Efficiency questions

[Bud Brewerson]

Hello Brew Community.

I'm a noob to brewing. I've jumped head first into all grain. Ive done a few batches and loving it!
I do have a question though.

I have been hitting my preboil gravity ok, never over but pretty close too, but the final runnings always seem to be high. How come? Why is that sugar not increasing my preboil why is there a lot left behind? 

thanx!

[Crusader-Rob]

Are you using Beer Smith?

what is the difference between Pre Boil and post boil Grvity based on your software and your actual.

I typically get 6-8 point over 60-90 min boils.

[Bud Brewerson]

yes I'm using BeerSmith. Eff is set to 70. 
my preboil, post boil gravity, total kettle volume and final volume in the fermenter is pretty much dead on. A few points lower than what BS suggests and a couple of liters lower or higher than the suggested volume in the fermenter.
But the final runnings coming out of the mash are 1030 on the last two brews.

Am i using too much grain? 

[Peter Smith]

are you stiring the mash at all?   

[Cain Harland]

I'm rethinking the whole string business, I usually give it a good stir at mash in to wet the grain then leave re circulation to do the rest. Last brew I kind of did in layers in an attempt to avoid a stuck sparge.  Pilsner malt on the bottom stirred the left to form a filter bed then flaked wheat on top also stirred but with minimal mixing of layers. This was a 1.5 hr step mash with RIMS. Re circulation did not take enzymes where needed and I got gravity of about what you would expect from just the pils, wort was not very sweet. So I stuck the egg beaters in which served to both break up the flaked wheat and mix everything very well. About 15 mins later I had sweet wort and ended up with probably the best efficiency I have ever had. No stuck sparge either.

It a bit of an extreme example and could have mostly been dealt with by mixing grains on their way in to the mash tun but it says to me is that although re circulation does a good job of evenly heating the tun its probably not doing a great job of moving enzymes around possibly due to channeling.

Makes me want to build a mash stirrer to sit in the tun and gently stir at just 1 or 2 revolutions a minute. But failing that I might just get a plaster mixer that goes on the drill and give it a good mix at low speed at say 15 and 30 mins.

[Rhys Williams]

I think you are over engineering and over complicating here.... If you ensure everything is wet and not clogging together at the beginning, You wont have the issue. As you add the grain into the water - stir at that point, and ensure everything gets wet and ensure the dry stuff does not bind together.

[Cain Harland]

Rhys,

Your almost certainly right there, but isn't that what we do as home brewers? We love to over engineer the shit out of everything, otherwise we would all be no sparge BIABing and sacrificing a bit of efficiency for a lot of time and simplicity. No disrespect there, I think those guys have it right in a lot of ways but over engineering a brewery is part of the fun for me.

Bud,

How are you sparging? Whats your mash tun? If your trying to fly/continuous sparge maybe try batch. Fly is technically capable of higher efficiency but a lot of things have to be perfect, batch eliminates a lot of the issues so often ends up higher.