Topping Up The Kettle During Boil

[stuart]

Hi,

Do people top up the kettle during the boil to replace loss to evaporation? If not, why not? I often lose about 3L during the boil. Wouldnt the extraction of hop bitterness be more consistent if you could maintain the SG and volume of the wort?

-Stuart

 

[Keifer]

If im doing a 40-45 litre boil in my 50litre brew pot then yeah i top it up, also depends on what my volume/og turned out like.

 

[Yeasty]

I thought the idea was to figure out roughly how much u would lose, then sparge that amount extra when filling the kettle. Which would end up at your target volume...?

 

[Wardhog]

You formulate your recipes for the amount of wort left at the end of the boil rather than the pre-boil amount.

 

[Screwtop]

A recipe is just a starting place, a ratio of ingredients as parts of a whole. Knowing your system, a finishing volume and required amount of malt for the required OG and hops for the required IBU can be calculated.

I plug a recipe into beersmith and set the batch volume (post boil) to what I require and the efficiency figure to what I expect from the type of malt I'm using then adjust amounts of malt and hops to give the required OG and IBU for the volume. The correct way to do this would be to leave the efficiencyfigure at a known value for your system and adjust extract values for the different malts.

I simply sparge the mash until sugars are removed 1.010 rule of thumb, check the volume I have in the kettle (will depend on the malt and mash efficiency), calculate boil time for the required OG using the boil off calculator and work from that rather than just boiling for X time in every case. Boil times may range from 80 - 120 min.

 

[Fents]

I thought the idea was to figure out roughly how much u would lose, then sparge that amount extra when filling the kettle. Which would end up at your target volume...?

exactly.

 

[crozdog]

I do something similar to Screwtop in that I adjust the amount of grain & hops to obtain the desired OG & IBU for the known efficiency of my rig. I use Brewsta & factor in the amount of water I loose to grain absorbtion, mash tun deadspace, evaporation + what gets left in the kettle with the break/hops residue.

Once I have sparged & started the boil, I prop the mash tun up at one end, then every now & then drain a bit more liquor out & add to the kettle if it has some sweetness & isn't astringent.

 

[razz]

Hi,

Do people top up the kettle during the boil to replace loss to evaporation? If not, why not? I often lose about 3L during the boil. Wouldnt the extraction of hop bitterness be more consistent if you could maintain the SG and volume of the wort?

-Stuart

Morning Stuart. I top up my kettle to its original level so I can get the volume I require. I only have a 50lt kettle and I do 40lt brews to fill to 2 soda kegs.

 

[xtrabyte]

I do something similar to Screwtop in that I adjust the amount of grain & hops to obtain the desired OG & IBU for the known efficiency of my rig. I use Brewsta & factor in the amount of water I loose to grain absorbtion, mash tun deadspace, evaporation + what gets left in the kettle with the break/hops residue.

Once I have sparged & started the boil, I prop the mash tun up at one end, then every now & then drain a bit more liquor out & add to the kettle if it has some sweetness & isn't astringent.

If you add more liquor to the kettle from the mash tun after boiling for 60 minutes, do you have to keep boiling for 90 minutes after the addition? If not will you be under boiling part of the wort components?

 

[crozdog]

If you add more liquor to the kettle from the mash tun after boiling for 60 minutes, do you have to keep boiling for 90 minutes after the addition? If not will you be under boiling part of the wort components?

Sorry, I should have explained that I better. I add the extra liquor up until there is 10 minutes left. That way it gets at least a 10 min boil. As I typically do double batches or bigger, the % of extra liquor that only gets a short boil is small compared to the main runnings, I'm not fussed that they may be "under boiled".

 

[TasChris]

No you don't add water to replace the water lost to evap.
You need to think backwards with regard to volume, OG and bitterness etc.

What volume and OG do I need after the boil and in my fermenter?

To this volume you need to add
the volume lost to trub in the bottom of the kettle
the vol lost to evap
the vol lost to cooling ( 4%)


ie for my setup I want 26 litres in my fermenter so I need
26 litres plus
2.5 litres in kettle for trub plus
3.5 litres to evap plus
approx 1 litre for cooling shrinkage


so I need 33 litres in the kettle prior to the boil
and 29.5 after the boil, knowing that I will loose 2.5 to trub and 1 litre to vol loss for cooling to end up with 26 litres in the fermenter.


Thus my batch size is 29.5 litres of shall we say finished product so this should have the desired OG, bitterness etc that I want for my wert.
These numbers are for my setup, you need to measure your own losses and factor them in

Hope this helps