I just cant get this right....

Crookedeyeboy

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What part of the software controls by how many degrees your wort will increase in a set period of time.What ever recipe I seem to dial in, the difference between the pre-boil gravity and the post boil gravity are always miles off.

I did a Heady Topper clone last night and I wanted 1.047° per boil, I actually got 1.050° so I was a happy chap.
90 minute boil with two really good powerful elements and an average of 8 lts an hour boil off got me to 1.065° when the recipe editor said I should be up at 1.077°, that's a whopping 13° out!

Maybe I have missed something here or got the figures dialed in wrong but if someone can point me in the right direction I would be grateful. I have reduced my efficiency down to 70% due to this inaccuracy but I must be able to sort this out somehow?

Thanks in advance!
 
I just had a similar problem in a Pliny clone yesterday. You ever figure it out?

My refractometer was off by .3 brix for preboil after I checked calibration but that's not even a point and I missed postboil OG by 9.
 
I changed my settings so that I use both elements in my boiler during the boil
I am now constantly hitting just above my target OG's and have upped the efficiency a little
 
first the pre boil gravity is just an estimate not at all 100% accurate, it really depends on how much you sparge and your water amounts, 1 or 2 points off is good, also when you pull your wort and sparge water in the boil kettle do you stir it before you boil
 
Im not sure how the editor accounts for hop displacement, meaning if I put 3 pounds of hops directly in the boil and you use a bag, the displacement will be different throwing the starting gravity off and it will also be different compared to a pilsner less hops, maybe that should be looked at.

or you can set up a profile just for very hoppy beer and set the hop utilization higher in the profile
 
For what it's worth I spoke to the owner of my LHBS and he had a similar problem a few years back. He ended up emailing Jamil Zainasheff and let me read the response.

He basically said that one of our readings had to be wrong. That is, we screwed up measuring pre-boil gravity, pre-boil volume, post-boil gravity, or post-boil volume. The formula used for how the gravity concentrates as wort boils off is solid so we took a reading wrong somewhere. I don't believe Jamil walks on water but so far his advice has worked for me and I've certainly made mistakes in brew days before. I'm guessing I didn't stir my boil pot as much as I thought after draining the sparge on top of first runnings.

I'm thinking I need to brew a session beer soon (low potential $ loss if I mess up again) but this time taking multiple reading at each stage and maybe using my aeration drill attachment to mix the wort before taking a pre-boil gravity. If I'm within 2 points I'll be happy. I've got an Enjoy By Clone recipe in the chute and all the expensive New Zealand hops for it - don't want that one to fall flat.
 
first the pre boil gravity is just an estimate not at all 100% accurate, it really depends on how much you sparge and your water amounts, 1 or 2 points off is good, also when you pull your wort and sparge water in the boil kettle do you stir it before you boil

I have never come close to getting pre boil gravity close to recipe est.in BF.though my pre boil volume was as predicted. It seems that it will not take into account my boil off amount in my profile which is set to .5gal but rather uses something close to 1.5 gal. If you back calculate from your ending kettle volume gravity you will find how far off the estimate is. I find 7-10 points off. Noit good and not usable. I will use the volume/gravity calculating tools frome now onto arrive at my own estimate.
 
preboil gravity also relies on your mash efficiency, not brewhouse and this can vary no fault to the software, if you have a low mash efficiency it throws everything off
 
preboil gravity also relies on your mash efficiency, not brewhouse and this can vary no fault to the software, if you have a low mash efficiency it throws everything off

My mash efficiency is very good, 80-83% and my preboil is probably where it should be and not mess with it as it is always higher than estimate. Brewhouse eff is set to 75%. Playing with the Builder some more i found that an original recipes estimate seems reasonable say for a 5.25g batch it was 10 points difference. however when i scaled to 3 gal batch the preboil went to 16 points off. 1.042 for an OG of 1.058. Scaling may be the problem and I scale alot.
 

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