Extract and efficiency

[Buster Bunting]

Hello,

OK so I've got a bit of an issue.
When I brew, I write recipes on beersmith and set my efficiency at 68%. I figure lower is better at this stage.
I'm still having issues reaching my target pre boil and thus post boil OG.

I'm more often then not 10points lower then expected. 
Im brewing between two different system and still the same thing is happening.

My mash pH is always 5.3, mashing at 66C, collecting the exact amount pre-boil, I calculate run off so it takes an hour to fill my kettle the final runinnings are between 1020-1010 (pH~5.6)

What on earth is going on? 
Please help me!

[Sam DT]

What's your final volume - are you hitting your target in terms of L into the fermentor? Too much sparge water will dilute you down. Also leaving too much in the pot post boil could be a killer. I generally use a couple of liters less than I think I'll need and top up in the fermentor if required.

Gravity will also have a big impact, I range around 70% for standard OG Brews (around 1.050) but will go right down to 60% or less for a double IPA.

[Buster Bunting]

Hmmm good point. 
Im not too sure how much trust IU have in BS when calculating the water volume input vs out.
The last batch was meant to be 18L into Kettle, pre boil 1.056 with 13L in to fermentor at 1.065
I ran numbers closer to 1.048 in to KT @ 18L. I had 2.5l left in mash tun at 1.020.

1.055 post 60min boil and 12L into fermentor. 
I'm starting to think it two issues.

1)Something (not) happening in the mash
2) boil off volume?

[Sam DT]

So looks like you've slightly underestimated your boil off - do you tip the entire pot into your fermentor or do you rack off and leave the trub behind? - I find I can usually get a couple of extra L if I let it settle before racking off. The other approach is just to dump the lot into the fermentor and let it settle out in there - I generally err on the side of more trub in the fermentor vs leaving wort in the pot.

Anyway - that is minor - from the above your issue looks to be up-stream i.e. you're already down when hitting your target pre-boil volume. As you nailed your pre-boil volume I'd say the water volumes are all good and you need to look at your mash and sparge efficiency.

As the others have said crush can make a big difference (I get upto a 10% swing between single and double crush in BIAB (no sparge issues so can crush fine)).

What temperature are you sparging with? I think you'd ideally be doing it at mash-out temps I.e. around 75-78C to get maximum extraction.

Flow in your tun may also be an issue. I'm no expert as I BIAB but if you sparge and all your water runs down the side and misses your grain it'll really screw with your extraction. The easy way to test this is to do a BIAB batch and see if it lifts your efficiency (basically takes sparging out of the equation). To be honest for half batches I'd probably just run BIAB anyway - will simplify your process - just be aware that as you're doing a full volume mash you may need to up your acid additions to keep the pH in check.

Good luck!

[Druid]

Your issue with boil off volumes may be this -

There used to be an issue with Beersmith with the heating/cooling shrinkage parameter in the equipment settings.  If you didn't set it to zero, it consistently generated predicted pre and post boil volumes and gravities that didn't match up ie. (pre boil gravity x pre bool vol) didn't equal (post boil gravity x post boil vol)

I set it to zero after noticing that I was consistently getting a  lower post boil gravity than what I was expecting.

Here's a link to the post I made about it

[Buster Bunting]

The shrinkage value is set to 4%.
I haven't changed that. Are you suggesting to set that at 0%?

What does everyone else have this set to?

[Druid]

If BeerSmith still has this issue then yes - set it to zero.

Before you change it though, you can check for yourself to see if it does still have the issue by looking for the predicted variables I mentioned above in your beersmith recipe (pre boil vol, pre boil gravity, post boil vol, post boil gravity).

Basically, if the beersmith calcs are correct, the following formula must hold true:

pre boil vol x pre boil gravity = post boil vol x post boil gravity

Remember to subtract 1 from the gravities before using ie. 1.036 => 0.036

My observation was that it wasn't holding true - until you set the shrink factor to zero.

Pretty sure the other post I referenced goes into more detail.

If you make the change, your volumes will be down a little but at least your predicted gravities will be correct

[Session M]

I calibrate my system using water. Add water yo typical boil volume and boil for 1 hour. Note post boil volume. This is your hourly boil off rate. Allow water to cool in kettle and check volume. Enter the difference as shrinkage.one worked out to be 6%! Transfer to fermenter as you would at brew day leaving behind about as much behind as you would for standard trub. From here you get your trub loss. Once all that's dialed in you should get within 2 points and quantity should be spot on. Do a brew and adjust brew house efficiency
From there. Will probably only be out by 2% or so. I can now hit the figures exactly using thus calibration. You would then know if efficiency is lost in the mash.