the yeast are producing lots of heat. At this stage of your fermentation, what you are doing is OK.

Fifth: Sounds like you did an AG brew...what temp did you mash at? That affects the type of fermentable sugars that are produced and thus would affect your FG/overall fermentibability. Higher mash temps mean more unfermentable sugars which means a higher FG.

Give it some time, you might be surprised....good luck!

thank you broadbill, you have slightly eased my worries some. Yes i did do an all grain kit and i mashed it at 156F. This is one of the first fermentations that i'm watching diligently to get a feel for how it works and what it does, that might explain my manny samplings. What would you suggest to do as far as temperature control?

Mashing at 156 is pretty high, and will result in a higher FG. Using 1.25 crystal malt will also contribute. If you did a thick mash (about 1 qt per lb), that could also cause a higher FG, and starting at 1.046 instead of 1.040 would also have an effect. Add them all together, and I expect your FG will be considerably above 1.012. However, your gravity is still dropping, so I would leave it for at least another week, and preferably 2 weeks. It will probably drop several more points before it has finished.

-a.

Just to touch on one thing: I would get some yeast nutrient and just start making it a standard procedure to add it when you add your Irish Moss/Whirlfloc. You don't need it per se but it can't hurt and should help in those cases where the yeast isn't quite as healthy as you'd like.

Pretty much what everyone said above, and that Windsor is a low-attenuating yeast, it is notorious for that. I was surprised that no one said that yet! Try Nottingham or US-05 for a good general ale yeast.

agroff383 said:

Pretty much what everyone said above, and that Windsor is a low-attenuating yeast, it is notorious for that. I was surprised that no one said that yet! Try Nottingham or US-05 for a good general ale yeast.

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That and the high mash temp would account for a higher finishing gravity.
Leave it for another week and check it. It should be done by then.