Reduced-volume boils

[Sandimas]

I've always done reduced-volume boils due to restrictions with my BIAB setup, typically a 10L boil then topped up in the FV to 17L. It's always produced good beer so I haven't given it any thought. However, came across the Brewer's Friend calculator and was a bit shocked at how many IBUs I'm losing
https://www.brewersfriend.com/ibu-calculator/

So I thought I'd plug in some figures from one of the big homebrew providers extract recipe packs, and given they suggest an 8L boil for 19-23L brews the loss of IBUs was again surprising. Just wondered why they don't compensate for the reduced volume boil by adding more bittering hops?

For my next brew I'm going to try compensating and see what the effect is.

Anyone else do reduced-volume boils, do you compensate or not?

 

[matt76]

I've done it, and worked through the maths - i wrote about it here.

It's really only when you are liquoring back significantly that you need to worry about it.

It's an interesting exercise but frankly a pain on brew day to keep working stuff out on the fly - i prefer to plan my brew, brew my plan, and well if the numbers come out a bit different, meh, I've still made beer.

 

[Drunkula]

Anyone else do reduced-volume boils, do you compensate or not?

Yep, I work out the IBUs for the final batch, then put the reduced batch size into BeerSmith and multiply the IBUs by the ratio of the full volume to the reduced. I did a few calcs to see what the price difference is with different hops - it's nothing on high alphas. I also did a comparison on a 60 and 30 minute boil - save half hour boiling and only spend 13p more - oh yes.

----------------------
To dilute 14 litres down to 23 I'd need to get an 49.6 IBUs to get back to 30.2 using:

Target 10.8%: 24g vs 30g, 11p difference
Admiral 13%: 20g vs 25g, 8p difference
Cascade for 40 IBUs 63g vs 79g, 13g 67p difference

Length of boil differences in cost 60/30 boils for 30 ibus
Admiral 20g vs 26g, 9p difference
Target 24g vs 31g, 13p difference
Cascade 47g vs 61g, 59p difference

 

[Llamaman]

Can’t you get around this by putting some of the extract in as a late addition?
Lower gravity boils get more IBUs from the hops.

Brewers Friend let’s you set the boil volume separate to the fermenter volume so you can work out your hop bill to hit a desired IBU.

 

[MyQul]

I've done this a lot and never bothered to add any extra for reduction of boil volume and not found and difference. I suspect it's because I normally do low gravity beers with low hopping rates. If I were to make big beers using this method I'm guessing I would need to add extra hops

 

[Clint]

Had to laugh...
Reduced volume boils ...sounds like a painful skin condition ..

 

[Sandimas]

Thanks all, I'm keen to try it to see if I notice any difference so I'll make one of my regular 1045 pale ales and compensate to try to get the target bitterness and report back.

 

[Braufather]

Quick question- about topping up. ive never done this before as ive just settled for a higher gravity if thats' what ive ended up with, however thinking of giving a go next time if needed.

I use bottled water and thinking the best time to do this would be at flame out if needed- with the wort being still boiling this would sanitise the water plus accelerate the cool down. Any reason i shouldnt do this? i know most people add direct to FV, but i guess that would mean boiling and cooling first.

 

[Llamaman]

I don’t see why you would boil bottled water. If it’s a newly opened bottle it should be fine to bung in as is.
Tap water is also fine as long as it’s not sat in a hot water tank (I have a combo boiler).

 

[matt76]

Just bung it in after you've chilled your wort and checked the gravity - I've done this loads of times with freshly opened bottles of Tesco Ashbeck.

Top tip: give it a very thorough stir after dilution if you plan to recheck the gravity! Otherwise it might not be mixed and you'll get misleading numbers!

 

[Braufather]

do you sanitise the top of the bottle at all? i take it as a rule of thumb works 1 litre will reduce gravity 5% (based on 20 litres) so 1060 would become 1057?

 

[Nicks90]

I often dilute and never bother with anything other than tap water. I give my jug a quick squirt withh antibac and the just rinse it off and get on with pouring in the extra water.
Beer wants to be beer.

 

[matt76]

do you sanitise the top of the bottle at all? i take it as a rule of thumb works 1 litre will reduce gravity 5% (based on 20 litres) so 1060 would become 1057?

No, just bung it in - as long as it's freshly opened there and then, or earlier that brew day, then I don't have a problem

 

[Gerryjo]

If anyone is diluting with bottled water put it in the fridge or freezer to cool down before adding bringing it closer to Fermenting temp and giving a more accurate reading for dilution.

 

[Gerryjo]

If needed I just use tap water btw.

 

[Braufather]

ok cheers chaps

 

[MyQul]

Quick question- about topping up. ive never done this before as ive just settled for a higher gravity if thats' what ive ended up with, however thinking of giving a go next time if needed.

I use bottled water and thinking the best time to do this would be at flame out if needed- with the wort being still boiling this would sanitise the water plus accelerate the cool down. Any reason i shouldnt do this? i know most people add direct to FV, but i guess that would mean boiling and cooling first.

As others have said just bung the dilution water in straight from the tap. You dont need to sanitise anything (e.g. the jug you fill up to collect the water). Ive been doing this for years and never had a problem. You can dilute at any stage pre or post fermentation. You just need to be careful not to oxidise your beer if you do it post fermention

 

[Braufather]

Warming to this idea now. I’ve a recipe book where 90 per cent of recipes are over 6-7 %. Next time I try one I may split the batch and put 9 litres in a ten litre Fv and maybe dilute the rest down to what would give me a 4% session beer and put in a normal fv. I’d compensate with a lot of dry hops no doubt and maybe a different yeast, but can anyone see any issues with this?

 

[phildo79]

I started off doing 10L boils. Then reduced it to 8L. My last batch was a 6L boil for a Sierra Nevada Torpedo clone. My total hop weight (including dry hopping) was 147g. I did have to tweak the hop additions to compensate for the AAU's of the hops as they were different to the recipe but the total weight was exactly the same, 147g.

Interestingly, the IBU's calculate at 73 Rager and 93 Tinseth. The recipe quotes 70 IBU.