Mash tun temp stability problems

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ph0ngwh0ng

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Hi!

I've seen a thread on that some days ago, but I'm still at a loss.

I have bought a Coleman cooler (2 gallons) for small batches. The lid is not insulated (i couldn't find any cooler with an insulated lid at this size). I have tried aluminum foil and styrofoam and blankets, and tested with water at mashing temps. I still get a 10°F loss over an hour at best.

Now, I'm thinking about spraying the lid with insulating foam (polyurethane), but I'm unsure about the toxicity? There is a lot of water that condensates on the lid and drops back down in the mash...
 
If the spray foam can contact the wort, I would avoid using it.

Have your tried pre-heating the cooler? That should help a lot.

An alternative to the cooler might be to mash in a metal pot inside your oven using the oven to maintain mash temp. You can then run the grain through a strainer or colander to lauter.
 
Hi!

I've seen a thread on that some days ago, but I'm still at a loss.

I have bought a Coleman cooler (2 gallons) for small batches. The lid is not insulated (i couldn't find any cooler with an insulated lid at this size). I have tried aluminum foil and styrofoam and blankets, and tested with water at mashing temps. I still get a 10°F loss over an hour at best.

Now, I'm thinking about spraying the lid with insulating foam (polyurethane), but I'm unsure about the toxicity? There is a lot of water that condensates on the lid and drops back down in the mash...

have you actually used it to mash? or only tested with water?

testing with only water won't give you an accurate indication of how much heat you'll lose in a actual mash; you need a thermal mass (grains).
 
Have your tried pre-heating the cooler? That should help a lot.

This^^

You gonna lose a lot of heat of you're not precooling.

If you can't fill the lid with foam (Great Stuff is what it's called), maybe try wrapping an old sleeping bag or blanket or something to insulate the top. That's where the majority of your heat is going to go.

EDIT:

Oh looks like you did the blankets thing already.
 
How much airspace is there between the mash and the lid?

I had a similar issue because I bought a cooler large enough to mash 10 gallon batches. When I tried to do a 5 gal batch the airspace inside the cooler really sucked a lot of heat.

What I did was buy some hard board type house insulation. This pink board has an r value of 10. I cut a square that would fit inside the cooler. I wrapped this in a piece of heavy duty aluminum foil and made a quick rope handle to pull it out.

With this little contraption I can take up most of the airspace in the cooler. I only drop a few degrees over an hour.
 
What was the thickness of the styrofoam you used?

My mash tun is a cheapo cooler which I insulated and also cut me a fake lid of 2" styrofoam. The styrofoam (wrapped in food plastic) goes as far down into the cooler as I can get it without touching the mash. During the first brew I did with it (and one only one so far) I actually forgot put on the lid which came with the cooler, but even then I only lost about 1F during one hour.
 
If the spray foam can contact the wort, I would avoid using it.

Have your tried pre-heating the cooler? That should help a lot..

The foam would not contact the wort directly, but condensation would drip back in the wort.

Yes, all tests I run are with cooler pre-heating for 5 minutes. Then I take the temp and start the timer for 60 minutes.

testing with only water won't give you an accurate indication of how much heat you'll lose in a actual mash; you need a thermal mass (grains).

Yes, that was a concern during the tests. I have only tested with water with THIS cooler. The reason why I've begun tests is because I found out on my last batch that temp had dropped 15*°. I have since changed my cooler, because I noticed it lacked insulation around the faucet in an area of about 50 square inches, and it couldn't be fixed. But yes, i should test with an actual mash.

What I did was buy some hard board type house insulation. This pink board has an r value of 10. I cut a square that would fit inside the cooler. I wrapped this in a piece of heavy duty aluminum foil and made a quick rope handle to pull it out.

Ok yeah I should try this out. Although, I think I could just spray the foam on the lid, then cut a round plastic piece and glue it to the foam. That way, the water would condensate on the plastic, not the foam. Is this a good idea or not?
 
Preheat the cooler better! The first hot water addition really gets the heat sucked out of it, and so if you preheat the cooler with a gallon of 180 degree water (any hotter and the cooler will crack and warp), you'll lose almost no heat over the course of the mash.

Just preheat for at least 15 minutes, drain (or let the water go down to your strike temp and use it for your mash) and you'd be all set. A blanket over the top might help not lose so much heat from the top, but I think the cooler is sucking out the heat via the sides/insulation if you're only preheating for a quick 5 minutes. You need to preheat until the temperature stops dropping.
 
Preheat the cooler better! The first hot water addition really gets the heat sucked out of it, and so if you preheat the cooler with a gallon of 180 degree water (any hotter and the cooler will crack and warp), you'll lose almost no heat over the course of the mash.

Just preheat for at least 15 minutes, drain (or let the water go down to your strike temp and use it for your mash) and you'd be all set. A blanket over the top might help not lose so much heat from the top, but I think the cooler is sucking out the heat via the sides/insulation if you're only preheating for a quick 5 minutes. You need to preheat until the temperature stops dropping.

Been there, done that... No good. I really think the lid is the problem here. It gets quite hot, even with 3 blankets, i can still feel the hear through em, while the sides and bottom do not feel warm. I've wrapped the faucet too, since it got quite hot.
 
This is just a thought, and might be worth trying. I've used a ton of Great Stuff and even bought bottles of the stuff to mix up myself to make a myriad of things.

Take your cooler, close the lid on it, then drape some good vapor barrier plastic over top of it. I've always called the stuff visqueen. Make sure it completely covers the cooler and drapes down and past the cooler. Then use the great stuff (wear rubber gloves) and go all over the plastic, building up a nice solid surface. Let that cure. Because of the plastic underneath, you should be able to lift it off and just use it as a cap to put back on after you mash in. Keep in mind you are going to want to remove it, so be careful around the handle area so you don't permanently encase your cooler.
 
This is just a thought, and might be worth trying. I've used a ton of Great Stuff and even bought bottles of the stuff to mix up myself to make a myriad of things.

Take your cooler, close the lid on it, then drape some good vapor barrier plastic over top of it. I've always called the stuff visqueen. Make sure it completely covers the cooler and drapes down and past the cooler. Then use the great stuff (wear rubber gloves) and go all over the plastic, building up a nice solid surface. Let that cure. Because of the plastic underneath, you should be able to lift it off and just use it as a cap to put back on after you mash in. Keep in mind you are going to want to remove it, so be careful around the handle area so you don't permanently encase your cooler.

Very good idea! :rockin:

I'm trying it as soon as I can and will report! About the handle, I'll just remove it. It's useless anyway.
 
You've obviously done a lot of water tests with the cooler. I say just brew something and see what happens. Then, you'll have an understanding of heat loss during a real mash, and you'll have the bonus of making beer. It's a win win.
 
Testing with water is an invalid test!

Water will not hold heat like a mash.

Stop testing and brew, keep a little boing water handy and work it out if you lose a little temp.
 
Testing with water is an invalid test!

Water will not hold heat like a mash.

Stop testing and brew, keep a little boing water handy and work it out if you lose a little temp.

Aaah the mysteries of thermodynamics...

Yes, keeping boiling water and raising the temp when it falls too low is a swell idea too. Although it's a pain having to monitor temp throughout mashing, and this will induce heat loss by itself...

I'll definitely make a foam hat for my cooler (see previous posts). The lid is way too thin. When it's done, I'll simply do a batch and monitor heat at the beginning and at the end of mash. If and only if there is still a problem (temp fluctuation > 5°F), I'll be adjusting temp during mash with boiling water for future batches.
 
I don't know exactly what you mean by foam hat, but if you're using spray foam insulation, I'd make sure it's food grade.

Truthfully, I think you're over analyzing the heat loss during the straight water tests. As pointed out, the tests with just water are not an accurate representation of heat loss during an actual mash. Brew a batch of beer and see what happens. We're talking about a one gallon batch in a two gallon cooler, no big deal.
 
Preheat the cooler better! The first hot water addition really gets the heat sucked out of it, and so if you preheat the cooler with a gallon of 180 degree water (any hotter and the cooler will crack and warp), you'll lose almost no heat over the course of the mash.

Just preheat for at least 15 minutes, drain (or let the water go down to your strike temp and use it for your mash) and you'd be all set. A blanket over the top might help not lose so much heat from the top, but I think the cooler is sucking out the heat via the sides/insulation if you're only preheating for a quick 5 minutes. You need to preheat until the temperature stops dropping.

Going to try this "overheat" preheat step when mashing really small grain bills in the 5 gallon cooler.
 
I was running into the same problem and was going to check out the "great stuff" solution that others have brought up. But never got around to it....in the meantime I ran into an issue with my "root cellar" in my basement this past winter where I finally decided to try a radiant barrier solution on the door there. A thought occurred to me that perhaps the same thermodynamical (yes, I just made that word up) principles might apply...so I cut a circle out and added it to my lid. I've only used it once (this past weekend in fact) and it worked remarkably well. The super-hot lid you had mentioned earlier is exactly what I had dealt with previously. This time? Couldn't tell I had anything hot inside at all. So, it worked for me.

I attached a pic with the hopes it could help.

It isn't secured with anything. I just made it large enough that it would sit in the lid and stay there; screwed it on the tun, and popped it off when done so it could dry off due to the condensation.

This is what I used: http://www.homedepot.com/p/t/100020...&productId=100020855&R=100020855#.UdoS3fm1E4o

IMG-20130707-00207.jpg
 
^ THIS

I saw a video on YouTube (think it was Bobby M) and the used that Reflectix stuff to wrap around his keggle mash tun as well as circular pieces just like that to put on top.

That stuff is no joke!! Holds heat well.
 
Going to try this "overheat" preheat step when mashing really small grain bills in the 5 gallon cooler.

Trust me! After all, the internet is always a truthful place. :cross:

Seriously, it works. Totally. It takes about 15 minutes for the temperature to equalize, but if you take the temperature when you add the water at 180 degrees, and then like 8 minutes later, the temperature will be in the low 160s. Even in warm weather, the plastic and insulation "suck out" that much heat. It's unbelievable until you do it yourself! After that huge temperature drop, the cooler will hold heat within 1 degree for an hour, even without an insulated lid (or ANY lid). Try it! It's one of those things that is weird, but really works.
 
Trust me! After all, the internet is always a truthful place. :cross:

Seriously, it works. Totally. It takes about 15 minutes for the temperature to equalize, but if you take the temperature when you add the water at 180 degrees, and then like 8 minutes later, the temperature will be in the low 160s. Even in warm weather, the plastic and insulation "suck out" that much heat. It's unbelievable until you do it yourself! After that huge temperature drop, the cooler will hold heat within 1 degree for an hour, even without an insulated lid (or ANY lid). Try it! It's one of those things that is weird, but really works.

I did. It doesn't. Would like to. But nope... Works with 5 gal batches in my other cooler but not that one. As I'm doing small batches as experiments before going 5 gal scale, I want the two collers to reproduce the same conditions. Heat loss is constant at 3°F per 15 minutes, however how long I wait. Preheating is a must for me, and have always done so by preheating the water to 180°, waiting, then flushing to desired volume, and waiting for strike temp to come. Maybe I'll try the thermal barrier thingy. Hey, I brew the Bobby M way, so why not insulate the Bobby M way too.
 
The more I think and research on the subject, the more I think the reflexive stuff is better. Ployurethane foam RESISTS to heat transfer, it therefore ABSORBS heat very well, without transferring it to the otehr side (outside of the tun). But reflexive coating REFLECTS heat back in the mash tun. Can't wait to try this out tomorrow. :D
 
I tried the reflexive bubble wrap this morning with the evil water test from hell and it works great! 2.5°F loss in an hour, as opposed to 10°F minimum for other insulating methods. Yay!
 
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