Author Topic: Boil volume not changing when boil length changed.  (Read 15238 times)

Offline ivectoryou

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Boil volume not changing when boil length changed.
« on: June 11, 2011, 01:25:20 PM »
With BeerSmith 1, the boil volume would automatically change when I changed the length of the boil.  This was obviously due to factoring in more evaporation.

With BeerSmith 2, the boil volume does not change when I change the length of the boil in a recipe.

I'm sure the mistake is mine and if you can inform me of how to fix this issue, I would really appreciate it.

Thanks in advance!

P.S.  Loving BeerSmith 2 so far.  Everything I have seen I really like.

Offline Pat

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Re: Boil volume not changing when boil length changed.
« Reply #1 on: June 11, 2011, 03:58:45 PM »
[EDIT: Just realised I misread ivector's question. I've corrected this in a later post. ivektoryou's question was about time not batch size as I answered here sorry.]

Hi there Ivector,

This is actually an improvement. The actual volume loss to evaporation is mainly dependent on the surface area of your wort. For example, I do both single and double batches in my 18.5 Gal (70 L) kettle.

If I do a 90 minute single batch my evaporation is approx 7 L = about 18% per hour.
If I do a 90 minute double batch my evaporation is approx 7 L =  about 10% per hour.

So, the percentage varies as your batch size changes but not the actual volume lost. All is good and in reality this works well given the same atmospheric conditions during the boil.
« Last Edit: June 12, 2011, 05:26:22 PM by Pat »

Offline BeerSmith

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Re: Boil volume not changing when boil length changed.
« Reply #2 on: June 11, 2011, 07:33:32 PM »
This has been a debate for some time (going back to 2003 if I recall) - but a lot of people wanted the boil losses to be constant so I went with that on BeerSmith 2.

I believe the population that would like it one way or another are about 50-50.

Brad
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Offline ivectoryou

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Re: Boil volume not changing when boil length changed.
« Reply #3 on: June 12, 2011, 10:38:40 AM »
Thanks Pat and Brad!

Now that I know that it was intentional and is likely very accurate, I am a happy camper.

I am brewing 10 gallons today.  I loaded the recipe in BeerSmith 1 and BeerSmith 2.  It will be interesting to see what my actual losses are using a 90-minute boil and compare those to a future or past 60-minute boil. 

Thanks for the quick replies!

Now out to brew that first ever Kolsch!

Offline RJKSKI

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Re: Boil volume not changing when boil length changed.
« Reply #4 on: June 12, 2011, 12:12:01 PM »
I'm confused. I always make a 5 gallon batch. Some I boil for 60 minutes, some for 75 and some for 90. I always used a 15% evaporation rate and it was dead on for my starting boil volumes. Is there anyway to use percent evaporation instead of a set boil off amount. This does me no good whan I cange my boil time. It somewhat defeats the purpose of using software to calculate boil volumes. Can you make it so the user can select one or the other depending on preference? Frustrated!
« Last Edit: June 12, 2011, 12:14:17 PM by RJKSKI »
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Offline Pat

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Re: Boil volume not changing when boil length changed.
« Reply #5 on: June 12, 2011, 05:10:04 PM »
Whoops, I misread your first post sorry ivectoryou and gave you the right answer to a question you actually didn't ask  ::).

Yes, the evaporation volume shouldn't change between a single and a double batch of the same boil length...

BUT

It should change with different boil lengths of the same batch size.

I'm guessing the correcting of the batch size problem mucked up the time side of things.

A temporary fix would be to create a different profile for each boil length.

Cheers,
Pat
« Last Edit: June 12, 2011, 05:16:52 PM by Pat »

Offline RJKSKI

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Re: Boil volume not changing when boil length changed.
« Reply #6 on: June 13, 2011, 02:52:45 PM »
So has it been dcided that this is a bug that needs to be fixed?
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Offline daveotero

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Re: Boil volume not changing when boil length changed.
« Reply #7 on: June 13, 2011, 04:21:43 PM »
I think what would be most useful is a fixed amount boil off per hour.

The percent per hour from v1 never made much since to me because the boil off is more a function of kettle configuration and ambient conditions than the amount of liquid in the kettle. I had to make separate equipment profiles for different batch sizes. I, for example, have a very low boil off rate and only lose 1.12 gallons for a 90 min boil, for any batch size. If I were able to set a rate of 0.747 gal/hour the calculations would always be correct regardless of batch size and boil length.

Sound right to anyone else?

-Dave

Offline Yeasty

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Re: Boil volume not changing when boil length changed.
« Reply #8 on: June 13, 2011, 07:06:55 PM »
Yup. At least on the scale we brew, it makes more sense to have a qt/hr boil off constant.

Offline ivectoryou

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Re: Boil volume not changing when boil length changed.
« Reply #9 on: June 13, 2011, 10:32:37 PM »
Whoops, I misread your first post sorry ivectoryou and gave you the right answer to a question you actually didn't ask  ::).

Yes, the evaporation volume shouldn't change between a single and a double batch of the same boil length...

BUT

It should change with different boil lengths of the same batch size.

I'm guessing the correcting of the batch size problem mucked up the time side of things.

A temporary fix would be to create a different profile for each boil length.

Cheers,
Pat

Thanks Pat!  That makes a lot more sense.

Offline RJKSKI

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Re: Boil volume not changing when boil length changed.
« Reply #10 on: June 18, 2011, 07:59:17 AM »
I'm still not getting this. If I change my boil time, with everything else being equal the amount of wort I need to start with to end up with 5 1/2 gallons changes. Whether you calculate by % evaporation rate or gallons per hour boiled off. I will still need to start with about 8 gallons for a 90 minute boil versus 7 gallons for a 60 minute boil to end up with 5 1/2 gallons in the boil pot and this is not happening in version 2. No matter what boil time I set. B.S. 2 tells me to start with 7 gallons. Even if I set it for 10 hours I need to start with 7 gallons. Maybe I have something set wrong. Not sure.
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Offline BeerSmith

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Re: Boil volume not changing when boil length changed.
« Reply #11 on: June 18, 2011, 10:49:09 AM »
Hi,
  This has been a controversial issue - a large group of people wanted the boil volume fixed as it was too hard to readjust their equipment every time the boil volume changed (so I changed it to boil off volume).

  Now there is a large group who want it the other way (boil off rate) -- so I guess what I'm going to have to do is support both options. 

   I'll go back into the program and add a checkbox so you can enter either one (either a boil off fixed volume or a rate such as gallons/hour).  That way everyone will be happy.

Brad
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Offline CadKing

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Re: Boil volume not changing when boil length changed.
« Reply #12 on: June 18, 2011, 01:50:52 PM »
Thank you Brad... thats very much appreciated at least from this beginner brewer.

It is great to see the way you support the users of the program.

Offline Thepearsonfam

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Re: Boil volume not changing when boil length changed.
« Reply #13 on: June 20, 2011, 11:25:21 AM »
This was the first issue I noticed on 2.0 too.  I liked setting my boil-off rate (v 1.4) for my equipment since the rate is consistent, regardless of boil time or boil volume. I simply set my rate at 17% for my converted kegs and hit my target every time, regardless of 5/10 gal batches or 60/90 minute boils.  I also did the 'work-around' by making two equipment profiles but I would greatly appreciate the option like v 1.4 offered.

Thank You. I really like the interface.

sincerely, Rob

Offline Pat

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Re: Boil volume not changing when boil length changed.
« Reply #14 on: June 20, 2011, 01:16:35 PM »
The only thing Brad needs to fix with the current formula is the time factor. This is not a percentage issue.

Evaporation from two bodies of water of the same surface area is the same regardless of the volume of that body of water. (Just imagine a lake or reservoir - the same gallons/litres evaporate off the lake on average each day regardless of whether it is nearly full or nearly empty.)

BeerSmith 2.0 is working on a fixed boil off volume regardless of batch size. This is correct.  What isn't happening though at the moment is that time is not being taken into account. e.g. If the boil off is 1 gallon per hour, it is not being multiplied by 90/60 for a 90 minute boil. Simple as that.

Working on percentages will get you in the ball park for brews of the same batch size of boil lengths varying from 60 to 90 minutes (the difference is only a few quarts) but the calcs will still be wrong. This error increases when the batch size is doubled.

It is common for people expecting a result from a brew sheet to dismiss any discrepancies. The fact is that boil off on single batches in small diameter pots will vary by less than 1.5 quarts/litres between a 60 minute and a 90 minute boil. Measuring / noticing a small difference like this is difficult especially given brews with different hop bills etc. This also assumes constant atmospheric conditions but in reality...

Boil off almost always varies from brew to brew due to atmospheric conditions. Cool, calm, humid conditions provide for least evaporation whilst hot, dry windy conditions will give the most.

So BeerSmith2.0 does not need to provide two alternate methods, it just needs to add the time factor then everything will be correct.

Cheers,
Pat