HELP!!...mash temps

How the fark am I loosing 30 degrees to the tun?? According to promash, for my 8.5 lbs of grain my strike water should be around 168, which it was. After dough-in my grain bed was at about 135. I've added 2 quarts of boiling water and I'm at 138. Do I keep adding water?? This is a Scottish BTW

What the hell are you using for a mash tun? Liquid Nitrogen?

It's a hand-me-down 20 gallon plastic tun, which sits in an insulated plywood box. Maybe the dense foam insulation is pulling the heat out?? Anyway, should I keep adding water to try and rescue this, or consider it a lost cause?

Was the grain, and mash tun, in thr fridge/freezer and not have time to warm up? What's the temps where you are? What are you using for a mash tun (as already asked)?

I think you need to figure out why you got such a large temp drop. You could pull some of the wort/mash and heat it to get your temp. I would verify the thermometer readings first though. What are you using for a thermometer?

I would try and get it till about 148 if you can. Mash for at least an hour or maybe more. The lower the mash temp the longer you have to mash for.

Did you pre heat the mash tun?

Is the thermometer accurate?

I calibrated my digital thermometer before brewing. Grain and tun were at ambient temps...about 67 - 68. I'm stumped. Will I get any kind of conversion at all with mash temps this low???...I'm approaching 6 gallons of water in the mash right now. FUBAR

Do a Decoction ... Here is a calculation:
to determine the amount to extract:
((D-T) * (G * (0.3125+R) / (212-T))
Where
D = Desired Temperature of mash after decoction is added back in
T = Current temperature of mash
G = Total Grain in LB
R = Ratio of Quarts of water per pound of grain
212 is the Temp in F of the decoction.
0.3125 is the consistent approximate of the mashes capacity to absorb heat.
This will tell how much to extract from the Mash Tun.
You bring the extract to 150 to 153 F and rest 10 minutes. Then bring the extract to a boil and boil for 10 minutes. Then add it back to the total mash to bring you to the next rest.

After you save this batch...... next time...... pre heat the mash tun....

BrewerinBR said:

Do a Decoction

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That is the answer!

Do not freak out - you are not even close to screwed. My first choice would be to slowly infuse boiling water until you hit temp (or run out of room), taking a reading while you stir. Do not just blindly dump in 2 gallons of boiling water while hoping things work out. If you do run out of room in the tun, then turn to decoction.

You actually did yourself a service by undershooting. Had you overshot by 30 degrees, this would be a different conversation. You are simply doing an unplanned step mash.....and that is like 400 level AG brewing.

Congrats!
Joe

iaefebs said:

After you save this batch...... next time...... pre heat the mash tun....

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For sure. Only my second all-grain batch and I'm going to MacGyver a Decoction. Here goes nothing. Thanks everyone.

So...how'd it go?

3 hour mash...hit 1.032 as my BG. Doing a 120 minute boil right now. My target OG is 1.038 to 1.041, so I might be good. I'm naming it "MacGyver's Scottish 70". Could be brilliant, could be garbage. I'll update you all in about 8 or 10 weeks.

It's going to be great!

Good Luck and let us know.!

Gropo said:

It's a hand-me-down 20 gallon plastic tun, which sits in an insulated plywood box. Maybe the dense foam insulation is pulling the heat out?? Anyway, should I keep adding water to try and rescue this, or consider it a lost cause?

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A 20 gallon tun for 8.5 pounds of grain is likely your problem. For such a small quantity you might be better served mashing in a smaller pot or bucket.

wilserbrewer said:

A 20 gallon tun for 8.5 pounds of grain is likely your problem. For such a small quantity you might be better served mashing in a smaller pot or bucket.

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Good point....there's a good 24" of dead-air space above the grist when I mash. The brewer that I inherited this from (before he went commercial) routinely made 20 gallon batches; I'm a 5 gallon batch brewer. All-in-all, the whole decoction process was simple, and this style might really benefit from it. I REALLY appreciate everyone on this forum helping me out in my moment of panic. Cheers.

Naw, I held 6# of grain in a 54qt MLT cooler. Preheat your mash-tun next time. Also when adding boiling water, make sure you stir it up and wait about 5 or 10 minutes. Trust me on this one, it takes a LONG time to get heat dissipated.

Last weekend I actually made an enormous mistake and added 2g of boiling wort to the MLT and the temp was 15 degrees less so I added a pot of boiling water and it shot up to 40 degrees above where I wanted it to be so I dropped in 4 ice packs which I happened to have around. When adding boiling liquid always let it sit, always, before taking the temperature.