Who to trust?

[MrJay83]

Got a AG kit and the OG was specified at 1.075 @75% efficiency. Plugged the figures into Brewers Friend and it showed 1.062 @75%.
I'm relatively new to AG and just wondering what people's opinions are. It seems a pretty wide difference.

 

[YeastFace]

Brewers Friend is Brewhouse efficiency, the one given on the kit may be mash efficiency?

 

[MrJay83]

To be fair it doesn't say which one on the sheet and I tried the different stage options on the BF calculator but it still doesn't match up. Not even close.

 

[Sandimas]

Welcome to the minefield of AG kit brewing.

Unlike malt extract kits, the OG of an AG kit where a mash is involved is only an approximation because everyone has different equipment and brewing methods. Added to that, different manufacturers use different efficiencies when coming up with their recipes - some use 70%, some 75% (the Brewers Friend default), etc.

So take any quoted AG with a pinch of salt. You can only be sure of the OG when you spec your own recipe based on your efficiency e.g. mine is consistently 68%, so I need a bit more grain if using a kit to hit the target OG. I don't tend to buy AG kits for this reason.

 

[MrJay83]

Welcome to the minefield of AG kit brewing.

Unlike malt extract kits, the OG of an AG kit where a mash is involved is only an approximation because everyone has different equipment and brewing methods. Added to that, different manufacturers use different efficiencies when coming up with their recipes - some use 70%, some 75% (the Brewers Friend default), etc.

So take any quoted AG with a pinch of salt. You can only be sure of the OG when you spec your own recipe based on your efficiency e.g. mine is consistently 68%, so I need a bit more grain if using a kit to hit the target OG. I don't tend to buy AG kits for this reason.

Sorry, I think you are getting me wrong. They are stating an efficiency and an OG. I'm plugging the exact grain bill into BF and getting totally different figures. I probably get about the same efficiency as yourself so I always keep that in mind. My gravity vs what the kit says is not what I'm asking.
I'm hoping this doesn't come across as snarky.

 

[MrJay83]

Welcome to the minefield of AG kit brewing.

Unlike malt extract kits, the OG of an AG kit where a mash is involved is only an approximation because everyone has different equipment and brewing methods. Added to that, different manufacturers use different efficiencies when coming up with their recipes - some use 70%, some 75% (the Brewers Friend default), etc.

So take any quoted AG with a pinch of salt. You can only be sure of the OG when you spec your own recipe based on your efficiency e.g. mine is consistently 68%, so I need a bit more grain if using a kit to hit the target OG. I don't tend to buy AG kits for this reason.

I'd agree with you that I'm starting to move into making my own recipes... Baby steps

 

[Agentgonzo]

If two sources of information don't agree, seek a third.

Try a third tool like brewfather or post the recipe in here for someone else to see what they estimate the OG to be.

 

[MrJay83]

Don't want to put the whole thing here in case someone gets the hump but my OG has just come out at 1.062. bang on BF prediction and 13 points off the kit gravity prediction at the same listed efficiency.
Hence my question... What do people usually trust? Something like BF or what the kit suppliers say?

 

[Clint]

Volume?

 

[MrJay83]

Volume?

25lt into the fermenter. 8.2kg grainbill, split between two mashes because I'm using a 35lt brewzilla.
Interestingly I just seen in another thread that someone done this in one mash with good results.

 

[MickDundee]

25lt into the fermenter. 8.2kg grainbill, split between two mashes because I'm using a 35lt brewzilla.
Interestingly I just seen in another thread that someone done this in one mash with good results.

Was the kit definitely for 25L into the fermenter? Most are 20L or 23L aren’t they? Might explain some of the difference in OG.

 

[Nottsbeer]

Don't want to put the whole thing here in case someone gets the hump but my OG has just come out at 1.062. bang on BF prediction and 13 points off the kit gravity prediction at the same listed efficiency.
Hence my question... What do people usually trust? Something like BF or what the kit suppliers say?

Could you put a link for the kit and instructions. It may help to offer insight into what has gone wrong...if anything.

 

[Slid]

The efficiency sweet spot for the Grainfather is 4.5kg grain bill. This is proven to be a fair evaluation from my 200 or so uses. I cannot imagine an A-I-O system of 30L capacity being much different. An 8.2 kg grain bill is possibly best approached by either of two methods:

1. Parti-gyle - where you do a full volume first mash and take out say 12L of wort and boil that separately with hops for your strong beer. The volume taken is replaced by water at 65C to do a second mash. This maybe around 30mins and could be "capped" by adding the Crystal and other non-mash malts at this stage, just as if it were a normal brew.

2. Doble-doble - you mash with half the grain bill, sparge it a bit and use the wort produced to be the "water" in a second mash using the other half of the grain. This whole approach is quoted by Randy Mosher as "a waste of both grain and men" in his "Radical Brewing" book.

I have done a couple of Parti-gyle brews. They make for a long brew day and some beer that is just about as usual and some "special" strength beer that is for "special" occasions. The more super strong beers I actually drink, the less appealing they are and the less attractive the proposition seems. But everyone should find out this eternal truth for themselves, I feel.

If you do an 8.2kg grain bill in an A-I-O your efficiencies are going to be rubbish. 75%? Dream On.

 

[MrJay83]

The efficiency sweet spot for the Grainfather is 4.5kg grain bill. This is proven to be a fair evaluation from my 200 or so uses. I cannot imagine an A-I-O system of 30L capacity being much different. An 8.2 kg grain bill is possibly best approached by either of two methods:

1. Parti-gyle - where you do a full volume first mash and take out say 12L of wort and boil that separately with hops for your strong beer. The volume taken is replaced by water at 65C to do a second mash. This maybe around 30mins and could be "capped" by adding the Crystal and other non-mash malts at this stage, just as if it were a normal brew.

2. Doble-doble - you mash with half the grain bill, sparge it a bit and use the wort produced to be the "water" in a second mash using the other half of the grain. This whole approach is quoted by Randy Mosher as "a waste of both grain and men" in his "Radical Brewing" book.

I have done a couple of Parti-gyle brews. They make for a long brew day and some beer that is just about as usual and some "special" strength beer that is for "special" occasions. The more super strong beers I actually drink, the less appealing they are and the less attractive the proposition seems. But everyone should find out this eternal truth for themselves, I feel.

If you do an 8.2kg grain bill in an A-I-O your efficiencies are going to be rubbish. 75%? Dream On.

I went for number 2. 6am start this morning That's an interesting quote. I haven't heard anything negative about it so I gave it a shot.

 

[Agentgonzo]

Well I just put 8.2kg of pale malt in the grainfather calculator and aiming for a 23L batch (such would be 25L in the fermenter) it came out at 1.074 OG for 75% efficiency.

Obviously your grain bill is different. I wonder why brewers friend is so markedly different. Even if there were specially grains, I would expect the OG to be similar

 

[The Baron]

I am with Slid in this big grainbills hit efficiency and 8.2 is big even if split like you said not the most efficient way to brew

 

[Agentgonzo]

I am with Slid in this big grainbills hit efficiency and 8.2 is big even if split like you said not the most efficient way to brew

Yeah, good point. But that will just mean you get a lower efficiency. It doesn't explain why the recipe and brewers friend give you different values for the same efficiency

 

[MrJay83]

Well I just put 8.2kg of pale malt in the grainfather calculator and aiming for a 23L batch (such would be 25L in the fermenter) it came out at 1.074 OG for 75% efficiency.

Obviously your grain bill is different. I wonder why brewers friend is so markedly different. Even if there were specially grains, I would expect the OG to be similar

It was only 5.65kg of malt and the rest made up by wheat and oats. Where I get it you don't get to see the grainbill on the kits until it arrives. Like I said... I'm relatively new to AG. Started with AG kits and am starting to order my own grains.