Major Strike Temp Error in Beersmith?

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sudsmcgee

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I just brewed a big 5-gallon Wee Heavy yesterday in my Coleman Extreme 70 qt cooler. I used Beersmith to calculate the proper strike temp, and I measured the grain temp and cooler temp right before mashing in. I used the strike temp Beersmith called for, which was 172.3 degrees for a 155 degree full-body mash of 18.25 lbs of grain. I keep my cooler and grain inside the house to stay "warm" during the winter months, so the cooler and grain were both about 67 degrees. I measured my temps with a Thermapen, so I know they are accurate.

So, with all this being said, my actual mash temp ended up being 149. I went with it and mashed for 75 minutes, but I was hoping for a full-bodied beer.

As far as I know I have my specific heat measurement set correctly in Beersmith. My mash tun volume is 17.5 gals, my mash tun weight is 15 lbs (scale measurement) and my mash tun specific heat is 0.30.

I drained the HLT into the cooler using a short piece of silicon tubing with the cooler lid basically closed.

Does anyone have any idea why the hell my mash temp was so far off? I didn't preheat the cooler, but I didn't think I needed to with Beersmith.
 
The biggest thing you are missing for troubleshooting purposes is how much water did it tell you to use to infuse with?

** Additional Info **

I just ran a few numbers and recreated your setup based on your numbers - here is what I found.

Based on 172 strike temp to end at 155 you should have used ~28qt

Based on 172 strike temp to end at 149 you should have used ~20qt

So really 2 things could have happened here, either your grain/mash tun had actually gotten colder from when you measured, or the volume of water you ran into the tun was low. I've also noticed about a 2-3 degree temp drop when I move water from one vessel to another, even with a short hose... couple a few degrees temp loss with a cold mlt and a little less volume and everything adds up for the low mash temp you saw. Pre-heating your mlt could help you in this situation.
 
Thanks for your feedback. I mashed in with 5.86 +/- gals (23.44 qt) of water (1.25 qt/lb), so I would have expected at least 152'ish using your numbers. Oh, and I have my deadspace listed as 0.15 gals if that means anything.

I'm sure it has to do with being cold outside. In the summer I usually hit my mash temps right on. Even though I shouldn't need to, I guess I'll just preheat my mash tun in the winter months.
 
Playing around with the tun temp and grain temp only raises the strike water temp by +/- 1 degree or so. I'm still not seeing where the drastic heat loss occurred other than the water cooling off as you suggested. This must be a factor because nothing else makes sense.
 
Yeah, it sounds like it was pretty cold and probably windy as well... the large open surface area of the Coleman probably allowed the first few gallons of water to cool off much faster than calculated as they were run into the tun, even with the lid closed (and probably allowed a few extra degrees to come off when the lid was opened and the mash was stirred during the dough-in). I know you said you took your measurements of your tun and grain, but was that with them sitting inside? If so, how long did your grains and tun sit outside before you added water? Also, just out of curiosity, what was your ambient temp that day?
 
I measured the grain immediately before mashing in and adjusted the temp in beersmith to get a corrected strike temp. I also literally walked my cooler from inside the house and had the strike water inside of it within 2-3 minutes, so I don't think that's an issue since the lid was closed. There definitely was a crap ton of steam that came off the water though until I got some grain mixed in, and it did take me 5 or so minutes to mash in.

It was in the mid 20's here yesterday, but probably a little warmer in my garage (I'd guess 35 or so).
 
OK, so here is my last question (I hope). How do I figure out what the water temp should be inside the cooler after a few minute rest and right before i mash in? That would probably be the most helpful piece of information at this point to see if the water is cooling off too much before I can mash in.
 
I would heat my strike water about 5 degree hotter than calculated then measure what it is when you run it into the tun. That will tell you what the temp loss will be when it is cold out like this. If you are close to your normal calculated strike temp then go ahead and dough in and see where you steady out at. The good thing about being a little hot is that you can use the cold to your advantage and just stir a few minutes until you get your correct mash temp, then close your lid and you are good to go. I think you will be surprised about how much heat is lost while you are running the strike into the mash tun, especially in the cold.

Good luck
 
FWIW, my setup was a little screwy at first as well. I dialed it in by reducing the mash tun weight until the calculations matched real life.
 
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