Top up during/after boil full grain boil off

[NeoY2k]

Hello,

I have a 35l kettle and brew outside on gas. I have quite a lot of evaporation, if it is cold and dry outside it can be almost 30% boil off.

If I compensate for this boil off at the mashing stage, it either doesn’t fit in my kettle (or boils over, depending on the recipe), or I have to brew to a smaller volume in the fermenter.

Obviously if I don’t compensate I have too high initial gravity.

I was thinking of compensating the boil off by periodically adding boiling hot water throughout the boil to maintain pretty much the pre boil volume, or in other words maintaining the constant desired initial gravity by adding boiling water during the boil.
My understanding is that would have zero ill effect, am I correct ?

Or alternatively, letting the wort concentrate by evaporation, and then add boiled then cooled water at the end of the boil to dilute back to desired initial gravity. The cooled water having the added bonus of helping cool the wort faster.
There might be added infection risk, and lower hops utilization, that might be counter balanced by adding about 10% more hops.

Or just had that water boiling hot at the end, same result except slower cooling but less infection risk.

What is your opinion on this?

Thank you,
Nicolas

 

[SFC Rudy]

Adding water will work, extract brewers do it.

Try to control the boil. If you’re having 30% boil off turn the heat down. Once liquid starts boiling it doesn’t get hotter, it just releases more heat, and moisture, into the atmosphere. You don’t need a full rolling boil.

 

[DBhomebrew]

A different approach with a reduction of wasted energy.



A low 'level 1" boil is all you need.

 

[kevin58]

Instead of adding water maybe try withholding some of the wort from the mash and then add it back toward the end of the boil. That way you are not diluting your product.

 

[day_trippr]

Simple solution: turn the heat down!

Cheers!

 

[mac_1103]

Instead of adding water maybe try withholding some of the wort from the mash and then add it back toward the end of the boil. That way you are not diluting your product.

Let's say I have 7.5 gallons of 1.040 preboil wort and I want to put 5.5 gallons of 1.055 wort into my fermenter. But oops, I boiled off a half a gallon more than I wanted to. So now I've only got five gallons of wort but the SG is 1.060. What's wrong with adding back a half a gallon of sterile water? Yeah, I guess that would be diluting the wort, but only because the wort came out too concentrated in the first place.

 

[keystonehb]

If I compensate for this boil off at the mashing stage, it either doesn’t fit in my kettle (or boils over, depending on the recipe), or I have to brew to a smaller volume in the fermenter.

Are you not sparging on brew day? 35L (or 9.2 gallons) should give plenty of room for a full boil for a 5 gallon batch. Assuming 30% loss you should need about 6.5 gal in kettle, a little more or less equipment dependent.

 

[pvpeacock]

I used to make 10 gallon batches of beer in a brew kettle that only held 7 gallons of wort. I simply made a high gravity wort of just under 7 gallons during the mash. After the boil, I divided the wort into two fermenters and added top off water directly into the fermenters to get just over 5 gallons into each.

 

[MaxStout]

If too much boils off, yes, you can top up post-boil. You're really only replacing water that evaporated off.

If you're worried about boilovers a few drops of Fermcap-S when the boil starts will knock down the foam.

 

[NeoY2k]

Thank you very much. Will check how low I can boil (given the temperature, I'm more concerned about it not boiling), as this seems the major reason of my excessive evaporation (that and a kettle that is a bit wide ish). And top up water if needed.

The kettle is enough to brew 5 gallon batches full volume accounting evaporation, but with the fixed losses of the bottom of the kettle and the trub in the fermenter, I prefer to brew for 7 gallons in the fermenter, that way I'm less upset in % about the losses. But yeah it is homebrewing being upset about a lost pack of beers is a bit silly I admit.

dBHomeBrew especially thank you for the reference. That video and the advice that 1 is all that is needed, and the topic about simmering with the lid on and only finishing with the rolling boil is very interesting and I will be following these advices from next batch on!

Thanks,
Nicolas

 

[Closet Fermenter]

A different approach with a reduction of wasted energy.



A low 'level 1" boil is all you need.

Thank you for this! This is the answer to a question that I have wondered about for some time. Even last night, I was skimming through a homebrewing beginner’s guide that I am intending to pass along, and I read that:
“Malt and hops are not merely combined in hot water to form wort, they are boiled violently for an hour, ridding the malt through collision and coagulation of its raw haze and off flavor proteins, and evaporating excessive aromatic hop oils while converting insoluble alpha acids into dissolved hop flavor.”

I have over the years reduced my boiling “violence” with no noticeable effects except less boil over risk and laster longing propane tanks. I am also more comfortable stepping away from the pot a minute or two to do a little cleanup or prep the fermenter. Your information indicates that the “violent” boil is unnecessary. Good to know.

 

[day_trippr]

A "hard simmer" is really all that's needed

Cheers!

 

[Bassman2003]

Thank you very much. Will check how low I can boil (given the temperature, I'm more concerned about it not boiling), as this seems the major reason of my excessive evaporation (that and a kettle that is a bit wide ish). And top up water if needed.

The kettle is enough to brew 5 gallon batches full volume accounting evaporation, but with the fixed losses of the bottom of the kettle and the trub in the fermenter, I prefer to brew for 7 gallons in the fermenter, that way I'm less upset in % about the losses. But yeah it is homebrewing being upset about a lost pack of beers is a bit silly I admit.

dBHomeBrew especially thank you for the reference. That video and the advice that 1 is all that is needed, and the topic about simmering with the lid on and only finishing with the rolling boil is very interesting and I will be following these advices from next batch on!

Thanks,
Nicolas

I think you have a few choices to solve your problem. But I think you are creating the problem yourself. Some steps to consider:

1) Lower your trub. Try to only transfer clear wort from the mash.
2) Aim for 5.5 gallons into the fermenter instead of 7 gallons. You are needlessly pushing your pot size limits as well as making things harder on your yeast.
3) Lower your boil intensity. You can use higher heat at the begging to get a decent hot break but after that lower it. 30% evaporation losses is way too much. Aim for under 10%. For example, I try to only boil off .5 to 1 Plato of gravity in 60 minutes. So if preboil gravity is 11.5 Plato, my end of boil gravity would be 12-1.5 Plato.

 

[odie]

how about this...

since your kettle is too small, change nothing....but add no water to the boil.

as you boil down, sparge the mash some more for your lost boil volume.

So instead of adding water to make up the boil off...you are adding extra wort. It will not be full strength but there is still sugar in the mash.

And you only need a low boil...not crazy...even just simmering is fine.