Having trouble with mash tun heat loss.

[jdgabbard]

M having a little problem with my mash tun loosing heat, or at least I'm thinking that is the source of the problem. And hope you guys can give me some insight as to what I can do to remedy the problem.

I'm getting lower than expected pre-boil and post boil gravities. Beens that should be coming to about 1.050, are only getting to about 1.040. And I'm sure it's a problem with efficiency. I have a 1/2" nps kettle style thermometer installed in the front of the tun (a 12.5g cooler), and I mash, usually, for 90 mins.

The problem is that I monitor the temps, and it seems as tho the temp is falling off very quickly, as after about 30 minutes the temp is reading about 140F. When I originally started with a temp of about 152-154. I'm pretty sure it's mostly from the size of the tun, and the loss of heat within. Anybody else experience these kind of problems? Should I just elect to go with a smaller cooler?

 

[RC0032]

Do you preheat the mash tun?

 

[RoKozak]

Preheating is a must. Is your strike water a higher temperature than the mash temp so that when the grain is added you can get the temp regulated down to where you need it? I have had issues with it dropping 4-6 degrees in a 10 gallon cooler, but never 12-14. Mine was primarily due to lack of pre-heating. You can also try adding some Styrofoam on the lid of your cooler to keep heat in.

 

[feinbera]

If your real goal is to diagnose your poor efficiency, you could try maintaining the temperature by adding a quart or two of boiling water a couple times during your mash.

It's more of a kludge than a long-term solution, but it won't be so bad for just a batch or two, and it will answer the question "are my efficiency troubles due to mash temperature loss" before you spend a lot of time and/or money fixing an issue that may or may not be the root cause of your problem.

 

[FuzzeWuzze]

If your real goal is to diagnose your poor efficiency, you could try maintaining the temperature by adding a quart or two of boiling water a couple times during your mash.

It's more of a kludge than a long-term solution, but it won't be so bad for just a batch or two, and it will answer the question "are my efficiency troubles due to mash temperature loss" before you spend a lot of time and/or money fixing an issue that may or may not be the root cause of your problem.

Be careful doing this though, i know that the rubbermaid 10g coolers dont like water going in above like 190...when you pour it in you can hear the insulation crack..my inner skin already started to break away at the top of the cooler due to this presumably expansion and contraction from the high heat...it still works 100% ...just be careful they arent meant to hold boiling water.

 

[Irish13]

I use a Rubbermaid cooler 10gallon. What I do is preheat with 100 degree water drain it, bring the water up to about 170 dump it back in. Then I dump my grain bill making sure there aren't any cool pockets. The stationary thermometer which you have is nice, but it only checks the temp in one area. I use a stab in thermometer and check the temp in multiple areas to make sure there aren't any cold spots. If the mash water is lower then where it needs to be then I'll dump in more water at 180 or so and mix in.

 

[jdgabbard]

Yeah, I haven't been preheating. I'll try that this time. I'll bring the water up to 150ish and throw it in there while bringing my strike water to temp.

 

[BrewinHooligan]

Another way to preheat that works good for me is to heat my strike water 10 degrees higher than I want. Then I let the temp drop to 1 or 2 degrees higher than I want, then dough in and stir until I hit my desired temp and close it up for 60-90 minutes with very little heat loss.

 

[duckredbeard]

I don't preheat my mash tun. I do take a temperature reading of my grain, which has been in a paper bag inside a sealed bucket. I usually purchase and mill the grain about 4-5 days prior to brew day. The grain is kept in the same room for that time until brew day. I don't even take it outside until I'm ready to mash in. I use a strike temp calculator to estimate my temp. Then, based on experience (and a little seat-of-the-pants flying) I add 3-4 degrees to compensate for mash tun heat absorption. I always note my grain temp, calculated strike temp, actual strike temp, and initial mash temp. Hit my temps every time without preheating.

 

[Calichusetts]

Airspace is also an issue...air is a horrible insulator so if your taking the top off your cooler consistently to check, your also adding to that loss

 

[srmarcondes]

What about the gain size and mill opening? That can have a huge impact on the efficiency and lower your OG a bunch....

 

[tre9er]

I stopped preheating and instead fill my tun with about 185* strike water. I close the lid and do a few other things, checking every 5-10 minutes. When the temp of stirred water is a few degrees ABOVE my desired strike temp, I dough-in slowly, stirring like crazy, over the course of about 5 minutes of slowly adding grain. Usually the temp is a bit high, not to worry. I stir, stir, stir with the lid open and take readings every minute or so until it's just on the high side of where I want.

I usually don't lose even a degree over an hour and I have a massive 70qt cooler with tons of headspace. Stirring AS you dough-in and before running off are key elements to efficiency. I also mash thin, usually about 1.5qts/lb. of grain (I set it up to have the same amount of strike and sparge. Makes remembering volumes MUCH easier)

 

[RC0032]

Another way to preheat that works good for me is to heat my strike water 10 degrees higher than I want. Then I let the temp drop to 1 or 2 degrees higher than I want, then dough in and stir until I hit my desired temp and close it up for 60-90 minutes with very little heat loss.

I stopped preheating and instead fill my tun with about 185* strike water. I close the lid and do a few other things, checking every 5-10 minutes. When the temp of stirred water is a few degrees ABOVE my desired strike temp, I dough-in slowly, stirring like crazy, over the course of about 5 minutes of slowly adding grain. Usually the temp is a bit high, not to worry. I stir, stir, stir with the lid open and take readings every minute or so until it's just on the high side of where I want.

I usually don't lose even a degree over an hour and I have a massive 70qt cooler with tons of headspace. Stirring AS you dough-in and before running off are key elements to efficiency. I also mash thin, usually about 1.5qts/lb. of grain (I set it up to have the same amount of strike and sparge. Makes remembering volumes MUCH easier)

^ These.

 

[RoKozak]

I stopped preheating and instead fill my tun with about 185* strike water. I close the lid and do a few other things, checking every 5-10 minutes. When the temp of stirred water is a few degrees ABOVE my desired strike temp, I dough-in slowly, stirring like crazy, over the course of about 5 minutes of slowly adding grain. Usually the temp is a bit high, not to worry. I stir, stir, stir with the lid open and take readings every minute or so until it's just on the high side of where I want.

I usually don't lose even a degree over an hour and I have a massive 70qt cooler with tons of headspace. Stirring AS you dough-in and before running off are key elements to efficiency. I also mash thin, usually about 1.5qts/lb. of grain (I set it up to have the same amount of strike and sparge. Makes remembering volumes MUCH easier)

I'm a bit of a noob, but I've heard that mashing thin can push up your pH. Although, 1.5qt/lb doesn't actually seem that much thinner. I'm going to try this next time. It seems to just make sense.

 

[tre9er]

I'm a bit of a noob, but I've heard that mashing thin can push up your pH. Although, 1.5qt/lb doesn't actually seem that much thinner. I'm going to try this next time. It seems to just make sense.

I started doing this based on Denny Conn's recommendations. He's got about 750 batches under his belt and is fairly renowned.

I haven't done anything scientific to confirm things, but all I know is that I get 80% efficiency in my system, repeatable, and haven't noticed any tannins, etc.

 

[bighorn_brew]

Relatively, air is a good insulator.

 

[BrewinHooligan]

I started doing this based on Denny Conn's recommendations. He's got about 750 batches under his belt and is fairly renowned.

I haven't done anything scientific to confirm things, but all I know is that I get 80% efficiency in my system, repeatable, and haven't noticed any tannins, etc.

I started mashing at 1.5 qt/lb recently for the same reasons and also noticed I get better efficiency doing so (not HUGE, but about 3-5% better) averaging 75% now.

 

[william_shakes_beer]

If you're using a cooler as a mash tun, check to see if there is insulation in the lid. Some are hollow, since they are built for cold, not hot. If hollow, try filling with touch-n-foam through a little port hole.

 

[tre9er]

If you're using a cooler as a mash tun, check to see if there is insulation in the lid. Some are hollow, since they are built for cold, not hot. If hollow, try filling with touch-n-foam through a little port hole.

Ah, yes. I neglected to mention that I also cover my cooler with two blankets...another good suggestion.

 

[grimstuff]

+1 on preheating.... ALSO, I have noticed that smaller beers, like around 1.045 OG, tend to lose more heat than bigger beers. I attribute this to less thermal mass from a smaller grain bill and fluid.

 

[sonex]

I'm a bit of a noob, but I've heard that mashing thin can push up your pH. Although, 1.5qt/lb doesn't actually seem that much thinner. I'm going to try this next time. It seems to just make sense.

I have heard it could add tannins. But from my experience its not true. I mash in up to 2qt/lb and never had any issues. I shoot for equal amount into the kettle from my first and second runnings to maximize efficiency. brew in the bag brewers mash in at much higher ratios with out issues.

 

[jdgabbard]

Yeah, the lid has insulation. I this the airspace is the issue with the heat, combined with the cooler needing to draw the heat in. I think preheating will probably solve the problem. If not I'm going to go with a smaller cooler. But hopefully after I try the next batch all will be regulated better. I'd like to get a better efficiency. But who knows, maybe I just need to up my grain bill....