MLT temp loss and temp location

Is there an acceptable range of temp loss for your MLT? I have a square cooler and I think I lost 5 to 10 degrees after 60 minutes. I say "think" because I saw some variation when moving the thermapen around. That's why I was also going to ask where is the best location for taking a temp reading? I can't get into the grain bed with my thermapen but I see a difference in the center vs the sides and near the surface vs a few inches below the surface.

I assume the ideal is zero loss and uniform temperature inside the MLT but is that what everyone gets in reality?

You've got to anticipate some of the heat loss into the cooler itself. You put the water in nice and hot, like 175F, and close the lid for 10 minutes. Open it up and stir until it reaches your normal dough-in temp, probably 164F. Now the cooler has all the heat it can hold and won't take anymore.

Bobby_M said:

You've got to anticipate some of the heat loss into the cooler itself. You put the water in nice and hot, like 175F, and close the lid for 10 minutes. Open it up and stir until it reaches your normal dough-in temp, probably 164F. Now the cooler has all the heat it can hold and won't take anymore.

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Hmmm, that's a plan I hadn't thought about. BeerSmith has me mashing in at 165 and if I mash in between 165 and 170 it hits the mark of 154 fairly well. So if I tried going in at 175 to 180 it might start a bit high but I could stir after 10 to 15 minutes and it would probably fade to the 155 range.

Maybe I'll try that next time. Certainly cheaper than going out and buying another MLT.

BeerSmith assumes no heat loss. To reduce the amount of heat loss your cooler experiences start by adding the water to the cooler at say 175, you will lose several degrees intitally as the cold cooler steals energy from the hot water, so stir and close the cooler for 10 minutes. Then when the water inside is 165F add your grains, this will ensure you get the right temperature and if your cooler is pre-heated you shouldn't lose more than a degree or 2 over an hour mash.
As far as location in the cooler goes, mix really well to eliminate dough balls to have an even mash mixture and it should be pretty close. That being said consistency is key so it's a good idea to always measure in the same spot, personally I measure in the middle of the cooler about 3 inches deep.

pretzelb said:

Hmmm, that's a plan I hadn't thought about. BeerSmith has me mashing in at 165 and if I mash in between 165 and 170 it hits the mark of 154 fairly well. So if I tried going in at 175 to 180 it might start a bit high but I could stir after 10 to 15 minutes and it would probably fade to the 155 range.

Maybe I'll try that next time. Certainly cheaper than going out and buying another MLT.

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No, the water goes in and you don't add the grain until the cooler takes heat. You don't want the mash to start out at 160F.

Bobby_M said:

No, the water goes in and you don't add the grain until the cooler takes heat. You don't want the mash to start out at 160F.

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Exactly. Add the hotter water. Stir it up and cover it, and walk away for 10 minutes. I bet you'll be surprised how much the temperature of the water drops! It's a LOT. Today, I used 178 degree water and within 15 minutes the water was at 167, my strike temp. THEN I added the grain.

You want to go at least 10-12 degrees higher, to account for the heat loss that will occur when the cool/cold MLT "sucks out" the heat of the water. Once you preheat, you'll lose less than a degree or two during the mash.

One point I'd like to make here- if you're getting different temperatures in different places, you're not stirring the mash enough! I add the grain to the water, and stir, stir, stir. Using an instant read thermometer, I check the temperature in several places. If they are different (more than a few tenths of a degree), I stir more. Once the temp is equalized throughout, and the cooler is preheated, you shouldn't have any problems.

About to do a bit of a threadjack, but your questions are already answered so oh well \m/

What's a good way to make up for a bad mash? Say you started off at 160 instead of the 155 you were aiming for, and it took a decent time to drop it? Should you still aim for 155, or adjust to a bit lower for the remainder?

Yooper_Brew said:

Exactly. Add the hotter water. Stir it up and cover it, and walk away for 10 minutes. I bet you'll be surprised how much the temperature of the water drops! It's a LOT. Today, I used 178 degree water and within 15 minutes the water was at 167, my strike temp. THEN I added the grain.

You want to go at least 10-12 degrees higher, to account for the heat loss that will occur when the cool/cold MLT "sucks out" the heat of the water. Once you preheat, you'll lose less than a degree or two during the mash.

One point I'd like to make here- if you're getting different temperatures in different places, you're not stirring the mash enough! I add the grain to the water, and stir, stir, stir. Using an instant read thermometer, I check the temperature in several places. If they are different (more than a few tenths of a degree), I stir more. Once the temp is equalized throughout, and the cooler is preheated, you shouldn't have any problems.

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I thought I read somewhere that you add the water to the grain and not the other way around. So that is what I have done from the start.

I did read about preheating the MLT so I normally take a tea kettle and let it boil and dump whatever is in there into my MLT. I do this about 15 minutes prior to when my strike water is ready. I then just dump this water out, add my grain, then add my strike water. If that sounds wrong let me know.

I can almost guarantee that I am stirring enough. It would be impossible for me to stir more and not rip out the SS braid. Plus if I took more time to stir I'd end up losing even more heat.

It sounds like what everyone is saying is (using my recipe from today) I should be adding my 13.75qt of 165 F water to my cooler and then waiting 10 minutes. Then dump my grains and stir. Then take a temp and then start the 60 minute timer. That would be a very new procedure for me.

With all this worry on the temp somehow I managed to get 79% efficiency into the boiler. I never scored that high before.

I pre-heat the mash tun with ~4 gallons of hot (I use ~180, not boiling -- it may warp) and leave it sit for 15 minutes. Dump that, pour in the water for the mash and then add the grain and stir. Works like a charm. Essentially, this gives me zero temp loss in the mash tun if I act fast enough and I only have to figure out the grain/water temp/mass to hit my strike temps.

pretzelb said:

I thought I read somewhere that you add the water to the grain and not the other way around. So that is what I have done from the start.

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I'm pretty sure it's advocated in "How to Brew" to add the water to grains. However most people I've talked to brew by adding overly hot water (175-180F) to their tun to pre-heat and then dump grains in once it cools to strike temperature. If you insist on adding water to grains you could pre-heat the tun and then dump the pre-heat water out, then add grains, then dump strike water back in.

The tea kettle is the right idea but not nearly enough volume to pre-heat a cooler, if you preheat with a larger volume you shouldn't lose more than 1 degree.

This procedure For today's recipe would look like this:
Heat 13.75 quarts of water up to 175F and add to cooler, stir, close lid, let sit 10 minutes
When the water's temperature drops to 165F THEN add your grains and stir like crazy
Once you get a consistent mash and temperature throughout close lid and mash.

iijakii said:

About to do a bit of a threadjack, but your questions are already answered so oh well \m/

What's a good way to make up for a bad mash? Say you started off at 160 instead of the 155 you were aiming for, and it took a decent time to drop it? Should you still aim for 155, or adjust to a bit lower for the remainder?

Click to expand...

Just stir! You can drop from 160 to 155 with just a few minutes of stiring. Once you get it down proceed as planned

Veinman said:

I'm pretty sure it's advocated in "How to Brew" to add the water to grains. However most people I've talked to brew by adding overly hot water (175-180F) to their tun to pre-heat and then dump grains in once it cools to strike temperature. If you insist on adding water to grains you could pre-heat the tun and then dump the pre-heat water out, then add grains, then dump strike water back in.

Click to expand...

That is probably where I read it. But if everyone else is doing the opposite then I can try it.

This procedure For today's recipe would look like this:
Heat 13.75 quarts of water up to 175F and add to cooler, stir, close lid, let sit 10 minutes
When the water's temperature drops to 165F THEN add your grains and stir like crazy
Once you get a consistent mash and temperature throughout close lid and mash.

Click to expand...

I can try that next time. I don't like the idea of adding a large amount of water that will just be dumped prior to adding strike water. I'm already wasting plenty of water for my chill and it would take a long time to heat both batches of water.

After 20+ batches I'm still learning. I'm not sure if that makes me happy or sad.

Adding water to the grain is "doughing" in. In a traditional step mash you would add small amounts of luke warm water to the grain and stir it to make a thick paste. Then add hot water to bring it to the first rest (probably a protein rest). Then do a decoction to reach the scarification rest.

But with most modern malts a simple one step infusion mash is really all you need. And since we need to heat the cooler, most people add the water then the grain. Logistically it make more sense.

Everyone above is much more knowledgeable than I, but I had good results with 185F water in the cooler for 15 minutes before hand to heat the cooler, then used the exact temperature recommended by Brewtarget for the mash and hit my strike temperature right on.

You might want to feel around your cooler and you can find if there's a big source of heat loss to the outside. Mine stays cool all around the perimeter during the hour mash, but the lid gets very hot. My lid is not insulated. I put a coat on top and it reduced the heat loss significantly.

Most people who see 5-10F drops in mash temperature are losing most of that heat into the cooler itself for sure.

Another thing to keep in mind when you put your strike water in hot, like 175F, is to tilt your cooler to each sidewall a bit so the upper areas get a chance to suck some heat.

The reason some people suggest to add water to grain is so that it's not overheated. One way to combat that is to not add a small amount of the grain at a time. I like to add half the grain, stir quickly, add the last half, stir quickly. There is no way you're going to denature the enzymes during a 3 minute ride at 160F. The inner cores of the starch clusters are barely even moist in that period of time.

Bobby_M said:

There is no way you're going to denature the enzymes during a 3 minute ride at 160F. The inner cores of the starch clusters are barely even moist in that period of time.

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+1 I usually end up very hot and have to stir quite a bit to get it down to my target temp. I've never had a problem where the enzymes were denatured. I always get excellent conversion, very high mash efficiency and highly fermentable worts.

Bobby_M said:

Most people who see 5-10F drops in mash temperature are losing most of that heat into the cooler itself for sure.

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+1 -- It's not the stirring that's making the temperature drop, it's the mash equalizing with the cooler. Once it equalizes, stirring isn't going to do much of anything unless you're outside in the middle of a blizzard.

Bobby_M said:

Most people who see 5-10F drops in mash temperature are losing most of that heat into the cooler itself for sure.

Another thing to keep in mind when you put your strike water in hot, like 175F, is to tilt your cooler to each sidewall a bit so the upper areas get a chance to suck some heat.

The reason some people suggest to add water to grain is so that it's not overheated. One way to combat that is to not add a small amount of the grain at a time. I like to add half the grain, stir quickly, add the last half, stir quickly. There is no way you're going to denature the enzymes during a 3 minute ride at 160F. The inner cores of the starch clusters are barely even moist in that period of time.

Click to expand...

Next batch I am going to try adding the water at 175 and waiting for it to hit 165 before adding my grains. Should be interesting. If I still see a big drop after 60 min I have another square cooler that I might be able to use with my SS braid.

Thanks everyone.