Adjusting for FG by decreasing efficiency?

I thought of many ways to ask this question, here is the simplest way I can think to ask.
If I want to replicate a beer, lets say it has an ABV of 8.4%, and I repeatably get a FG of 1.020 (wyeast 1056), I look at a ABV calculator and it tells me I need a OG of 1.084.
This is making me think my efficiency can be good (78%), but ultimately is a slave to attenuation of my yeast.
I have also never gotten a FG below 1.020 with Notty and London ale yeast.

My question is: Do I have to increase my grain bill (lower my eff.) in order to get a higher OG knowing my FG will not be lower than 1.020.
Or do I do something different with the yeast to get a lower FG.

Know what I mean?
Cheers

The simple answer is to increase your attenuation. If you're brewing extract batches, though, there isn't much you can do about the lowered fermentability of some of the extracts you're using. I'd try a different brand/type of extract.

For an all grain batch, simply reducing the mash temperature and rechecking the ingredients for fermentability would fix it.

I mash in about 157 and it's about 152 after 1 hour. Come down a couple degrees?

runkelia said:

I mash in about 157 and it's about 152 after 1 hour. Come down a couple degrees?

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You are losing 5 degrees an hour? That is a lot. Mashing lower will definitely bring you below 1.020, as will raising ferm temps after a few days of vigorous fermentation.

runkelia said:

I mash in about 157 and it's about 152 after 1 hour. Come down a couple degrees?

Click to expand...

Do you preheat your MLT? Is it a cooler, or a kettle/keg? If you preheat, and somehow insulate, you shouldn't lose anywhere near that.

I'd definitely mash at 150, and hold it there if at all possible. That will really make a difference in your attenuation.

Have your beers been really full bodied, and a bit "thick" with mashing at 157? I've never gone that high, except for one beer I mash at 156 (oatmeal stout).

Yooper said:

Do you preheat your MLT? Is it a cooler, or a kettle/keg? If you preheat, and somehow insulate, you shouldn't lose anywhere near that.

I'd definitely mash at 150, and hold it there if at all possible. That will really make a difference in your attenuation.

Have your beers been really full bodied, and a bit "thick" with mashing at 157? I've never gone that high, except for one beer I mash at 156 (oatmeal stout).

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I have attached a photo of my awesome mash tun, given to me by my dad.
It is a 48 qt. coleman vintage 1980. See how the lid doesn't seat? I have to put 20lb dumbells on each corner. Anyway I pre heat that bad boy by adding strike water of 180 deg, let it sit for 10 minutes then mash in, that gets me to 157.
Not too thick, actually made a porter a couple months back I though could have been fuller. Next brew maybe I will take 5 degrees off, strike at 175.

You could throw a sleeping bag (or two) over it, and/or put some foam insulation over the mash to help hold in the heat. Losing a degree or two is ok over an hour, but 5 degrees is a lot.

Mashing for an hour is overrated - lower your initial strike temp to 150, mash for 20-30 minutes, check conversion with iodine, and you'll solve your problem.

With that lid I would get a piece of 2" rigid foam insulation and make a "lid" to friction fit underneath the existing lid...I do this with my cooler and set it a couple inches above the grain bed.

Mash lower 150-152. The iodine test works great for B-amylase but gives no indication about completion of A-amylase (branched starches). There is no downside to mashing for 60 min or even a little longer at the lower temps.

Well the downside is the amount of time, which to me is my most expensive brewing ingredient!

Give a short mash a try sometime and I think you'll find you get the same results. The enzymes are denaturing throughout the mash so how many are still active at the end of that hour? Not to mention your lauter process adds some time, so if you don't mash out then you've got more opportunity for conversion.

Is is possible that you are under-pitching or fermenting at the low end of temperatures?

I always make a starter based on what brewers Friend starter calculator says I need, and I ferment at 65, wyeast says the temp range for 1056 is 60-72.

Maybe it's equipment? Have you checked the accuracy of your hydrometer? It should read 1.000 @ 68° (assuming that is what it is calibrated to).

Sometimes the simple things are overlooked.

Cheers

Mash at a lower temp, use a good sized starter, oxygenate the wort better before pitching.