Methods for Adjusting Temp in Mash Tun?

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

BigTexun

Well-Known Member
Joined
Feb 15, 2010
Messages
124
Reaction score
3
Location
Atlanta
I'm about to launch into the world of AG. Just wondering if the following ideas will work:

Let's say, I drop my grain into the mash water and the resulting temperature is too low.

What if, I pulled out say, 1/2 a gallon of water from the tun, heated it up to almost boil, and slowly add it back to the tun. Would that work?

Another thought if that won't work... I remove "1/2 a gallon" of mash tun water... and add it to the sparge pot... and quickly replace the 1/2 gallon I stole with fresh "boiling water" I had in another pot, ready for such a situation?

For cooling, what about just adding a few cubes of ice?
 
First thought would be a decoction of sorts. Second thought would through out high gravity wort so that would be a bad way to go. Ice cubes are fine. Online calculators are remarkably accurate if your thermometer is accurate so you shouldn't have to worry about not hitting the right temp. Maybe go a few degrees above the first time and keep the cooler lid open and stir until your temp falls to where you want.
 
Yup.

Yup.

Yup.

Unless your mash tun is super full, there's no need to remove the 1/2 gallon before adding the 1/2 gallon of boiling water....a bit of extra water won't hurt.

To really be accurate, use a mash temp calculator to determine how much water to add to raise x lbs of grain and y gallons of water by however many degrees you need.

Also, cold water might be better than ice so it equilibrates faster, (don't have to wait for ice to melt), but either should work.
 
I am assuming you are using a cooler as a mash tun or you wouldn't be asking this question. The easiest way to raise your temperature is to add more hot water. So so in small increments and you won't have too thin of a mash. To cool the mash open the lid or add cold sterile water. Ice cubes tend to freeze a lot of bacteria in them.
 
The best solution is to use a brew app like beersmith or something that you can use to calculate your strike temp. I have found it VERY accurate. The trick is to pour the water into your cooler roughly 5-7F hotter than your mash in temp. close it up, then wait 10 minutes. You are preheating the cooler so you don't drop low on your temp. Keep your grains in a location where the temperature is known and constant. I know my basement is always roughly 64-67F, so that makes the grain temp known. Then all you need to do is open up the cooler and stir the water until it reaches your target temp, add the grain, and you should hit within a degree or two.

If you are hot, no problem, stir until you reach the correct temp.

If you are low like 1-2F I personally would leave it. Its not gonna be a huge problem.

If you are low like 10F, then you screwed up and yeah... may want to move a large amount of the mash to your brewpot, get some heat on it, bring it up a little higher than what your target is, then move it back into the mash tun. I personally have never been below like 3F when using beersmith... and it was probably because I entered an incorrect grain temp.

Depending on your mash tun size, it may be impossible to boil 1-2 gallons of water and get it to fit in there. Moving that temp up with boiling water is difficult anyways. You're most likely trying to heat up 15-25lbs of grain plus another 6-8 gallons of water. One gallon of boiling water is only going to bump you up like 5F, minus the heat loss you will get from screwing around with the masher open.
 
I regularly pull a small decoction if my mash temp drops too low during the mash. I check twice over the hour, every 20 min. With my system, one quart of the mash boiled and added back usually bumps the total mash temp up 1 degree Fahrenheit, give or take.
 
I am assuming you are using a cooler as a mash tun or you wouldn't be asking this question. The easiest way to raise your temperature is to add more hot water. So so in small increments and you won't have too thin of a mash. To cool the mash open the lid or add cold sterile water. Ice cubes tend to freeze a lot of bacteria in them.

How important is it that the water be sterile? I mean, tap water is good enough, no?

PS: Just wonderin' since it'll all be boiled soon enough, won't that vaporize any chlorine and kill any bugs?
 
even though I use Beersmith and pre-heat my igloo cube, I always have trouble hitting temps. I make sure to have a half gallon of boiling water and a half gallon at 35 F in my keezer. After a few AG brews you'll know how much of each will get you the 1-5 degrees you're off by.

good luck!
 
How important is it that the water be sterile? I mean, tap water is good enough, no?

PS: Just wonderin' since it'll all be boiled soon enough, won't that vaporize any chlorine and kill any bugs?

Absolutely zero importance. Like you said, it'll be boiled. I don't sanitize, (or sterilize) anything pre-boil....there's just no need.
 
even though I use Beersmith and pre-heat my igloo cube, I always have trouble hitting temps. I make sure to have a half gallon of boiling water and a half gallon at 35 F in my keezer. After a few AG brews you'll know how much of each will get you the 1-5 degrees you're off by.

good luck!

Don't trust beersmith to know how many degree's your cooler will consume. That will vary depending on the ambient temp. Disable that, put in water slightly hotter than you need, and stir it down to the correct mash in temp.

You actually need the minerals that are in regular tap water. There's absolutely no benefit to using distilled water or something crazy. I add a half of a campden tab to my water to knock out chlorine and chloramines...
 
I have done two AGs so far and have had to decoct all mash long. My guess would be 6 decoctions per mash. It seems every time I check the temp is around 147, so I drain 1/2 gallon boil it then mix in.

My suggestion would be to preheat everything well.
  • Grains is a warm room leading up to the mash.
  • Boiling water steeped in the MLT just before mashing in.

One technique i read about and will try next is to: Add water heated over strike temp by just a litllle to your MLT, leave lid open to let it cool to your strike temp then add the grains. That way you know the water and MLT are at the strike temp. Then if you seal it and insulate your MLT, blanket whatever hopefully you won't have to spend to do much bringing up to temp.
 
Don't trust beersmith to know how many degree's your cooler will consume. That will vary depending on the ambient temp. Disable that, put in water slightly hotter than you need, and stir it down to the correct mash in temp.

I wouldn't necessarily disable the feature. BeerSmith is good at getting you pretty darn close to the temp you need if you set it up right. You just need know your system (which will come with time) and\or to be ready to adjust.
 
I wouldn't necessarily disable the feature. BeerSmith is good at getting you pretty darn close to the temp you need if you set it up right. You just need know your system (which will come with time) and\or to be ready to adjust.

Lets say you brew today and its 40F outside... then you brew tomorrow and its 70F outside. That difference could easily throw you off a degree or two.

I have done two AGs so far and have had to decoct all mash long. My guess would be 6 decoctions per mash. It seems every time I check the temp is around 147, so I drain 1/2 gallon boil it then mix in.

What kinda mash tun are you using that loses that much heat?
 
I have done two AGs so far and have had to decoct all mash long. My guess would be 6 decoctions per mash. It seems every time I check the temp is around 147, so I drain 1/2 gallon boil it then mix in.

To be safe, make sure you pull a decoction, which is the thick part of the mash, not drain the runnings and boil it. Most of the enzymes become dissolved in the water when mashing, and although a slight risk, you may denature too many of them and suffer poor conversion.
 
Lets say you brew today and its 40F outside... then you brew tomorrow and its 70F outside. That difference could easily throw you off a degree or two.

Beersmith allows you to set both grain temp and mashtun temp. If your mashtun is outside, its temp is the same as the outside temp. Ditto for grain. Having punched in these #s, and having set your heat capacity correctly for the tun, the math DOES work. It's basic science...no voodoo.
 
Beersmith allows you to set both grain temp and mashtun temp. If your mashtun is outside, its temp is the same as the outside temp. Ditto for grain. Having punched in these #s, and having set your heat capacity correctly for the tun, the math DOES work. It's basic science...no voodoo.

What method are you using to determine the specific heat of your mash tun? Or are you just choosing 0.300 for plastic?

There are many variables that go into determining necessary strike water temp. You are certainly correct in saying that the mash tun material temp equals ambient air. Since Beersmith knows the other variables (grain volume, deadspace volume) the only other variable is that specific heat.

In my case, I use the 0.3 for plastic, and I certainly input the correct temps, yet I never hit anywhere near my temps, always too low. Pre-heating the tun yields the same results. This has lead me to the determine that the igloo cube absorbs far more heat initially than beersmith thinks a cooler does.
 
What method are you using to determine the specific heat of your mash tun? Or are you just choosing 0.300 for plastic?

There are many variables that go into determining necessary strike water temp. You are certainly correct in saying that the mash tun material temp equals ambient air. Since Beersmith knows the other variables (grain volume, deadspace volume) the only other variable is that specific heat.

In my case, I use the 0.3 for plastic, and I certainly input the correct temps, yet I never hit anywhere near my temps, always too low. Pre-heating the tun yields the same results. This has lead me to the determine that the igloo cube absorbs far more heat initially than beersmith thinks a cooler does.

Have you tried adjusting the .3 number? I bet you could tune it so it works for your cooler.
 
Beersmith allows you to set both grain temp and mashtun temp. If your mashtun is outside, its temp is the same as the outside temp. Ditto for grain. Having punched in these #s, and having set your heat capacity correctly for the tun, the math DOES work. It's basic science...no voodoo.

Word! The only time I've been more than a few deg off was when I forgot to adjust those settings in BS. Like I said, if you set it up right, BS is good at getting my temps close.

What method are you using to determine the specific heat of your mash tun? Or are you just choosing 0.300 for plastic?

There are many variables that go into determining necessary strike water temp. You are certainly correct in saying that the mash tun material temp equals ambient air. Since Beersmith knows the other variables (grain volume, deadspace volume) the only other variable is that specific heat.

In my case, I use the 0.3 for plastic, and I certainly input the correct temps, yet I never hit anywhere near my temps, always too low. Pre-heating the tun yields the same results. This has lead me to the determine that the igloo cube absorbs far more heat initially than beersmith thinks a cooler does.

So it looks like you are getting consistent data and that BS is consistently off. I would just keep it in the back of my mind that I need to go x deg higher than what BS tells me and not rely on the program as much. it obviously cant take into account the specific heat of the specific cooler you are using...unless there is a setting somewhere I haven't noticed.
 
Word! The only time I've been more than a few deg off was when I forgot to adjust those settings in BS. Like I said, if you set it up right, BS is good at getting my temps close.



So it looks like you are getting consistent data and that BS is consistently off. I would just keep it in the back of my mind that I need to go x deg higher than what BS tells me and not rely on the program as much. it obviously cant take into account the specific heat of the specific cooler you are using...unless there is a setting somewhere I haven't noticed.

Yea man - I know how much i need to add to Beersmith's suggestion from experience like you said, I was just commenting on the fact that i need to stray from what BS suggests, and wondering if I could change that. You can change the specific heat in BS...
 
What method are you using to determine the specific heat of your mash tun? Or are you just choosing 0.300 for plastic?

There are many variables that go into determining necessary strike water temp. You are certainly correct in saying that the mash tun material temp equals ambient air. Since Beersmith knows the other variables (grain volume, deadspace volume) the only other variable is that specific heat.

In my case, I use the 0.3 for plastic, and I certainly input the correct temps, yet I never hit anywhere near my temps, always too low. Pre-heating the tun yields the same results. This has lead me to the determine that the igloo cube absorbs far more heat initially than beersmith thinks a cooler does.

For me, 0.310 works. It takes a few tries, but say you are consistantly undershooting your mash temp. This means tun specific heat is higher than 0.3, so bump it up to 0.350 or something and try again.

Easiest is to make a batch and record everything. Afterwards, go into beersmith, keep strike temp the same, and adjust specific heat until mash temp is the same as what you got.

I.e. say you are shooting for 154F mash. Beersmith says "add at 166F". You do, but hit 149 instead of 154. Go back into beersmith and adjust specific heat and target mash temp until it says 166F strike water gives you 149F mash. That's your correct specific heat now! Now you can put in your 154 mash temp, and it will say something like 169F strike water...which is what you will need in the future to hit that 154 temp with that recipe.
 
Bobby M has a vid on how to calibrate your setup for use in plugging in factors into your software.

[ame]http://www.youtube.com/user/BobbyFromNJ#p/u/2/5GnRlv8YzYs[/ame]
 
:mad:
For me, 0.310 works. It takes a few tries, but say you are consistantly undershooting your mash temp. This means tun specific heat is higher than 0.3, so bump it up to 0.350 or something and try again.

Easiest is to make a batch and record everything. Afterwards, go into beersmith, keep strike temp the same, and adjust specific heat until mash temp is the same as what you got.

I.e. say you are shooting for 154F mash. Beersmith says "add at 166F". You do, but hit 149 instead of 154. Go back into beersmith and adjust specific heat and target mash temp until it says 166F strike water gives you 149F mash. That's your correct specific heat now! Now you can put in your 154 mash temp, and it will say something like 169F strike water...which is what you will need in the future to hit that 154 temp with that recipe.

aha the old work backwards technique, i like it. great idea
 
IDK... this is a lot of fancy mathematics that can easily be solved by adding your strike water in a few degrees hot, and waiting 10 minutes for it to cool down, LOL!

Its like when people drive down the road staring at their GPS, drive right past a sign that tells them where to go, then follow incorrect directions based on old maps.
 
IDK... this is a lot of fancy mathematics that can easily be solved by adding your strike water in a few degrees hot, and waiting 10 minutes for it to cool down, LOL!

Its like when people drive down the road staring at their GPS, drive right past a sign that tells them where to go, then follow incorrect directions based on old maps.

The "fancy mathematics" can be done once and forgotten where as adding your strike water a few degrees hot every time and waiting 10 min is a constant effort each time you brew. Plus, wouldn't your "few degrees hot" be different every brew because recipes are different? So you would always be doing some math (maybe not "fancy") to figure out what temp you want.

I'm not saying your method is wrong by any means. It all comes out fine in the end. But for me, doing some adjustment or calculation once and setting it in a program so I dont forget and have to worry about it is the best solution.
 
I'm with sirsloop, the tun still takes time to reach a temperature equilibrium. I'm not comfortable with doughing in, the mash is 4 degrees hotter than I want and just "trust" that it will drop to where I need it in a few minutes. Temperature fluctuates where I keep my mash tun and I don't want to try and gauge it's temperature every time I brew. I just dump 175F water into my tun, mill my grain, come back to perfectly ready 170F for doughing in.

IMO, it's much more important to find the right strike water temp for your process than trying to play with other variables. Preheating the mash tun removes one of those variables and just makes it easier to be more consistent.

:off:
Hey sirs, what happened with the monster IPA?
 
Keep notes on brew day. Refer back to what you did , how you did it and how it came out. The more you brew the more you learn about your equipment and your technique. I even write down weather conditions, time of day and the like.
 
i always just make sure i have an extra 15 degrees on top of the mash water just to make sure i hit my target. i would much rather have to add ice cubes and stir for a minute than have to mess with boiling water/decoctions to raise the mash temp. i ususally mash in with 180-185*. btw, mashing outside when it's cold really messes with the cooler's ability to retain heat. normally i lose a degree, if that. not so if it's in the 30's! next time i'm mashing inside, losing 7-8* really sucks!
 
:off:
Hey sirs, what happened with the monster IPA?

Funny you mention it. I was just thinking about that brew yesterday. Monster IPA just had its 1yr anniversary. I moved recently which I'm sure stirred the crap out of it. Its had since like nov 15th to settle down in my basement untouched. Maybe I'll tap it up tonight and let you know.
 
Funny you mention it. I was just thinking about that brew yesterday. Monster IPA just had its 1yr anniversary. I moved recently which I'm sure stirred the crap out of it. Its had since like nov 15th to settle down in my basement untouched. Maybe I'll tap it up tonight and let you know.

It's still festering in the fermenter? I'm surprised the plastic hasn't dissolved yet. ;)
 
Back
Top