Ramping up fermentation temps question

[rdavidw]

I have a pair of individuality temp controlled fermenters with stainless coils on glycol pumps and heating pads that I mostly use as primarys. I also have a pair of insulated but not temp controlled fermenters I use as secondarys or for wine, cider, mead and so on. I recently upgraded to the temp controls and have a question about ramping up temps on stuck fermentations.

I like big beers. I have a barley wine and a imperial stout fermenting now, five gallon batches. The barley wine is a 22lb grain bill with a OG of 1.110. 2L temp controlled starter on a stir plate with White Labs English Ale, decanted. I held the internal temp at 67 for two weeks and then racked and re-pitched with Red Star Montrachet Wine Yeast (also 2L starter) and came up to 68 degrees. After another four weeks, the gravity was still high at 1.045. I pitched Montrachet again, shook up the fermenter and bumped the temp to 72. Lots of airlock activity for about two more weeks. Then bumped temp up to 74 and airlock started up again. Gravity is now 1.031. I would like to end up under 1.025ish before kegging and storing at 36 degrees for about four to six months.

Here is my question - how hot can I, or should I go to keep the fermentation going? 80? 85? Will going that hot start growing anything other then the highly alcohol tolerant wine yeast or have any other bad effects?

The Imperial Stout was a smaller grain bill with a OG of 1.089 and is now at 1.028 with a similar fermentation plan, White Labs British Ale Yeast for the first 2L starter and then re-pitch Montrachet. The barley wine is tasting very good but a pinch too sweet at this point. The Stout taste hot but I expect it to mellow with a long cold storage.

Thank you in advance for any advice.

 

[Natdavis777]

Your off flavors will come from warm temps at the beginning of fermentation, not the end. So you are safe to up the temp. What was the grain bill if I may ask ans which English strain did you use. English strains tend to attenuate a bit lower unless coaxed, so that may be a reason for the high FG. Also, the grain bill may be holding the FG back. A

As for now, you should be safe to ramp up temps. For the record, Ive gotten 1068 to attenuate almost 80% given a low mash and temp raise at the end of fermentation, so English yeast can do some damage.

 

[rdavidw]

Thanks Natdavis777

The yeast was White Labs wlp002-english-ale-yeast

The grain bill:
17 lb two row
2.5 lb Crystal 20 L
2.5 lb Crystal 40 L
0.77 lb Acidulated Malt

Dough-in @ 110 for 20 min
Mash @ 152 for 60 min
Mash-out @ 168
Sparge with 180 in HLT - The last wort out of the MT was a gravity of 1.013. I may have gone too hot and got some tannin. I typically go cooler with smaller grain bills.

I started with 9.75 gallons, pumped 7.2 gallons of strike water to the MT and then added another 2 gallons to the HLT during the HERMS mash for a total of 4.55 gallons of sparge water. Boiled down to 5.5 gallons.

 

[Natdavis777]

You have a pretty decent amount of Crystal malt, more than 20% of the grist, so even with a 152F mash temp, you may be finished. in the future, try and keep the crystal % down some. For most beers, it is the norm to keep it around 5% or less. I know this can be difficult with stouts as you want to include roasted barley, choc malt, etc. Just be aware these grains can cause your FG to raise. So you may mash lower in the future or use less % of crystal/roasted malt