Poll: What's Your Evaporation Rate?

[mikem108]

about 6 litres /hour depending on the weather

 

[floppinab]

Depends a lot you kettle setup this one. I've got a relatively short/ squat (just trying to remember the diameter, around 80 odd cm I think) kettle that'll fit around 100L. When I first started full boils I didn't realise just how much water I was losing and how short my post boils were. In terms of the poll I'm well over 20%, probably sitting at around 8L/hour.
No doubt your thinner taller kettles will have significantly lower evap. rates.

 

[mark_m]

I use a cut down 80L keg on a 3 ring burner with variable reg.
Having little surface area, evaporation is only 6-7%/hour (5-6L over an 80min boil - double batch).
I would describe th boil as "gentle rolling" rather than "vigorous".
Generally use a little koppafloc toward the end & have been producing clean, clear beers.
Mark

 

[Steve Lacey]

I have the wood, just waiting for the next brew day

Happens to me sometimes too. Just the thought of getting out all that gleaming stainless.

 

[mckenry]

Would someone mind helping me with beersmith please? It's drivimg me mad.

Here are the statistics for yesterdays brewday.

I collected 45.2L from my mash tun. There was 0.5L liquid in the mash tun at end of day
So pre boil is 45.2L @ 1.045 - 1 hour boil and I'm left with 36.2L @ 1.058 in my 80L kettle.
So 9L boiloff in 80L = 11.25%
There was 2.6L lost to trub & deadspace.

If you see below, it doesnt make sense to me. Why does it say only 4.74L boiloff?? and that the boil volume is only 41.94L ?? I no chill, so I put the chill loss at 0.

Somebody please point out why or where I am going wrong before I bash someone. Only me & the mrs here right now - and it wont be me... :lol: :lol:

 

[mckenry]

Would someone mind helping me with beersmith please? It's drivimg me mad.

Here are the statistics for yesterdays brewday.

I collected 45.2L from my mash tun. There was 0.5L liquid in the mash tun at end of day
So pre boil is 45.2L @ 1.045 - 1 hour boil and I'm left with 36.2L @ 1.058 in my 80L kettle.
So 9L boiloff in 80L = 11.25%
There was 2.6L lost to trub & deadspace.

If you see below, it doesnt make sense to me. Why does it say only 4.74L boiloff?? and that the boil volume is only 41.94L ?? I no chill, so I put the chill loss at 0.

Somebody please point out why or where I am going wrong before I bash someone. Only me & the mrs here right now - and it wont be me... :lol: :lol:

View attachment 26164

After much freaking around & reading here - I have decided I need to leave my evap @ 20% per hour. This way beersmith spits out the right water for me. It may be that my real boiler efficiency is around 11% when done per kettle size, but beersnith definitely works it out as (pre boil volume - post boil volume) / pre boil volume.
exerp from beersmith.com - see here - efficiencies

Evaporation Rate - Enter the percent of wort that boils off in an hour with your system. You can start with 9-10% to get you in the ball park. If you do not know your rate, you can run a test next time you brew - just record the volume at the start of boil and record it again after an hour of boiling. The evaporation rate is:
Evap_rate = 100 * (volume_at_start - volume_at_end)/ (volume_at_end)

So, with all the debate, I will leave it as beersmith intends and it will be all good as long as I keep doing similar sized batches.
If I go a bit under or a bit over - so what? It'll be good enough for the home environment. :beer:

 

[Stuster]

So pre boil is 45.2L @ 1.045 - 1 hour boil and I'm left with 36.2L @ 1.058 in my 80L kettle.
So 9L boiloff in 80L = 11.25%

It seems like you've worked it out, but really the 80L is the volume of the kettle , not the volume of liquid you have in it which is what you are evaporating from. So 9L out of 45L is 20%. Set that as your evaporation rate. Also, you can set your final volume there to 36L.

In fact, the evaporation won't really change even if you do a bigger/smaller batch as it's dependent on the surface area rather than the volume underneath it, but as you say it'll do for the homebrew level. Once you know your system you know yourself how much you will boil off and can calculate water additions based on that rather than on what Beersmith says.

 

[mckenry]

It seems like you've worked it out, but really the 80L is the volume of the kettle , not the volume of liquid you have in it which is what you are evaporating from. So 9L out of 45L is 20%. Set that as your evaporation rate. Also, you can set your final volume there to 36L.

In fact, the evaporation won't really change even if you do a bigger/smaller batch as it's dependent on the surface area rather than the volume underneath it, but as you say it'll do for the homebrew level. Once you know your system you know yourself how much you will boil off and can calculate water additions based on that rather than on what Beersmith says.

Yeah, I only posted this up as most experienced guys say that evap rate can only properly be expressed as a L/hour figure, not a %. Most will boil off (for e.g.) 9L/hour regardless of whether the start volume is 40L or 60L. Therefore the evap rate will be different depending on different start volumes (doing it the way beersmith likes it). BUT, if you always boil off 9L reagrdless of batch size, the 9L/hour per boiler size remains constant. Hope I've explained this well enough :huh:

 

[buttersd70]

Mckenry
even though you No Chill, you would still have loss to chilling...it's just that it takes overnight instead of 20min The chill loss is due to the liquid contracting as it cools....

Just to complicate things further.....

As far as the loss to trub setting, there has been a bit of discussion about that setting for a long time....if you enter the loss there, beersmith has a glitch that throws the hopping out. It doesn't recognise that the 2.6L (or whatever amount) left in the kettle is hopped. (ie it somehow imagines that all of the isomorised alphas make it out of the kettle, instead of being distributed between what goes out of the kettle, and what stays in the kettle, if you know what I mean...)...so, many people get around this by setting this loss to 0, and increasing the batch size by the relevant amount.

 

[flattop]

Around 2L an hour in a narrow urn which is under 10% but i haven't yet achieved the kind of boil i want.

 

[mckenry]

Mckenry
even though you No Chill, you would still have loss to chilling...it's just that it takes overnight instead of 20min The chill loss is due to the liquid contracting as it cools....

Just to complicate things further.....

As far as the loss to trub setting, there has been a bit of discussion about that setting for a long time....if you enter the loss there, beersmith has a glitch that throws the hopping out. It doesn't recognise that the 2.6L (or whatever amount) left in the kettle is hopped. (ie it somehow imagines that all of the isomorised alphas make it out of the kettle, instead of being distributed between what goes out of the kettle, and what stays in the kettle, if you know what I mean...)...so, many people get around this by setting this loss to 0, and increasing the batch size by the relevant amount.

ahh butters... geez man, I thought I had it nailed... Yeah, thought about the chill loss, but decided it wasnt a big enough loss to bother with.
As for the trub loss - thanks for the info and will adjust accordingly.
Out of interest, how much IBU are we talking when beersmith ignores the trub volume when calculating IBU? If I have designed a recipe at 25IBU then in reality I'll get ???? My guess is this - 2.6L out of 36L is roughly 7.5% so is beersmith underestimating by 7.5% ? or giving me +7.5% in those 36L collected?
cheers butters
mckenry

 

[buttersd70]

the difference it makes is that if you have 2.5L trub loss, and 25L to the fermenter (for easier amounts, for the sake of discussion), the IBU needs to be calculated with 27.5L in mind (25L hopped wort to fermenter, 2.5L hopped wort, trub and crap left behind)....but beersmith doesn't, it ignores the trub amount, and works it out as 25L volume only, so it would be.......under. Underestimating the IBU is the magic direction. (had a few, and needed to vocalise it to remember which way it was. :lol: )

 

[mckenry]

had a few, and needed to vocalise it to remember which way it was. :lol:

yeah me too :lol: thought it would be under estimating. So I need to go for a 38.6L batch when I want to collect 36L, leave losses to trub at 0 and I will get the right IBU for the collected amount.

Is this a problem when converting other peoples recipes? As I said, had a few :lol: and its getting hard to think this out

 

[mckenry]

By the way, does Promash have these problems?

 

[Screwtop]

Evaporation percentage rates don't work. Boiloff rate for my system is usually 6L per hour.

Screwy

 

[buttersd70]

By the way, does Promash have these problems?

I don't believe so....

Conversion of other peoples recipes is always a bit of an issue; certain assumptions need to be made. Although, even if the same brewing software is used (and to take it one step further, even if the same equipment is used) there will be a certain amount of difference from one brewers technique to another. I know that, for example, DrSmurtos Golden Ale varies from brewer to brewer, even if they remain faithfull to the recipe and don't tweak it. I've had a few of these, brewed by several different people, and all are subtley different. The main point is to get consistency with your own gear, and make any adjustments from there....

On a slightly more dificult conversion, is taking someones promash recipe and converting into beersmith (or vice verca). There are quite a few differences in the programming, the main one being, imo, in relation to the baseline calculation for the hopping.....promash uses whole hops as it's default, and makes adjustment for pellets; beersmith does it in the opposite direction, uses pellets as it's defaults, and adjusts for flowers. You wouldn't think that this makes much of a difference; but it does. Having crunched th numbers over a range of recipes, I've found that the overall utilisation in beersmith needs to be set to 111% hop utilisation factor, in order for the IBU to match point for point in identical recipes...(in other words, instead of 90% utilisation for flowers, you increase it to achieve an equivilency of 100%, ie 90% x111%). In the course of most "general" recipes, it doesn't make a hell of a lot of difference. What's a couple of IBU between friends when it's an APA with 40IBU to begin with? It's a small fraction......but when I went AG, I set myself a hard task, to force myself to conform to a certain degree of precision....that is, brewing Milds. The tolerences are much lower in a 1035/17IBU mild than they are in a 1050/40IBU APA. The small, seemingly insignificant differences, stick out like a third wossit on a dog....But, as said, the most important thing really is to get consistency on your own rig. The numbers themselves then become somewhat meaningless, because you are then aiming for the range that you want based on your own calculations, to your own experiences, on your own equipment.

(actually, a good example of the IBU issue in beersmith can be seen in the recipe database, which afaik gives a result closer to that of promash. If you have a look at DrSmurtos recipes, it has the IBU that was calculated with the database software; in the notes, he has been kind enough to state what Beersmith gives as the IBU.......do a quick bit of math, and you see it's very close to 111% varience.)

Whoops....marginally OT. Sorry. B)

 

[mckenry]

Evaporation percentage rates don't work. Boiloff rate for my system is usually 6L per hour.

Screwy

Hey Screwy. See post #29, (mine above). I know they dont really work properly, but as far as beersmith goes, how else will I get my water volumes right? Do you think %s are OK if I always aim for the same post boil volume?
Thanks,
mckenry

 

[flattop]

Oops i didn't include the trub in mine but i estimate the trub to be around 1/2 a litre, i whirlpooled the urn and the crown has an element cover in the center that all the trub material seemed to cling to, i was able to tilt and drain almost all the wort out.

 

[crundle]

I lose around 7.6% per hour in my Crown urn with the lid off for the boil outside in Autumn. Not sure how it will change with the seasons but seem to think that it will. Probably aournd the same loss to trub as flattop at around 0.5-1 litre.

Crundle

 

[raven19]

Second AG, we lost 5L or 7% of preboil volume in a 60min boil.
Trub losses depend on amount of hops we use, as we tip the kettle to capture maximum wort possible without break/hops.