Bells yeast underattenuation

[SterlingHopper]

I just brewed a hoppy amber ale:

9.5 lb Vienna
1 lb Crystal 40
1 lb Munich
1/2 lb Biscuit

Mashed at 155* for nearly an hour. Mashout was a little long (maybe half an hour?). Hopped with Centennial and Ahtanum to 40 IBU.

OG: 1.064

I used the Bells yeast strain, which I washed from a previous batch. I had harvested it from a couple bottles of Two-hearted and split a brew (Yooper's cream ale), with half the batch getting 1056 and the other half getting the Bells yeast. Both yeasts took this beer down to 1.009 (from 1.045).

After 2 weeks in primary, my amber's gravity was 1.022. One week later and I'm still at 1.020, only 69% attenuation! Even with this malt bill and high mash temp, I was expecting an FG closer to 1.015. So, today I racked to secondary to rouse the yeast a little.

I pitched at about 66*, and it settled to 64* within the first couple weeks. BTW, I made nearly a 1.5qt starter for this batch and aerate by simply shaking the fermentor like crazy.

Is my poor attenuation due to the mash temp, the grain bill, or too low fermentation temp for this yeast? Anybody have experience using the Bells yeast strain?

 

[weirdboy]

So it's 15% crystal malts and mashed at 155F....that doesn't seem particularly wide of the mark to me.

 

[Reelale]

I just brewed a hoppy amber ale:

9.5 lb Vienna
1 lb Crystal 40
1 lb Munich
1/2 lb Biscuit

Mashed at 155* for nearly an hour. Mashout was a little long (maybe half an hour?). Hopped with Centennial and Ahtanum to 40 IBU.

OG: 1.064

I used the Bells yeast strain, which I washed from a previous batch. I had harvested it from a couple bottles of Two-hearted and split a brew (Yooper's cream ale), with half the batch getting 1056 and the other half getting the Bells yeast. Both yeasts took this beer down to 1.009 (from 1.045).

After 2 weeks in primary, my amber's gravity was 1.022. One week later and I'm still at 1.020, only 69% attenuation! Even with this malt bill and high mash temp, I was expecting an FG closer to 1.015. So, today I racked to secondary to rouse the yeast a little.

I pitched at about 66*, and it settled to 64* within the first couple weeks. BTW, I made nearly a 1.5qt starter for this batch and aerate by simply shaking the fermentor like crazy.

Is my poor attenuation due to the mash temp, the grain bill, or too low fermentation temp for this yeast? Anybody have experience using the Bells yeast strain?

I would say fermentation temperature. I just brewed 10 Gallons of THA clone with harvested yeast from, well, Two Hearted Ale. I pitched at 64 and let it rise to 70 towards the end of fermentation. That's the temp the recipe in BYO calls for. There is also a recipe from Zymurgy floating around here somewhere. Mine finished right where it was supposed to, 1.012. I'd warm it up.

 

[GuldTuborg]

So it's 15% crystal malts

Where does this number come from? It looks more like 8.3% crystal to me.

I'm sure you already questioned pitch rate. If your washed yeast was old, you might have pitched a small number of healthy cells, despite the starter size. When in doubt, though, rouse and warm. Try that for a few days, then reassess.

 

[SterlingHopper]

doesn't seem particularly wide of the mark to me.

Yeah, I'm still learning how all the variables come into play when crafting a recipe. Also, this is the 3rd batch we've done with the new all-grain mashtun cooler setup, and the water volumes aren't consistent every time. This beer was supposed to hit 1.060 at 5.25 gal, but came out 1.064 at 4.6 gal.

Moving to a warm room today.

 

[permo]

that does seem a bit strange. In my experience the bells yeast is a maltose monster. At 1.064 I think you likely underpitched just a little bit.

When I used to use the bells yeast I found that it loved the 70-75 degree range.