Getting the Numbers right.

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Dan Pratt

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Ive been brewing on the BM for a couple of years now and after looking at my records Im always either over or under on final volume n( depends on hop bill and style) and ALWAYS below Target Gravity.

I have it set for 65% Brewhouse efficiency and have no worries getting 85%+ from a mash eff. Sure i can just make the beer and go ok, thats my system but I think my boil is effecting the end gravity, the BM's are by no means vigourus and they tend to boil on one side of the kettle where the 3 heat elements are in line ( its a loop and on one side its 2 and teh other its 3 )

Ive been through about a dozen online calcs and done my own math and somehow my system or something is dragging the chain. I use BS 2.0 and from reading online the math is 1GP achieved during the boil for every 9mins of boiling. I am averaging only 1GP per 13mins of boil.

Having done about 50+ brews on the BM I get on average 7 points for a 90mins boil and only 5 points for a 60min. Im ALWAYS getting a lower than expected Target Gravity and have now idea how to correct this. If I boil for longer it requires more sparge water and that reduces the preboil gravity making the gap even bigger.......

A normal brew with 90min boil:

Preboil Vol = 30.5lts
Preboil Gravity = 1.045
Final Volume = 24.5lts ( minus trub 3.5lts = 21lts into FV)
Target Gravity = 1.055

Required 10 gravity points from the boil and I always go lower, My volume into the FV is +/- 750mls its depends on the amount of hops but the gravity will be 3 points lowere

This weekend is a bigger beer;

Preboil Volume = 34.1lt
Preboil Gravity = 1.075
Final Volume = 27lt ( minus trub 6lts = 21lts into FV)
Expected Gravity = 1.095

That is 20points of gravity from a 90mins boil and I average 7........When doing a bigger beer are the gravity gains during boil higher?

Just cant seem to get it dialled in right :unsure:
 
Was the 1.075 a measured G or is that a predicted?
If you brewed this and got a Preboil G of 1.075 @ 34.1lt and boiled it down to 27lt it should have a G of ~1.095. The sugars are not lost during the boil, just concentrated.
eg. 34.1*75 = 2558 and 27*95 =2565 (pretty close)

So if that is predicted it should be correct.

Are you measuring preboil volume and G?


Note:
When doing a bigger beer like the on you listed I would expect a drop in efficiency. I know both my systems are less efficient when trying to do bigger beers.
You can not expect to get the same efficiency for every OG. I am pretty sure it is to do with the solubility of the sugars and the concentration of the sugars but I am not an expert in the area. I just know it takes more sparge water to wash out all the sugars and hence the longer boil time on a lot of big beers.

I worked out what efficiency I get ~1.050-1.055 since most of my beers are in this range. Then I adjust my expected efficiency with my expected OG (use a bit of guesstimation).
 
Hi RB,

Yep I measure the preboil volume and gravity always to check my numbers and these numbers I can get every brew. So if Im targeting 30.5lts and 1.045, its what I get but the software and calc I have tried all then expect the boil to gain 10 points from a 90min boil. Even when I reduce the boil to 60mins my preboil vol and gravity change and I still hit those numbers. I just cant seem to get 1GP per 9mins from the boil....

I used to run the BM on 75% but that has slowly decreased and its std to have my sytem set on 65%, maybe my boil is effected by the 18mts of immersion chiller that are in there??
 
Um. this might sound obvious, but I'll voice it anyway.

Have you calibrated Beersmith for your evaporation rate?

Default I think it's 9-11%, but I know for my equipment it's 14%. You might have a much lower evaporation rate. Hence the higher volume at the end of your boil.

Just a thought...
 
stienberg said:
Um. this might sound obvious, but I'll voice it anyway.

Have you calibrated Beersmith for your evaporation rate?

Default I think it's 9-11%, but I know for my equipment it's 14%. You might have a much lower evaporation rate. Hence the higher volume at the end of your boil.

Just a thought...
That is one area that I checked recently and filled 31 litres and boiled for 60mins and my boil off is now set at 4Lts per hour which = 6Lts for a 90min boil. ( this I think is about 12.5% per hour or something )

Say it was higher at like 5lts per hour, that would require moe sparge water but would not improve the gain on gravity from preboil to postboil, infact it would make the gap larger as the preboil gravity would be lower due to more sparge water....... :blink:
 
Wait... are you saying that you are getting the correct volume and G pre boil but post boil you are getting the correct volume but not G? This is not really possible.

By the look of what you are saying earlier, it seems that you are not getting as much of a boil off as you had expected.
What volume and G did you end up with post boil in the example you gave?
 
RelaxedBrewer said:
Wait... are you saying that you are getting the correct volume and G pre boil but post boil you are getting the correct volume but not G? This is not really possible.

By the look of what you are saying earlier, it seems that you are not getting as much of a boil off as you had expected.
What volume and G did you end up with post boil in the example you gave?
The volume post boil is hit and miss, within 750ml, it depends how many hops i throw in and dont calculate for. But I always miss the gravity short by 3-4 points. See a wheat beer i made last week was 500mls over target and 3 points short on gravity with a 60min boil. A pale ale i made monday arvo was 1.042 target and i got 200mls over target volume but 1.040 gravity, again short and a 60min boil. I get 5 from 60mins and 7 from 90mins.....

The example was just that, the bis beer is this weekend which is why im trying to nut this out as it expects 20 points of gravity from a 90mins boil....my system only gets on average 7....

Anychance someone can check there records and compare preboil gravity to post boil gravity gains from 60 and 90 min boils?
 
Just a thought.

Are you calculating you post boil volume in the kettle or in the fermenter?
If the volume is in the fermenter then you are not factoring in the wort with the trub still in the kettle. While we do not care much about this volume we do need to include it in the volume/gravity calc.

eg. if you have 27lt in the fermenter but 2lt still in the kettle your actual post boil vol is 29lt. You might not be evaporating as much as you thought if this is the case and your G is therefor not as high as you predicted.
 
Hi Pratty. If you are confident with the boil of rate and you are falling short in terms of SG, then you need to reduce your pre-mash volume or your sparge volume. I personally would reduce the volume of the liquor before you mash in because this shouldn't affect efficiency too much. Do you currently fill to 25L? May be drop this by 10-20%. Have you checked the volume marking are accurate?

EDIT: corrected typo
 
RelaxedBrewer said:
Are you calculating you post boil volume in the kettle or in the fermenter?
If the volume is in the fermenter then you are not factoring in the wort with the trub still in the kettle. While we do not care much about this volume we do need to include it in the volume/gravity calc.

eg. if you have 27lt in the fermenter but 2lt still in the kettle your actual post boil vol is 29lt. You might not be evaporating as much as you thought if this is the case and your G is therefor not as high as you predicted.
RB - got all that covered. My losses to trub are set for 4.5lts due to the hop content and i make that higher when I make my IPA's. The original post was showed post boil volumes including the trub.
 
Black n Tan said:
If you are confident with the boil of rate and you are falling short in terms of SG, then you need to reduce your pre-mash volume or your sparge volume. I personally would reduce the volume of the liquor before you mash in because this shouldn't affect efficiency too much. Do you currently fill to 25L? May be drop this by 10-20%. Have you checked the volume marking are accurate?
Hi, I have played with the numbers and tried reducing the mash volume, that just increases the sparge volume but doesn't change the preboil gravity....the calcs ask for 10points from a 90min boil.

I do a higher volume mash at 28 liters which is measured with a ruler and online volume calc, remove 3 litres, add 5kg malt and add the 3 litres back when the pump gets going, gives me about 10cm of space from the top of the malt pipe.

How may gravity points do you get from preboil to post boil when a 90min boil is done? 5, 7, 12, 15???
 
Pratty1 said:
Hi, I have played with the numbers and tried reducing the mash volume, that just increases the sparge volume but doesn't change the preboil gravity....the calcs ask for 10points from a 90min boil.

I do a higher volume mash at 28 liters which is measured with a ruler and online volume calc, remove 3 litres, add 5kg malt and add the 3 litres back when the pump gets going, gives me about 10cm of space from the top of the malt pipe.

How may gravity points do you get from preboil to post boil when a 90min boil is done? 5, 7, 12, 15???
Hi Pratty,

I have a 50L Brau and haven't been great in keeping records of pre-boil gravities etc. I just used to shoot for a higher gravity and dilute going into the fermenter, so didnt bother taking the roe-boil gravity at all. I now realise that isn't perfect so just started taking more note of my pre-boil gravity and volumes etc. Yes you are right the BM do not give a vigorous boil and consequently the gravity points gained during the boil will be less than other systems. I gained 8 points on a 90 minute boil (n=1, so take it for what it is worth). It just won't give you the 12 points or whatever you are looking for, but who cares. Your brewing software seems to be dictating what you do: it shouldn't, it just an aid: post your equipment profile setting from BS so i can have a gander. Putting the equipment profile setting in BS to the side, if you are constantly getting lower gravity than you want then reduce you mash-in volume and/or sparge volume: just do it, I don't care what BS is telling you, don't listen because it ain't working for you. If I was you I would mash-in with 25L and then sparge with 1L/kg grain. I suspect that will get you closer to your target gravity and then you can make adjustments from there: if you gravity is too high then use more mash-in or sparge water, too low then do the opposite. The only other thing you can do to increase gravity is add more grain, but it sounds like you have a handle on your efficiency so probably unnecessary, or boil longer (which just shouldn't be necessary for an average gravity beer). I hope this makes sense. Give it a try and then look at adjusting your equipment profile setting to match what your doing. Your notes are telling you what you need to do, the brewing software just has not been set up correctly.

EDIT: I just had a look again on your beers. If I was you I would stick to average gravity beers until you get your gravity right. With high gravity beers you will expect to have a lower efficiency. To get a 1.095 beer in a braumeister you should consider doing two sequential mashes with half the grain in each and re-using the mash liquor from the first mash in the second. In this situation I would set my efficiency 5-10% lower, which means you will need more grain to compensate.
 
I also pick up 4-5 points during a 60 minute boil so I target the gravity that much below when the sparge is done and the boil is ahead.

26L to mash with, 7-8L to sparge with and when I have 29L+ (31L max usually) in the kettle and gravity is 4-5 points below the target I stop rinsing.

23.5-24.5L goes into FV.

So for a 1055° beer I would want around 1051° before the boil is on and for a "standard" pale ale malt with degrees litre around 308 ie 1.037 I would use 5.5kg of malt with 78% brewhouse efficiency and 24L brewlength.

I'm never really more than 1 point off on the downside (except with hefeweizens), usually spot on, and rarely 3-4 points above and then I think heck! I could use a stronger beer anyway

To pick up 5 points during a gentle BM boil is absolutely fine and 60 minute boil is fine too. One can measure gravity during the boil a few times and adjust the rate by using the lid: picking up points too slowly, lid off.

Also to add, in my case, I mash and would hit target gravity 1055, sparge and then get 1050, then pick up back to 1055 in the boil.

You also seem to get about 3L less into FV than me.

I brew between 1035 and 1055 without sugar and always use the same mash and sparge volumes and pick up rates seem to be about same.
 
DeGarre - what is your normal grain bill range?
 
If you're consistently getting the same thing then that's a start. If you're under gravity you can either increase your grain bill or reduce your volume. Basically, accommodate by dialing down your efficiency further.
Why not go arse about and target a pre-boil gravity? If you know you're consistently losing x points during the boil then if you sparge to a certain gravity you're guaranteed to hit it.
Then, measure your final volume and put this in beersmith. This should give you an accurate estimate of efficiency BUT I've found that the calculated efficiency differs from what comes out in the grain bill section.
 
lael said:
DeGarre - what is your normal grain bill range?
Not sure I understand the question but I mostly brew between 1042 and 1052, 4.2-5.2kg grain, pale ale, crystal, munich, chocolate, wheat malt being most used malts.
 
DeGarre said:
Not sure I understand the question but I mostly brew between 1042 and 1052, 4.2-5.2kg grain, pale ale, crystal, munich, chocolate, wheat malt being most used malts.
yep - that is it - just trying to figure out your L/Kg sparge water ratio. Thanks!
 

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