Hops Absorption: Am I On to Something?

[Brewer #141799]

Hey Brewer Friends,
I have been banging my head against the wall for a while trying to solve a problem with inaccurate and inconsistent water volume calcs and in turn, predicted gravities.

I am now wondering if it is my hop absorption rate. I have it set to the default .15 qt/oz in my profile. I also have 1 qt dead space in my kettle. I just throw loose pellets into the kettle and after whirlpooling they settle into the dead space. So I'm thinking that I am double dipping on the deductions. Yes, I am losing the 1 qt in the dead space, but I am not also losing an additional .15 qt/oz of hops I use. Does this make sense?

If so, it would explain why the variances I see are never consistent - because it is tied to whatever amount of hops the recipe calls for.

Should I keep the dead space number and set hop absorption to 0.

 

[ACBEV]

This may not be helpful, but hay ho.... My kettle dead space is 0. i.e. everything from the kettle goes into the FV. I find this is reasonably consistent. Just the way I do it.

 

[GFHomebrew]

Hops do absorb some wort especially as I do too throw them in loose. If they were in a bag you can squeeze out some of that absorbed wort.

 

[Mark Farrall]

I've also turned mine down to virtually nothing (I squeeze the bags), but it doesn't really make much of a difference in the problems I had tracking my inconsistent water numbers.

Mine was easy to ignore, if I put the calculated amount in at the start I kept getting the right amount out at the end. I thought it must be boil off rate, so I kept changing that to get the right final result, but the intermediate numbers were nowhere near the calculator numbers.

I ended up increasing my boil off significantly and really cuttting down the grain absorption rates to get the calculator to behave. I think I may be using the mash bag as a stress relief tool which was getting a lot more out than expected. I've since changed to a mash basket and it's even easier to get more mash water out.

 

[Nosybear]

Hey Brewer Friends,
I have been banging my head against the wall for a while trying to solve a problem with inaccurate and inconsistent water volume calcs and in turn, predicted gravities.

I am now wondering if it is my hop absorption rate. I have it set to the default .15 qt/oz in my profile. I also have 1 qt dead space in my kettle. I just throw loose pellets into the kettle and after whirlpooling they settle into the dead space. So I'm thinking that I am double dipping on the deductions. Yes, I am losing the 1 qt in the dead space, but I am not also losing an additional .15 qt/oz of hops I use. Does this make sense?

If so, it would explain why the variances I see are never consistent - because it is tied to whatever amount of hops the recipe calls for.

Should I keep the dead space number and set hop absorption to 0.

Actually, you'd have to use 2 ounces of hops to lose a cup of wort - the variance from other parts of the process (the boil, measurement error) are larger than this so while you might be getting some inaccuracy there, I'd look to other places to find it. If it were the problem, your volumes would be consistently (statistically speaking) larger than expected by the 0.15 qt/oz.

 

[ACBEV]

@Nosybear has hit the nail on the head. For consistency you need to know what effect your equipment and processes have.

Whatever I'm brewing, I know I will bottle between 40 and 42 500ml bottles. Big beers tend to be 40 and small beers 42. In all a 5% margin in production, the difference mostly accounted for by trub.

Before I start brewing a recipe I know exactly how much water I need to get 23L in my FV, give or take 0.5L.

To the 23L I add my mash tun losses, for 5kg of malt I allow 1L per kg, plus 0.5L for dead space So now my total is 28.5L.

Now I add in boil off. My boil off is 0.91L per minute. So for a 60 minute boil that would be 5.5L added to 28.5L = 34L

I don't account for any kettle dead space, it all goes in the FV.

With my equipment and process and some simple maths, my margin is 0.5L. If I'm below my mark by a bit, I just top-up to my 23L line.

I don't think it has to be any more complicated to be reasonably consistent.

 

[Nosybear]

And you can always adjust with boiled, dechlorinated water or DME. Hitting numbers is never as important as making good beer. Concentrate on the latter and learn, like any good craftsman, to "fudge" where necessary. 0.15 qt/oz hop absorption is nothing to be concerned about.