Beersmith - Pre-boil Gravity and OG

[Miles_1111]

I have brewed around 10 batches with the help of Beersmith, then I found a problem about the equipment that I added:
On average of the 10 batches, the Est OG is 4p higher than the Est Pre-Boil Gravity. However, on average my Measured OG is only 3p higher than my measuread Pre-Boil Gravity. This casues my that I can reach the Est Pre-Boil Gravity most of time, but I could not never reach the Est OG.

Is this because of anything wrong with my equipment set up in Beersmith? If yes, how can I change it?

Thanks.

 

[Oginme]

If you are reaching your pre-boil gravity pretty close from your mash, then the boil off losses you have in your equipment profile is incorrect. You should also see this in your volumes pre-boil versus post-boil, if you water balance is close to correct for other losses.

The most accurate way of correcting this is with your volumes and calculated boil off rate. Since you already know the gravity point difference is only 75% of your current expected value, you can start by estimating the boil off rate is off by the same ratio.

 

[Dcpcooks]

I agree with boil off as mentioned above.

The fact that Your OG is higher than estimated implies your efficiency is a touch better then you have set up.

 

[FunkedOut]

in order to evaluate how close your equipment profile emulates your rig, you need to have the volumes and the sugars.
you've only given us half the picture.
how are the volumes?

 

[Miles_1111]

If you are reaching your pre-boil gravity pretty close from your mash, then the boil off losses you have in your equipment profile is incorrect. You should also see this in your volumes pre-boil versus post-boil, if you water balance is close to correct for other losses.

The most accurate way of correcting this is with your volumes and calculated boil off rate. Since you already know the gravity point difference is only 75% of your current expected value, you can start by estimating the boil off rate is off by the same ratio.

I agree with you, but I took a look at my settings, still don't have a clue how to adjust it. Here I attached a pic of my set up. Could you be specific how I can get started to correct it? Cheers man.

 

[Miles_1111]

in order to evaluate how close your equipment profile emulates your rig, you need to have the volumes and the sugars.
you've only given us half the picture.
how are the volumes?

Please see my set up in the above reply.

 

[Oginme]

OK, working from the equipment profile and the information in your original post:

You are starting with 13.89 l having a gravity of around 10.8°P which after a boil off gives you 13.8°P. If your actual finishing gravity was estimated to be 14.8°P with a 3.75 liter boil off, you can calculate an estimated boil off by the resultant gravity after boil. Thus 13.89 liters at 10.8°P has a sugar content of around 150 [10.8 * 13.89]. Your ending gravity is 13.8°P and since no sugars are lost to the boil, your resultant volume should be around 10.87 liters. This gives you a boil off of around 3.02 liters for 90 minutes.

I would also recommend entering the boil off rate as an hourly rate, otherwise BeerSmith figures your boil off to be an absolute value which is fine if you don't change anything, but changes in boil time will not be accurately reflected in the modelling of your system. You can calculate this by taking your 3.02 liters and dividing it by 1.5 hours to get 2.01 liters/hr.

I think I was correct in calculating your starting gravity, but if I was off you can just plug the actual number into the calculations to correct it.

 

[FunkedOut]

Please see my set up in the above reply.

Sorry bud, I should’ve specified I was referring to the measured volumes that go along with your measured gravities.
A screen shot of your sessions tab would do it.

 

[Miles_1111]

OK, working from the equipment profile and the information in your original post:

You are starting with 13.89 l having a gravity of around 10.8°P which after a boil off gives you 13.8°P. If your actual finishing gravity was estimated to be 14.8°P with a 3.75 liter boil off, you can calculate an estimated boil off by the resultant gravity after boil. Thus 13.89 liters at 10.8°P has a sugar content of around 150 [10.8 * 13.89]. Your ending gravity is 13.8°P and since no sugars are lost to the boil, your resultant volume should be around 10.87 liters. This gives you a boil off of around 3.02 liters for 90 minutes.

I would also recommend entering the boil off rate as an hourly rate, otherwise BeerSmith figures your boil off to be an absolute value which is fine if you don't change anything, but changes in boil time will not be accurately reflected in the modelling of your system. You can calculate this by taking your 3.02 liters and dividing it by 1.5 hours to get 2.01 liters/hr.

I think I was correct in calculating your starting gravity, but if I was off you can just plug the actual number into the calculations to correct it.

Thanks all that. I did math about my 10 batches based on the fomula you showed: Pre-boil Volume * Pre-boil gravity = Post-boil Volume* Post-boil OG. The result is my average boil off for 90 mins is 3.08L, which is 2.05L lost for hourly lost as blow:

Hope this can help me to get rid of of the problem. Thank ya'all

 

[kevin58]

Have you customized your profiles? The equipment and mash profiles in Beersmith are good starting beginnings but they are based on someone else's exact measurements. Yours will be different. As mentioned your boil off rate will be different. So will your losses in various places.
Marshall at Brulosophy has posted profile setup videos that are easy to follow. Here is one on equipment but he also has some posted for mash profiles...

It is very important to have accurate profiles set up to get accurate results from the software.

 

[Miles_1111]

@Oginme I just created a new receipt by using the adjusted equipment profile which I posted in previous reply. However, my original problem of this post has not been changed, as the difference between Est OG( 1.069 ) and the Est Pre-Boil Gravity(1.051) is still around 4p..

It seems the result won't change much even if I have changed the equipment set up.. Maybe I am wrong?

 

[Miles_1111]

Or should I adjust the Evaporation rate to 13.5%hour? Because this is 3/4 of my original set up which is 18%hour Evaporation rate, but if I do this, the boil off will be around 2.6L which is different from the average result (3.08L) I calculated from previous batches . Which way is correct or I was wrong with any point? Thanks.

 

[FunkedOut]

If you modify your equipment profile in the equipment profile tab, it will not update the equipment profile in the recipe and vice versa.
Do you have it correct in both places?

 

[kevin58]

If you modify your equipment profile in the equipment profile tab, it will not update the equipment profile in the recipe and vice versa.
Do you have it correct in both places?

If you change any of your profile settings does nothing to existing recipes you have saved. If you want those previously saved recipes to have the new profile settings you will need to open the recipe... and then change the equipment or mash profile to the new one (even if it's the same file with revised data) and re-save your recipe.

 

[Oginme]

As Kevin58 stated, if you adjust your equipment profile outside of the recipe, you will need to update the recipe with the new profile to have the changes reflected. BeerSmith treats each recipe as a separate 'archive' so that changes you make later will not affect the actual targets and results of your previously brewed recipes. To track this, I add the date of the last change to my equipment profile so that when I open a recipe from my recipe folder, I can tell at a glance if the profiles need updating.

 

[FunkedOut]

I prefer not to update old recipes that have already been brewed.
I always make a new copy of the recipe and update the profile there.
That way you can keep all of your session tabs and have a history of all things.

 

[Smellyglove]

Are you 100% sure that your volume measurements are correct?

Pre chill?

Whenever I feel like I have to tweak my boiloff I do a 90 minute boil and measure when it starts to boil, and after 60 minutes again. Measuring at the same temperature is pretty important, but I guess you know, and do this.

 

[Miles_1111]

@FunkedOut @[URL='https://www.homebrewtalk.com/forum/members/kevin58.246742/']kevin58 @[URL='https://www.homebrewtalk.com/forum/members/oginme.155764/']Oginme I did re-add the adjusted equipment to the previous recipes, the pre-boil gravity changed a little bit, but not much, the difference is still around 4p, a little be better though. In fact, I created a new recipe and used the modified equipment profile, and again is around 4p...[/URL][/URL]
Anyway, I am brewing a new batch this weekend and will let you know how it goes.

 

[Miles_1111]

Are you 100% sure that your volume measurements are correct?

Pre chill?

Whenever I feel like I have to tweak my boiloff I do a 90 minute boil and measure when it starts to boil, and after 60 minutes again. Measuring at the same temperature is pretty important, but I guess you know, and do this.

I am pretty sure the pre-boil volumes are correct, but by my equipment I could not measure the after-boil volume, so I did not. However, I can use the fomula to calculate the after-boil volume which I believe is correct. I have paid attention to measure the gravities at the same tempeture 20 C. I will make it will be very precise in the future.

 

[FunkedOut]

The problem with using gravity readings to calculate volumes is that any error in gravity measurement gets carried over.
Measuring both will give you a cross check.
It is possible that poor mixing of the mash will lead to higher or lower gravity reading than would be measured if the solution was homogeneous.

Etch you pot or mark a stick so you can consistently and accurately measure volumes in your kettle.
Measure volumes pre and post boil for all your brews.
I found that a water boil off test gets you close but boil intensity matters.
I was not good at matching the otherwise repeatable boil intensity of my brews when I did a water test for my new kettle.

Over the course of a few brews, you'll walk it in. Progress, not perfection.
Took me a water test and 2 brews. 3rd time was a charm.

 

[FunkedOut]

Another thought...
If you overestimate your boil off rate, you'll end up with a watered down beer, unless you boil longer, which leads to more color and bitterness than planned.
If you underestimate your boil off rate, you'll end up with a more concentrated beer, easily remedied with a measured pour of sterile water.

 

[Smellyglove]

I agree with the person above saying you need to also measure your post boil wort. It might be as simple as a non-linear scale on the hydrometer, or something else strange.

 

[Miles_1111]

@FunkedOut @Smellyglove
Any idea how to better put mark on the stainless steel boiling kettle? I assume any sticker inside will be boiled off... or should I measure it after transfered into the fermenter? Thanks.

 

[FunkedOut]

@FunkedOut @Smellyglove
Any idea how to better put mark on the stainless steel boiling kettle? I assume any sticker inside will be boiled off... or should I measure it after transfered into the fermenter? Thanks.

https://www.homebrewtalk.com/forum/...lume-markings-to-a-kettle-illustrated.463099/

 

[Miles_1111]

Update from my last Saturday batch. Pre-boil OG is 13.33P and the after is 17p, which gives the difference is 3.67p. It is between 3p and 4p... anyway, guess I will get started to measure the after-boil volume! Thanks guys