Topping up after boil to maximize yield

[Wheelspin]

I would appreciate your comments on a technique for maximising my after boil yield that I've been using for years.

I have a 75 L boil kettle. I formulate my my recipes for 75 L after boil volume.

I start my boil with about 72 L which after an hour leaves me with ± 66 L (about 6 L boiled off).

I then top up my boiler with ± 9 L of pre-boiled water to bring it back up to 75 L. This is then chilled and pumped into fermenter.

Can any comment on why I should, or should not, be doing this ?

Your views would be appreciated.

ipe:

 

[ncbrewer]

If you formulated the recipes for 66 liters to avoid needing to top off, the lautering efficiency would be a little better. And hop utilization could be a little better. If you're ok with these, I don't see a problem.

 

[bajaedition]

what he said

you can just add the water to the fermenter if you want, it has been pre boiled and cooled.

 

[Wheelspin]

Thanks Guys

I need to maximise my output so settling for 66 L yield when i can get 75 L is not really what i'm looking for.

Currently Im getting around 82 - 85 % efficiency but I just wondered if there where any downsides to this method.

 

[pepindavid]

I do something similar (in a biab setup), but I simply top up with cold water (treated with Campden tablets). Never had a problem. Compared to adding to hot wort, it speeds up the cooling process, and it avoids excessive hot side aeration (I know, is HSA actually a thing or not, etc., but why risk it?).

 

[mrdauber64]

You loose hop efficiency by adding water post boil. A partial boil is not ideal, but can still produce good beer as long as you adjust you up your hops to counteract the water being added.

 

[Mainer]

I do this with most of my beers.
I have a five gallon kettle, in which I boil at about 4 gallons.
After the chill, I top with about a gallon of tap water straight in the fermenter.
As others have said, you lose some hop efficiency, but unless you're building a hop monster, that's usually not a bid deal. Most of my brews only have 2-3 ounces of hops anyway.

 

[bajaedition]

My fermenter is marked for 5.5 gallons

that is my target. such as you are targeting 75 liters

I technique is to cool whatever is in the boil pot after the boil and cool down, then pitch with my 1 liter starter, then I can fill to the 5 gallon line with cooled water that was pre boiled.

that way I get my target 5.5 gallons

my recipes are adjusted foe 5.65 gallons, I figure I leave .15 gallon in the pot of trub.
and I get 5 gallons into the keg leaving .5 gallons in the fermenter with heavy lees in it.

the amt of DME in my starter is figured into my recipes.

I know that is a little anal retentive, but it is my what I want to do.