How do YOU keep your cooler mash-tun as close to temp as possible?

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.
In Florida, this is not much of an issue. I get my temp locked in and close the lid. I usually only lose about 1 degree.

Now, on the issue of cooling, you up north have the upper hand. Choose your evil.
 
In my 10 gallon mash tun I usually only lose 1-2 ºF with preheating my tun and a folded up blanket over the lid. I've only done 2 batches so far in the 5 gallon tun I just built, but I lost about the same the first batch and this batch I brewed today I lost 5 ºF. I'm not sure what caused such a big drop this time. I think I will try the foil or maybe the insulation on top of the grain bed next time though.
 
what about those of us who are using a 15.5 gallon sanke as a mash tun? How are you keeping your mash at temp for 60 minutes?

I've got my sanke MLT wrapped with one of those cheap blue foam pads you put under a sleeping bag. It helps some but I still have to start out with a stiff mash and plan on adding boiling water a couple of times during the mash to keep in the neighborhood I want. My mashes generally fluctuate by 2 - 3 degrees. I try to start about a degree higher than my targeted average. I want to go to a herms setup to stabilize things but no pumps for now :(
 
So I had a big styrofoam box out in the garage. I cut a circle out of it big enough to fit snuggly inside my 10gal Home Depot Cooler Mash tun then wrapped it up in a food-safe bag and zip-tied it shut. The circle is probably about 2" thick and it is your typical white styrofoam used for packing or as disposable coolers.

Brewed a Blonde with just 9lbs of grain. Grain + Water took up less than 1/2 of the space in the tun. I had recently discovered I was losing a lot of heat on small beers like that (9 degrees on my last one). With my styrofoam circle resting just above the grain bed I lost less than 1 degree. Nothing changed in my pre-heating or dough-in methods, everything was exactly the same other than the, I guess you would call it a false-top.
 
opiate82 said:
So I had a big styrofoam box out in the garage. I cut a circle out of it big enough to fit snuggly inside my 10gal Home Depot Cooler Mash tun then wrapped it up in a food-safe bag and zip-tied it shut. The circle is probably about 2" thick and it is your typical white styrofoam used for packing or as disposable coolers. Brewed a Blonde with just 9lbs of grain. Grain + Water took up less than 1/2 of the space in the tun. I had recently discovered I was losing a lot of heat on small beers like that (9 degrees on my last one). With my styrofoam circle resting just above the grain bed I lost less than 1 degree. Nothing changed in my pre-heating or dough-in methods, everything was exactly the same other than the, I guess you would call it a false-top.
.
That's what I do. I got a few sheets of styrofoam from lowes and cut to fit inside my round cooler, And it rests right on top of the mash.
 
Brewed a small batch yesterday (17lbs grain bill) and I held my temp. over a 60 min mash to only 1 degree loss. I made my insulation wrap, put a blanket on top of it and brought it into the house. Win in my book! I forgot the aluminum foil until it was too late. Thanks for the advice from so many people, LOVE THIS SITE!
 
Try putting aluminum foil on top of the mash.
I switched from a 10 gallon to a 7 gallon water cooler and there is a minimum of space between mash and lid.. 3-4 inches of air doesn't allow much heat to dissipate into the air. Lose 1 degree if that and I stir mash every 15 minutes over 60 minutes.
 
I just shoe-horned a Bayou Classic kettle into a round cooler.*



NewMashTun01_zpse428e9b4.jpg



Last few batches I did I may have lost from .5F-1.0F in a 60 min mash.


* idea from member Ben the Brewman



EDIT: I really don't understand how these cooler manufacturers aren't considering this idea of going with a stainless liner. If I thought I could buy a 15 gallon cooler, round or rectangular, with a stainless liner, I'd buy right now.
 
I placed 1/4" ridged foam (left over from my fermentation chamber build) over the mash. Prior to that I would lose 5degF during a 60 min mash. Now I might change 1degF. Oh and I have a huge mash tun and it works the same with 5 Gallon batches too

View attachment 1428211416490.jpg
 
I've learned to become less anal about the whole brew process. If it's a batch with little heads pace or its hot outside I done worry about it. If it's cold out or I'm brewing a 1.045 beer I'll mash a degree or two higher to account for temp loss.
 
I have been brewing for years and have since gone to AG a few years ago but have never been able to hold my mash-tun AT temp. In the pas I have just accounted for the 2-3 degrees that I lose so if I need to hold 153 I'll mash at 156. I am using a cooler as my mash-tun and thought of using a fermentation band(for a bucket) or even plugging in a heater blanket and just wrap it like a baby. That just gave me another idea, heating pad under the cooler should help too... I might try the heating pad and heated blanket this weekend and see how it does. I'll keep you posted on the outcome. BTW, I'm talking about when it gets cold outside(as I brew in my garage that isn't heated).

How do you keep your temp. close?

Thanks for any ideas! :tank:

I use a Home Depot round cooler. I preheat the tun by filling with tap water, right now it is about 110 degrees. I empty that just before I add my strike water. After adding grain using BeerSmith, my temps are within 1/2 degree, it usually raise 2 more degrees and with lid on will stay at that temp for the full hour even when I brewed this winter at 35 degree ambient temp.
The key is preheating the tun so it does not cool off during the mash.
 
I haven't had any trouble with heat loss whatsoever. I have a 62 qt Coleman Extreme cooler. I pre-heat it for about 20 minutes, add mash water, dough in, and close it. I have done 6 beers like this so far and the most heat loss I have experienced is 1 degree over a 60 minute mash.

And also, I seriously doubt that losing 2 degrees over the course of a 60 minute mash is going to affect the beer whatsoever.
 
Don't forget, as I have stated before, pour your strike water at 5 to 10 degrees warmer than your target temperature and then let it cool to your target before adding grains.
 
Don't forget, as I have stated before, pour your strike water at 5 to 10 degrees warmer than your target temperature and then let it cool to your target before adding grains.

If mash tun has not been preheated all of that cold surface will pull temps down several degrees. Learned from experience ( the hard way).
 
I just shoe-horned a Bayou Classic kettle into a round cooler.*



NewMashTun01_zpse428e9b4.jpg



Last few batches I did I may have lost from .5F-1.0F in a 60 min mash.


* idea from member Ben the Brewman



EDIT: I really don't understand how these cooler manufacturers aren't considering this idea of going with a stainless liner. If I thought I could buy a 15 gallon cooler, round or rectangular, with a stainless liner, I'd buy right now.


What size cooler and pot did you use?
 
The cooler is the typical Home Depot 10 gallon. The pot was a Bayou Classic. It's just a generic kettle with no volume markings, etc. I drilled the hole for the spigot. I believe the pot model is the 1044.


Thank you
 
I appreciate forum discussions with lots of constructive ideas and support. I, too, have struggled with maintaining mash temps in my 5 Gal Gott MLT, but I am starting to realize/wonder that my anxiety to maintain mash temp over 60 min is born more from my competitive nature and tendency to conform to convention than based on what is really necessary.

FWIW, I too preheat my MLT to 110-120* with hot water while I bring my strike water to temp. This serves to give my HLT & MLT one more rinse and I use this time to prepare other steps or processes. I, too, keep grains inside close to 70* and wrap my MLT after dough in. Foil and Styrofoam seem like they would work well. I do agree that dough in should be done as quickly as possible. I also think overshooting strike water temp into MLT and allowing to cool to strike temp is a good idea as water will cool during transfer from HLT to MLT from hoses, air, and MLT absorbing some of the heat from the strike water.

My last brew day, I made a Nelson clone and pushed my MLT to it's limit with a fine mill and a thick mash. I intentionally overshot initial strike by 1*, but at 15 min intervals stirred and noticed rapid temp loss (1-1-1/2* every 15 min).

As Zymurgist suggested previously, and as demonstrated by the poster in the link below, conversion of today's modified grains actually takes place in the first 5-15 minutes of the mash assuming proper crush and water to grain ratio.

https://www.homebrewtalk.com/f244/mas...5/#post6750563

The real issue regarding maintaining mash temp, as I see it, is not about fully converting starches to sugars to hit predicted OG targets, but breaking down the correct sugar branches to hit target attenuation and FG while still obtaining the right body and flavor for a given recipe. So the question I'm struggling with, after the first 15 minutes at target temp, what is happening the remaining 45 min during mash, and how necessary is this to conversion, flavor, and body?

More and more, I am beginning to question the time my typical brew day takes and looking for ways to be both more efficient while reducing time for certain steps. I think the first 15 minutes of Mash temp is crucial, but the remaining time is just there to vex our never ceasing desire to tinker and fuss over 1* to 2*.

I also have struggled with reliability of thermometers. I have 5 different thermometers (2 digital, 2 glass, 1 bimetal) having calibrated the digital and bimetal. I have done tests where all 5 report different temp +/- 2-3* at various temp ranges. So here is another variable where despite my need to control, I am at the mercy of my equipment. Don't know if I can justify the $100 for the Thermopen, which is supposed to be the best. Don't know if $100 investment would even matter...
 
1. i heat my strike water to around 175-180 then pour it in my mash tun and close the lid. I let it sit for a while to preheat.
2. Then i open the lid and stir the water around until it settles at a degree or two above what beersmith tells me my mash in temp is.
3. mash in and stir until I am at my mash temp
4. Then i put a piece of aluminum foil on the grain bed. Close the lid and cover with a blanket.

My cooler is a typical run of the mill cooler that I bought off craigslist for 15 bucks. The lid is hollow and not insulated, in fact it has a little door built in to the lid that you can use to reach in and grab a brew.

I don't even lose a degree over a 60 minute mash this way.
 
I BiaB and mash directly in my kettle. Heat the water to temp, mash in, double check I am at the proper mash temperature. In the winter time or anything below about 70F, I'll cover the whole thing with a thick towel. Generally every 20 minutes for the hour I stir it up and kick the burner back on for 60 seconds.

This generally seems to keep the temperature within about 2F of what I am looking for. In the summer time I don't even bother to cover it up. In the sun and with temps of 80+F, If I kick the burner on once for a minute during an hour mash it generally stays within 1-2F.

Of course in the dead of winter brewing in my garage there are times I cover it up and if I forget about it for half an hour because I am busy doing other things, I can come back and it has dropped 5-6F and I have to fire the burner for 2-3 minutes stiring it up to get it back to the proper temperature.

I generally take the temp loss in to account, so I'll tend to mash high by 2F or so in the winter time, because I know it might drop from, say, 154F to 150F in 20-30 minutes covered up, before I kick it back up to temp.
 
I appreciate forum discussions with lots of constructive ideas and support. I, too, have struggled with maintaining mash temps in my 5 Gal Gott MLT, but I am starting to realize/wonder that my anxiety to maintain mash temp over 60 min is born more from my competitive nature and tendency to conform to convention than based on what is really necessary.

FWIW, I too preheat my MLT to 110-120* with hot water while I bring my strike water to temp. This serves to give my HLT & MLT one more rinse and I use this time to prepare other steps or processes. I, too, keep grains inside close to 70* and wrap my MLT after dough in. Foil and Styrofoam seem like they would work well. I do agree that dough in should be done as quickly as possible. I also think overshooting strike water temp into MLT and allowing to cool to strike temp is a good idea as water will cool during transfer from HLT to MLT from hoses, air, and MLT absorbing some of the heat from the strike water.

My last brew day, I made a Nelson clone and pushed my MLT to it's limit with a fine mill and a thick mash. I intentionally overshot initial strike by 1*, but at 15 min intervals stirred and noticed rapid temp loss (1-1-1/2* every 15 min).

As Zymurgist suggested previously, and as demonstrated by the poster in the link below, conversion of today's modified grains actually takes place in the first 5-15 minutes of the mash assuming proper crush and water to grain ratio.

https://www.homebrewtalk.com/f244/mas...5/#post6750563

The real issue regarding maintaining mash temp, as I see it, is not about fully converting starches to sugars to hit predicted OG targets, but breaking down the correct sugar branches to hit target attenuation and FG while still obtaining the right body and flavor for a given recipe. So the question I'm struggling with, after the first 15 minutes at target temp, what is happening the remaining 45 min during mash, and how necessary is this to conversion, flavor, and body?

More and more, I am beginning to question the time my typical brew day takes and looking for ways to be both more efficient while reducing time for certain steps. I think the first 15 minutes of Mash temp is crucial, but the remaining time is just there to vex our never ceasing desire to tinker and fuss over 1* to 2*.

I also have struggled with reliability of thermometers. I have 5 different thermometers (2 digital, 2 glass, 1 bimetal) having calibrated the digital and bimetal. I have done tests where all 5 report different temp +/- 2-3* at various temp ranges. So here is another variable where despite my need to control, I am at the mercy of my equipment. Don't know if I can justify the $100 for the Thermopen, which is supposed to be the best. Don't know if $100 investment would even matter...

I've done very, very basic calibration checking on my candy thermometer that I use. It seems to be within around 1F at boiling temperatures (It reads 212.3F, but at my altitude it should be about 211F)) and about 2F at freezing (ice water reads about 34F). I figure that is close enough. I've only checked it once since I initially checked it (maybe 9 months after the fact?) and it seems to be more or less holding at that.

So, until the thing breaks, I'll periodically check its calibration maybe once a year to make sure I am not starting to get a large drift. Then, I figure meh, if it is off by a degree or two, no big deal. The fact that I am using it for everything brewing is all that really matters.

On the fermentation side, I haven't bothered calibrating my ITC1000 and STC1000, but I DID compared the thermocouples of the two, they read within .2C of each other. Which is all that really matters to me, so that I know if I dial in one temperature on one of my minifridges, then I should be getting the same fermentation temperature as I would be on the other minifridge, within some tiny margin of error based on the differences in minifridges (3.5 vs 4.4cu-ft), but the actual temperature control should be doing the same thing.
 
2 things about coolers as mash tuns...

Heat goes up. The lids on these things are hollow. That's where the heat is getting out. Get a can of that spray insulation from Home Depot or Lowe's and spray the lid full.

The other thing I've found with mine is that the lid seals well until steam pressure builds up inside the cooler and it creeps up and loses the seal. I put a few pound weight on the lid during the mash.

These two things brought my losses down to within 1 degree. I can live with that. I will try the foil trick though!
 
I just shoe-horned a Bayou Classic kettle into a round cooler.*



NewMashTun01_zpse428e9b4.jpg



Last few batches I did I may have lost from .5F-1.0F in a 60 min mash.


* idea from member Ben the Brewman



EDIT: I really don't understand how these cooler manufacturers aren't considering this idea of going with a stainless liner. If I thought I could buy a 15 gallon cooler, round or rectangular, with a stainless liner, I'd buy right now.


Your way is cheaper, but still: https://www.kickstarter.com/projects/958078058/chapman-homebrew-equipment-mash-tuns-fermenters-ke
 
I just step mash all of my beers and use separate beta and alpha rests. If I'm doing a beta rest at 145, it doesn't really matter if I end up at 147. If I'm doing an alpha rest at 160, it doesn't matter much if it ends up being 158 or 162. To control fermentability, I mash for a longer or shorter time at the beta temperature. I find time easier to control than temperature.
 
1. i heat my strike water to around 175-180 then pour it in my mash tun and close the lid. I let it sit for a while to preheat.
2. Then i open the lid and stir the water around until it settles at a degree or two above what beersmith tells me my mash in temp is.
3. mash in and stir until I am at my mash temp
4. Then i put a piece of aluminum foil on the grain bed. Close the lid and cover with a blanket.

My cooler is a typical run of the mill cooler that I bought off craigslist for 15 bucks. The lid is hollow and not insulated, in fact it has a little door built in to the lid that you can use to reach in and grab a brew.

I don't even lose a degree over a 60 minute mash this way.

I did this in Friday and it worked great!


Beginning temp
View attachment ImageUploadedByHome Brew1428950528.275669.jpg

Foil on
View attachment ImageUploadedByHome Brew1428950771.873645.jpg

After 60 minutes, this was the lowest after checking multiple spots
View attachment ImageUploadedByHome Brew1428950713.794897.jpg

Thanks for the tip. I even forgot to cover with a blanket.
 
This is a great thread on a good topic, and has helped me immensely, since moving out of the kitchen into the garage. Things I've taken away from this thread, that definitely made a difference are the following:

I fold a blanket and wrap it around my 10 Gallon Igloo MT, and secure it with bungee cords, tucking a large section over the top and into the sides.

I think smaller quantities of water heat faster, so I get 3 gallons to 180 and use this to preheat the MT.

I heat another 4 gallons while the MT heats, then empty the MT back into the kettle and heat to about 168. This is where I mash.

I cut a 2" thick false top out of a disposable styro cooler lid, and float this on top of my mash (thanks opiate82).

My first time out I had trouble maintaining over 142F. Now (in a 52F garage) I have to stir my temps down, and lose about 1F/hr.

Thanks to all for this advise.
 
I use an Igloo cube cooler and to be quite honest I have used many of the tricks outlined in this thread such as preheating the tun, putting aluminum foil over the mash, covering the outside of the cooler with an insulating material and when doing those I almost always stay right on my target temp for the entire mash. However, truth be told I generally gain^H^H^H^H lose only 2 degrees over the course of a 60 minute mash by doing absolutely nothing extra.

My palate is not refined enough to tell the difference between a beer mashed at exactly 149 versus one that started at 149 and ended up at 151^H^H^H 147 over the course of an hour so I just don't worry about doing those extra procedures at all. If I remember to, then breaking out the aluminum foil is pretty easy so I'll do that one but if I forget, its no big deal. YMMV.
 
However, truth be told I generally gain only 2 degrees over the course of a 60 minute mash by doing absolutely nothing extra.

I hope you mean lose 2 degrees. If you are saying you gain 2 degrees you must have flunked your science class. It is impossible to gain temp without some source of energy. If you are gaining temp without energy you should call the government because you have just found a new source of energy. Maybe you can cure global warming.

You just are not stirring enough before you take your temp. Then when the temp stabilizes that is the true temp.
 
I preheat my Igloo 10 with hot water, then shoot for a few degrees over figuring I can stir and cool down, but heating back up isn't an option unless I add boiling water - which i do sometimes from an electric tea kettle.

I was losing a lot of heat from the lid so I drilled it and shot it full of expanding foam. It holds much more constant now. Having the mash tun in the warm house as opposed to the cold garage helps too, and if nothing else I can wrap some reflectix around it.
 
For the past year I've been using a Mini E-HERMS system to keep my mash right at temp. It's a combination of a mini HERMS coil. a temp controller, cooler and pump. I couldn't be more happy with my current set up for the simple reason that it didn't cost me a fortune to keep my mash at the right temp. I've noticed a great improvement of my beers and the repeatability has increased as well. I got the idea from the $50 Herms thread that's on this site. Helped me greatly!
 
My old rectangle cooler was a champ. I would pre-heat with hot water, let it sit for 15 min or so, and then dough in at the appropriate temp. Never lost more than 2 degrees. Never covered with blankets or anything. Just kept it inside the house in the winter, and didnt have to do much in the summer. My buddy uses it now, and has the same experience.
 
I hope you mean lose 2 degrees. If you are saying you gain 2 degrees you must have flunked your science class. It is impossible to gain temp without some source of energy. If you are gaining temp without energy you should call the government because you have just found a new source of energy. Maybe you can cure global warming.

You just are not stirring enough before you take your temp. Then when the temp stabilizes that is the true temp.

Yes, I meant I lose 2 degrees.
 
Back
Top