eVAPORATION HELL

[Bushmaster]

Greetings to one and all.

I did a brew today, all went well, its now settling into its primary fermentation. However, I did notice that during the boiling stage my original quantity of 23 litres was whittled down to about 15-16 litres during the 90 minute boil.

BASICALLY!!:- Am I stuck with 15 litres of beer or can I top up with water?

Please help,

Cheers, Bushmaster.

[hotmog]

That sounds a lot. Normally you would allow for a 15% loss to evaporation during a 90 minute boil. Don't forget as well, however, that you need to allow for another 2 - 3 litre loss to the hops and trub, plus any dead space in your boiler.

You can water it down, although it's probably a bit late now if fermentation is already under way. Did you check the OG before you added the yeast? That would at least give you some idea of how much, if any, top-up water to add to achieve your target gravity.

[WishboneBrewery]

Your website Hotmog....

Thats some fine collection of toilet Chain pulls you have Its good that people show love to old things that are worth preserving

[Bushmaster]

Well, I've made a gamble........

I took an OG of 1050. The recipe was aiming for 1042. On an all grain website it suggests dropping the brew into another bin 48 hours from the start to leave trub behind. So, after the brew had been dropped into the second bin I took a hydrometer reading of 1036. My gamble was to reduce this to 1028 by adding water. This made the volume up to 18 litres. And I lost the extra .008.

May end up being drain cleaner, but t least its a learning curve. What do you reckon?

Regards

The Bushmaster

[Matt]

You should be alright Bushmaster.

Your query made me work out my evaporation losses - I get about 28% which is about what you got.

My routine (picked up from advice on here) is to mash with 3 litres of water per kilo of grain; fly sparge with 22.5 litres of water. That makes circa 32 litres pre-boil and circa 22.5 litres as a post 90 min boil volume (with circa 100g of hops in the kettle).

Matt

[Bribie]

What you have basically done is what many commercial brewers do, you have brewed 'over gravity' and like them you need to adjust the beer to 'sales gravity', i.e. water it down At this stage ordinary tap water will do, but if you were to ferment the beer right out, you can still water it but using de-oxygenated water, i.e. boiled then cooled rapidly in a container where it can't pick up oxygen.

Personally I find that when boiling with a 'rolling boil' and with another brew a slightly harder boil the difference can be striking as to the amount you lose to evaporation, and with a 24 L batch I often have to put a couple of kettles of boiling water into the kettle to bring it back up to where it should be.

[blackadder]

I have not had problems with adding water post boil and even into primary fermentation. Tend to use supermarket mineral water. Once the primary has finished its a completed recipe and I wouldn't touch it.

[subsub]

I usually get 17% evap so go for 20% in my figures and thats at over 400l. If you batch sparge you can muck about Daabs calculator and adjust for your system