Author Topic: BIAB - Missed Mash Temp  (Read 2209 times)

Offline mckeontj

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BIAB - Missed Mash Temp
« on: May 19, 2019, 07:25:54 AM »
Looking for some guidance. I'm currently attempting my first brew-in-a-bag batch (technically, a mash-in-a-bag) and I've hit an early snag.

Aiming for a mash of 154, BeerSmith told me to heat the "strike" water in the tun to 159. This seemed low to me, but I followed the instructions. After adding the grain, I hit a decidedly unimpressive mash temp of 130. What happened? How/Why was BeerSmith off? What do I do next time?

Some details -

Mash Tun - 10 gallon cooler
Grain - 10 lbs total
Grain Temp - 72 degrees (this was correctly inputted in BeerSmith)
"Strike Water" Temp - 160
Mash Temp (goal) - 154
Mash Temp (actual) - 130

Is it worth continuing with this beer?

~Desperately Seeking Mash Temp

Offline Oginme

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Re: BIAB - Missed Mash Temp
« Reply #1 on: May 19, 2019, 08:13:32 AM »
Things to look at:

You are doing mash in a cooler, did you have the weight of the cooler set in your equipment profile?  What about the temperature of the cooler?  And did you have checked for the software to adjust the strike temperature to account for the temperature of your equipment (cooler)?

My guess without seeing your recipe (you can always export that as a .bsmx file by highlighting the recipe and clicking on 'file' > 'export selected') is that the last question is the reason you came in too low in temperature.

Post your recipe below if it is not the case and we can view it to see just what is going on.

Recycle your grains, feed them to a goat!

Offline BOB357

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Re: BIAB - Missed Mash Temp
« Reply #2 on: May 19, 2019, 08:34:28 AM »
I do full volume MIAB in a 10 gallon Rubbermaid cooler and Beersmith always gets me to within a degree or two of my mash temperature. I just looked at a recent brew and I mashed 10.5 lbs. of grain with a target mash temperature of 152 degrees. Both my mash tun and grain temperatures were 69 degrees +/-  one degree. Adding 7.66 gallons of strike water at 161 degrees put me at 153 after doughing in.

In order to hit your numbers you must have an equipment profile that represents your actual equipment, including volume losses. Your measurements and all inputs must all be accurate. There is something drastically wrong with one or more of your entries. There's no way you lost 30 degrees doughing in if your inputs were anywhere in the ball park.


If you post the recipe here, I'm sure your error(s) will be found and pointed out to you. Without the benefit of knowing what you did wrong there's really no way do advise you on how to try and salvage the brew.
Bob

Offline mckeontj

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Re: BIAB - Missed Mash Temp
« Reply #3 on: May 19, 2019, 08:57:55 AM »
Thanks for the quick reply.

I've checked my equipment profile and can't see where the mistakes may be. The "adjust temperature" was not clicked, but, when I did click it, strike temp went from 159 to 163 - not sure this would have made a material difference.

Here's the recipe, as well as some screenshots of the mash and equipment profile. Any thoughts? I know there's something I'm missing.








Offline Kevin58

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Re: BIAB - Missed Mash Temp
« Reply #4 on: May 19, 2019, 08:58:56 AM »
@oginme hit on some key measurements you need to be aware of with the temp and weight of your mash tun... and @BOB357 hit another; the temperature of your grain. Another question is... are you mashing at full volume?

When I did BIAB my strike water temp was regularly calculated at only 4 to 5 degrees above my mash temp. I was skeptical too the first time I did it but it worked. However I had created both custom equipment profile and mash profiles. With those profiles dialed in the software will be your best friend. Without accurate profiles you sometimes might as well just be guessing.

Equipment Profile tutorial: https://youtu.be/QmW7pwQP5mQ

Mash Profile tutorial: https://youtu.be/VKiEjhxo2oo
« Last Edit: May 19, 2019, 09:02:02 AM by Kevin58 »
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Offline mckeontj

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Re: BIAB - Missed Mash Temp
« Reply #5 on: May 19, 2019, 09:12:11 AM »
The tun weight is in the equipment profile. The tun temp is also there, but I'm heating the strike water in the mash tun and so I'm not how this would make a difference. And yes, I'm mashing at full volume.

Thanks for the videos. I followed them when I set initially up my profiles.

Offline Oginme

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Re: BIAB - Missed Mash Temp
« Reply #6 on: May 19, 2019, 09:21:57 AM »
Thanks for the quick reply.

I've checked my equipment profile and can't see where the mistakes may be. The "adjust temperature" was not clicked, but, when I did click it, strike temp went from 159 to 163 - not sure this would have made a material difference.


Actually, having the box unchecked is 95%+ of your issue.  While it does not seem like it, the thermal capacity of the water at 31.93 quarts makes a huge impact on the strike temperature with only a few degrees difference.  Reread BOB357's post about his strike temperature and target.

If you were heating the water in the mash tun (for which you have the specific heat listed for plastic), then the temperature of the mash tun should be set to reflect the value.  Having the 'adjust temp for equip' box unchecked would result in too high of a temperature as the program does not account for any temperature or thermal value of the equipment.  If it your mash tun (cooler) was at strike temperature, you would have ended up with too high a mash temperature.

Recycle your grains, feed them to a goat!

Offline Oginme

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Re: BIAB - Missed Mash Temp
« Reply #7 on: May 19, 2019, 11:18:36 AM »
Just as a gut check to thermal capacity of the water:  water has a heat capacity of 1 cal/gm-degC.  31.93 quarts of water at 8.34 lbs/gal is 66.6 lbs of water or 30,200 grams.  Your mash tun is 10.8 lbs (4,900gms) at 0.3 cal/gm-degC and the grain is 10 lbs (4,500 gms) at 0.38 cal/gm-degC. 

So your ambient equipment going from 72F (22C) to 154F (68C) would require:  4,900 * 0.3 * (68-22) + 4,500 * 0.38 * (68-22) = 67,600 + 78,700 = 146,300 cal

If the water was at 164F (72C) strike temperature it would contain: 30,200 * 1 * (73-68) = 151,000 cal.

Given a little heat loss and rounding error this is pretty close. 

This again supports the observation that not having set your mash to account for the thermal rise of the equipment was your issue. 


Recycle your grains, feed them to a goat!

Offline BOB357

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Re: BIAB - Missed Mash Temp
« Reply #8 on: May 19, 2019, 12:13:33 PM »
The tun weight is in the equipment profile. The tun temp is also there, but I'm heating the strike water in the mash tun and so I'm not how this would make a difference. And yes, I'm mashing at full volume.

Thanks for the videos. I followed them when I set initially up my profiles.


Heating the strike water in your cooler/mash tun does not mean that you are dumping hot water into the cooler, but are actually applying heat in the cooler in order to bring the water up to strike temperature.

If you are actually heating the strike water in the cooler, the "adjust temperature" doesn't apply. This would mean that you have a serious problem with either your volume and/or temperature readings.


« Last Edit: May 19, 2019, 12:26:31 PM by BOB357 »
Bob

Offline mckeontj

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Re: BIAB - Missed Mash Temp
« Reply #9 on: May 19, 2019, 02:40:12 PM »
Heating the strike water in your cooler/mash tun does not mean that you are dumping hot water into the cooler, but are actually applying heat in the cooler in order to bring the water up to strike temperature.

If you are actually heating the strike water in the cooler, the "adjust temperature" doesn't apply. This would mean that you have a serious problem with either your volume and/or temperature readings.

This is my concern. I heated the strike water in the cooler mash tun. 8 gallon full volume. Thermometer read 160 and then 130 after mashing in.

Offline Oginme

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Re: BIAB - Missed Mash Temp
« Reply #10 on: May 19, 2019, 02:51:36 PM »
From this information, I would suspect that either of the readings is way off.  If you heated the water in the cooler (how?), then you may have inconsistent temperature readings if the water is not being recirculated or stirred.  If we assume that the initial strike temperature is correct, then the same goes for your mash temperature.  Is your thermometer fixed in location, or are you taking readings around the mash tun?
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Offline mckeontj

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Re: BIAB - Missed Mash Temp
« Reply #11 on: May 19, 2019, 04:41:35 PM »
From this information, I would suspect that either of the readings is way off.  If you heated the water in the cooler (how?), then you may have inconsistent temperature readings if the water is not being recirculated or stirred.  If we assume that the initial strike temperature is correct, then the same goes for your mash temperature.  Is your thermometer fixed in location, or are you taking readings around the mash tun?

I used a bucket heater to heat the water. I'm wondering if you're onto something about the temperature reading location. I used a fixed location and, looking back, should have circulated the water to make sure the heat was being distributed. In the small space of a cooler, could that make that big of a difference? Would be great if it was that easy.

Offline Oginme

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Re: BIAB - Missed Mash Temp
« Reply #12 on: May 19, 2019, 05:05:58 PM »
I used a bucket heater to heat the water. I'm wondering if you're onto something about the temperature reading location. I used a fixed location and, looking back, should have circulated the water to make sure the heat was being distributed. In the small space of a cooler, could that make that big of a difference? Would be great if it was that easy.

Short answer is yes, it makes a big difference.  In my kettle, I can find an easy 2 degree variation depending upon location once I have doughed in.  I always advocate for stirring the mash for at least 5 minutes to equalize the temperature as much as for making sure all the grain is thoroughly wetted through.
Recycle your grains, feed them to a goat!

Offline dtapke

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Re: BIAB - Missed Mash Temp
« Reply #13 on: May 20, 2019, 08:22:33 AM »
Definitely sounds like a stirring and temperature checking error in potentially multiple different aspects.

First, when heating with a "bucket heater" the heat from the heater will create a thermal rise of water. if you're checking the temperature above the heating element it will read high if you're not stirring.

I've actually screwed this up on my HLT before, heating my sparge water up hotter than it needs to be because of where i read the temperature doesn't read accurately during that stage. I now read it in a different spot during that step and recirculate the water during my heating.

Second, when mixing your grain and water, you need to make sure you mix REALLY WELL. it's very easy to get hot spots and cold spots. I use a big mixing thing for mixing drywall in 5g buckets. Works great. "mash paddles" generally suck IMO.
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