Mash Temperature Woes

[lmckenny]

Tried my hand at BIAB today and am ready to pull my hair out. I was targeting a mash temp of 156. I added the grain into the bag at 157. Temperature inside the bad looked to drop 10-20 degrees. Starting heating up the put. None of my three thermometers (including a thermopen) were measuring over 150 inside the bag when I started seeing bubbles appear! I measured outside the bad and I was on the cusp of boiling!

Can you not have the thermometer touching the grain?? I've looked at various articles and am at a loss.

 

[chickypad]

It's normal to drop about 10-15 degrees doughing in, you probably want to use a mash calculator to check your strike temp. How big is your bag, and are you stirring everything well? Here is a pic of one of my mashes. There shouldn't really be much "outside the bag" room. It's pretty impossible not to have the thermometer touching the grain.

 

[Subdivisions]

If your mash temp was 156 then you shouldn't have been dumping grain in when the water was 157. Like chickypad said, use a mash calculator to figure out what temperature to get your strike water to. It will vary depending on the amount of grain you're putting into the pot.

Here are a few to check out. I prefer priceless' since I do a sparge

http://biabcalculator.com/

http://simplebiabcalculator.com/

http://pricelessbrewing.github.io/BiabCalc/

 

[lmckenny]

What has me puzzled is why my (3!) thermometers were not accurate inside the bag. I pull the bag off of the side of the pot and got vastly different (higher) temperature reading.

I added the grain at about 2 cups at a time so I could stir them in and not clump. I had 6 lbs of grain in 4 gallons of water for a 2.5-3 gallon batch.

 

[chickypad]

My point is the entire contents of the pot should be "in the bag". The grains and water should be completely mixed, you talk about pulling the bag off to the side as if that's not the case. If you've got that huge a temp stratification (less than 150 to near boiling) then you are not stirring well.

 

[brew703]

What has me puzzled is why my (3!) thermometers were not accurate inside the bag. I pull the bag off of the side of the pot and got vastly different (higher) temperature reading.

I added the grain at about 2 cups at a time so I could stir them in and not clump. I had 6 lbs of grain in 4 gallons of water for a 2.5-3 gallon batch.

I only do BIAB and never had a problem. The strike temps depend on alot of variables. I've used Priceless, Brewers Friend and Beersmith and none of the strike temps were exact. But they are only as good as the info you enter. Priceless is probably the best and I tend to use it most. Last weekend I overshot my mash temp by 2 degrees and it was just right after adding my grains.
The issue I have is I use a cheap kettle and it's not very thick. I have a new kettle that is thicker so i am hoping that helps.
As for as temp measuring inside/outside the bag, I've had no issues and I use a Thermapen.

 

[Yooper]

The grain has be be very loose in the bag- the grain and water needs to mix as if there is no bag there at all. The bag is only there so you can remove the grain at the end, not to contain the grain during the mash. If the grain was actually packed in, and not loose, that would explain the difference in temperatures I guess. The entire grain/water mix should be a loose mash- all thoroughly incorporated so you wouldn't be able to tell where grain was and liquid was- think of it like a thin oatmeal, all incorporated.

 

[pablosbrewing]

Also - when you add heat in BIAB you stir, stir, stir.

 

[lmckenny]

Is it fair to say that it takes a lot longer to heat the kettle after the grain is added? My thought was since there's 7 pounds of grain in the kettle it would take a lot more BTUs to bring the water up to temperature (if I miss the Mash temp) that if there was no grain in the kettle.

 

[Chris_Primavera]

It's normal to drop about 10-15 degrees doughing in, you probably want to use a mash calculator to check your strike temp. How big is your bag, and are you stirring everything well? Here is a pic of one of my mashes. There shouldn't really be much "outside the bag" room. It's pretty impossible not to have the thermometer touching the grain.

I brew 5 gallon BIAB and typically use 14# of grain and never get a 10°-20° drop. 7°F is probably the most I have seen and mash calculators tell me I should be about 2°F above my strike temperature at mash-in. (and I usually wind up about 2°F low)

I think Yooper has it right - the only way to have grain at mash temperature and the water near boiling is to have the grain tightly packed, The mash should be a thin soup and the bag should line the kettle much the way a garbage bag lines a trash bin.

 

[pablosbrewing]

Is it fair to say that it takes a lot longer to heat the kettle after the grain is added? My thought was since there's 7 pounds of grain in the kettle it would take a lot more BTUs to bring the water up to temperature (if I miss the Mash temp) that if there was no grain in the kettle.

Using some approximations we can check:

• Specific heat of water is ~2 per quart
• Specific heat of grain is ~0.4 per pound
• Using the above at 2qt/lb mash it takes only ~10% more BTU's compared to heating just the water

Mash tends to insulate itself, so you do have to stir (more than you think) when adding heat in BIAB to avoid hot and cold spots, if you lift the bag while heating then stir when you drop the bag in again.

I use this whisk in my setup, makes mash in easy as well:
http://amzn.to/1LDXk2j

 

[lmckenny]

Using some approximations we can check:

• Specific heat of water is ~2 per quart
• Specific heat of grain is ~0.4 per pound
• Using the above at 2qt/lb mash it takes only ~10% more BTU's compared to heating just the water

Mash tends to insulate itself, so you do have to stir (more than you think) when adding heat in BIAB to avoid hot and cold spots, if you lift the bag while heating then stir when you drop the bag in again.

I use this whisk in my setup, makes mash in easy as well:
http://amzn.to/1LDXk2j

Thanks I just bought that wisk. I just realized that my oven is large enough to fit my pot and has proofing/dehydrating settings that can bring the temp down to 150. Think I will try it next batch!

 

[lmckenny]

I brew 5 gallon BIAB and typically use 14# of grain and never get a 10°-20° drop. 7°F is probably the most I have seen and mash calculators tell me I should be about 2°F above my strike temperature at mash-in. (and I usually wind up about 2°F low)

I think Yooper has it right - the only way to have grain at mash temperature and the water near boiling is to have the grain tightly packed, The mash should be a thin soup and the bag should line the kettle much the way a garbage bag lines a trash bin.

I was doing a recipe in Beersmith that called for 6-7lbs of grain in 4 gallons of water. Is that too thick?

 

[Chris_Primavera]

I was doing a recipe in Beersmith that called for 6-7lbs of grain in 4 gallons of water. Is that too thick?

Assuming we are still talking about BIAB, no that would not be too much grain for that volume of water.

The OP did not have too much grain, rather, it is likely the grain was too tightly packed.