Imperial Stout

[ACBEV]

I'm going to have a go at brewing an Imperial Stout (Courage 1914 recipe, slightly modified!)
http://barclayperkins.blogspot.co.uk/2012/02/lets-brew-wednesday-1914-courage.html

I don't often brew big beers, generally around 3-5% is my mark, due to falling converion with over 5kg malt. So I've subbed 4.5kg of pale malt with LME, which leaves 5kg of malt to mash. I'm intending to combine the LME and mashed wort together before boiling and then using two fermenters (2 x 12L) with a packet of yeast in each. After 7 days fermenting I will empty one fermenter into the other and leave for another 21 days. Then bottle and condition for next Christmas/New Year (10 months).

2000g - Pale Ale Malt - 21.1%
1800g - Brown Malt - 18.9%
800g - Black Malt - 8.4%
400g - Wheat Malt - 4.2%
4500g - Muntons Light Liquid Malt Extract (added to boil) - 47.4%

60g - Fuggles - 60 min
50g - Hallertau Mittelfruh - 30 min
40g - Fuggles - 15 min

Batch Size: 23L - 24L
Mash @ 67c 2 hours (Double mash, 2 x 1 hour)
Boil 1 hour
2 x Wyeast - West Yorkshire 1469
ABV: 10%

I just need a bit of reassurance that my method is good or maybe not!

 

[Sadfield]

That looks a good way to navigate the efficency drop of mashing high gravity. I would recommended using some yeast nutrient though, due to both the high gravity and also extract usage.

 

[Poochops]

Are you thinking of mashing all the grain as normal, then adding the DME before boiling? That's how I'd approach it, it would be ideal. If I was doing it in the gf I'd expect an OG about 1.116 FG about 1.030, for about 11.3%, Your yeast is good for just 9% so you might reconsider that. Also I know you didnt ask for recipe tips but brewers friend is calculating 30 ibu's but the style is ideally 50-90, bittering with 40g magnum would give you 51 ibu's, if it were me I'd go with 50g magnum for 61ibu's but that's down to personal taste. I'd kick the 30mins out to 15 as well, I don't think it's doing much for flavour at 30 mins, but you'd lose a few ibu's.
Bet it will be lovely! I've got a partial mash RIS bottled last March and it's beautiful now, almost too good to drink and only about 20 small bottles left.

 

[ACBEV]

@Sadfield, I will look at yeast nutrient.
@Poochops... Yes grains as normal and adding LME to wort before boiling. The ABV did strike me as high for the yeast, but my calc comes out as 9.93%, may or may not push the envelope. For my batch size 22L, my stats come out at OG: 1.108 FG: 1.032 IBU: 64.

I think I'm leaving hops as is, but now I'm scratching my chin over the yeast...

I think I might go out on a limb with the yeast and opt for Belgian Ardennes 3522. Its not a typical Belgian yeast, I've used it before and is good for all-sorts of beer and will handle 12%

One of the great and versatile strains for the production of classic Belgian style ales. This strain produces a beautiful balance of delicate fruit esters and subtle spicy notes, with neither one dominating. Unlike many other Belgian style strains, this strain is highly flocculent and results in bright beers.​

 

[Poochops]

Yep, different system efficiencies different outcomes I guess. Ibu calculations do seem to differ wildly depending which calc is used, I think the best way is a pencil and calculator but generally can't be arsed! Do post your OG when you brew, just out of interest.

 

[Sadfield]

Ardennes sounds interesting, I've used a Belgian yeast in an Impy and think it works really well if you control the temperature. I used WY1762 Abbey 2.

 

[ACBEV]

Funny thing is, I was in brewing shop looking for London Ale III, but they didn't have any. I bought Ardennes because it had similar spec. flocculation and attenuation! I've brewed all-sorts of beer with it since, very nice yeast indeed.