Boil Evaporaton Percentage

[jimmyjack]

what is everyones average boil eveaporation for a 90 minute boil. I am just trying to get an idea for beersmith calculations.

Cheers

JJ

 

[jimmyjack]

I reckon mines about 12 percent

 

[Aaron]

10-12% per hour is about normal. Do a boil and test it. It will vary depending on a number of factors including how hard your boils is and the size of your pot.

[edit] BTW it is probably better to edit your original post than add another post when they are one after another on the same subject.[edit]

 

[sosman]

I don't calculate based on percentage of boil volume. I lose around 10 L in 75 minutes. The major variation is due to how hard I boil.

 

[jimmyjack]

actually Sosman I was just looking at your website to refresh my thoughts on batch sparging and iodine tests. thanx for posting


cheers

jj

if the final volume i want is 21 litres and I over boil should I add the 1 litre to achieve the 21 litres like beersmith says?

 

[T.D.]

Funnily enough I was just revising my boil-off percentage last night. I use an immersion element which doesn't produce a boil that is as vigorous as a gas burner, but I get about 8% per hour evaporation. I just got a new boiler though, so it may still require some tweaking. At this stage 8% looks about right though.

 

[RobW]

I don't calculate based on percentage of boil volume. I lose around 10 L in 75 minutes. The major variation is due to how hard I boil.

[post="96272"][/post]​

About the same for me

 

[Guest Lurker]

Someone out there has a lot to answer for, whoever started the idea that evaporation should be defined as a percentage of volume. Evaporation is pretty much independent of volume! Evaporation is a function of
1) Vigour of boil
2) Area of kettle opening
3) Ambient humidity in the air above the kettle
4) How much wind is around and how often the air above the kettle gets replaced by new air.
So the replies that give a percentage are no use to you unless you also know their batch volume to work back to the evaporation rate!

I do either 20 l or 45 l batches. Evaporation in l/hour is essentially the same in each case. As a percentage obviously totally different.

To answer the question
6 l/hr from a four ring burner
8 l/hr from a NASA

 

[T.D.]

I agree GL, that's why all my figures went out the window when I got my new boiler (it has a bigger opening for starters). But having said that, it appears that most brewing software packages require a % figure for the equipment stats, Beersmith certainly does anyway. I wouldn't really even be inclined to separate evaporation loss and trub loss myself - if I have a boil volume of 30L and I collect 23L, I am happy to conclude that my losses are 7L, and that's that. Losses to trub also change from batch to batch (depending on the amount and type of hops you use for example).

 

[Aaron]

I do either 20 l or 45 l batches. Evaporation in l/hour is essentially the same in each case. As a percentage obviously totally different.

[post="96281"][/post]​

That is interesting. I had not heard or considered that before. I think I will do some research/testing on that. I allways do the same size batches so have not noticed that effect.

Thanks for the info.

 

[SteveSA]

I'm with GL and prefer L/hr rather than percentage. It's common sense really.

Unfortunately, Beersmith only caters for a % value, whereas Promash allows for either method. No big deal to correct it though since it calculates the boil off in your equipment profile.

On a 60min boil I lose 4L evaporation but for a 90min boil I lose an additional 0.5L (total 6.5L). I'm not 100% sure why the extra 0.5L evaporates but it's consistent so I'm happy with that. Maybe my 90min boils have been on dry days?

Steve