Mash out step volume/temp question

Long time no see, everybody! Thanks for still being here all you long-timers. Haven't brewed since late last summer until today, so I'm a little rusty here.

Today's recipe was an ESB that I bought as a kit at Midwest Brewing Supplies. I punched the recipe into BrewSmith (awesome program btw) and used its numbers for volume and temperature of the mash in, mash out and sparge. BrewSmith told me to put in 12.2 qt of 175* water to mash in and reach 154*, and I hit that spot-on. (I also had BrewSmith adjust for energy absorbed by the mash tun, and it worked out great.) Then it told me to add 4.9 qt of 198* water to step it up to 168* for the mash out. If anything, I added water that was slightly over 200*, yet it still only stepped it up to 159* actual.

How could BrewSmith have been so accurate with the mash in and be so far off with the mash out? I only got 68% efficiency because I couldn't get it to 168* for the mash out, even after adding nearly a gallon of boiling water in addition (got up to 164*). Is there something I did wrong, or could have done differently?


Mash tun: Coleman Xtreme 36 qt cooler with stainless steel braid (I only ever batch sparge)

Grain bill for this ESB:
9lb domestic 2-row
8oz Caramel 40L
2oz Chocolate
2oz Roasted Barley

The mashout shouldn't effect your effciency.

The mash out is just to stop the conversion process. Most people that batch sparge add the first runs to the kettle immediately so they will mash out the brew anyways. Then the sparge water which is usually 170 will mash out the rest of the mash. If you got a bad efficiency it could be because of a bad crush. Not hitting the mash temps or just not using enough sparge water, or if you are fly sparging channeling.

A hot mash out does more than just stop enzyme activity. It also makes the sugars in the wort less viscous thus easier to wash off the grain. Think of it like heating up any other sugar, the hotter it gets the more fluid it becomes. As for the beersmith mash out temp. I found it to be of little use to me as well. One of the main problems with it I had is that it doesnt take into account any temp loss during the mash so say you mashed in at 154 but during the mash the temp fell to 152 that could account for a couple of degrees. I know that doesnt account for all of it and I have encountered the same issue as you have. What I usually do is drain most or all of my wort off first without mashing out, then procced to raise to mash out temp, also I keep some boiling water on hand in case (and usually when) I miss my temps.

Yeah I was just curious as to the BeerSmith calculation inaccuracy, especially given its dead-on accuracy with the mash in calc. Glad to hear I'm not the only one that's encountered this. Maybe I should mention it to BrewSmith tech support instead of here. Sounds like there's a feature request in there too.

Hmmm... I had the homebrew supply store crush my grains for me. This sounds like the seeds of a grain mill purchase down the road..... much easier to justify now that there's no more SWMBO.