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Keg Mash Tun Project

Ok guys hopefully this will be easy. I am tired of using my cooler as a tun and want to change things up a bit. I also want to have a system that is direct fired. So my question is heat retention related. What material could i insulate the outside of the keg with? What stands up best and where can I find it?

Using a keg for a direct-fired MT works, but you have to be diligent with your stirring to avoid scorching and/or boiling the wort in the area of the flame. If you’re using a braid, be sure it’s very short, like 2-3" (which is all you need anyway), or you’ll run the risk of hitting it while you are vigorously stirring. And if you are going to install a thermometer, get the short-stem version for the same reason.

For insulation, the aluminum-foiled bubble wrap works well, but you need to keep it away from the skirt area or it will melt when you add heat - cut a strip so that it covers the area six inches from the bottom to 4-6 inches from the top and it’ll do a good job.

FWIW, I went from a round cooler to a keg and then to rectangular coolers and I don’t miss the direct-fire option at all - simple infusions of boiling water do the same thing with a lot less effort.

A friend picked up some used kegs set up for mash tuns last winter and we’ve used them a few times and been disappointed each time. It is just so much more work than our coolers which we know exactly what to expect. Temperature fluctuates wildly and we had a really hard time keeping it where we wanted. It would drop so we would heat it up while stirring and then all the sudden it would jump like mad. Maybe we weren’t stirring hard enough? I don’t know…

All the beers turned out in the end, but the process was a PITA. If you want to do step up infusions you could always get a bigger cooler for a mashtun. Just something to think about. I’m sure if we took the time we could hone in the process, but I don’t want to. All that said, they do look cool!

I have seen where a lot of people use hot water heater insulation. Also, to avoid scorched grains you can use a false bottom. You can also do a RIMS system, which is indirect fired. I personally would not use a cooler because i have yet to see one that is actually rated for hot liquids (which means you gotta be leaching something out of the plastic).

[quote=“mppatriots”]I personally would not use a cooler because i have yet to see one that is actually rated for hot liquids (which means you gotta be leaching something out of the plastic).[/quote]Coolers are made from food-grade HDPE and are designed to keep food either hot or cold.

I would say direct me to a manufacturer’s website where it actually says that. I have searched and I have yet to find a site that backs up your claim.

Why don’t keg mashtuns hold heat . . . . .especially if you are doing 10 gallons in it? I have not used one, but I have a 9.5 gallon SS pot that I use as a mash tun. I bring about 5 gallons of water to about 165ish, dump in 10-15lbs of grain, stir well, settles in at 153ish, put the lid on and it won’t drop more than a degree or two in 60-75 minutes and I have no insulation.

I can understand if you are brewing outside in cold/windy weather, but under normal conditions, why is it so hard to hold temp with that much grain and water?

Just curious.

I would think water heater blanket would help as far as the insulating question.

[quote=“mppatriots”]I would say direct me to a manufacturer’s website where it actually says that. I have searched and I have yet to find a site that backs up your claim.[/quote]First hit on a search for “coleman cooler hdpe”:
http://www.reilleypromotions.com/coleman-coolers

And I was curious enough to send an enquiry to Coleman customer service earlier today asking them for temp ranges and composition. I’ll post their reply when I get one.

[/quote]First hit on a search for “coleman cooler hdpe”:
http://www.reilleypromotions.com/coleman-coolers

And I was curious enough to send an enquiry to Coleman customer service earlier today asking them for temp ranges and composition. I’ll post their reply when I get one.[/quote]
I don’t see anything on that link. I would be interested in what Coleman says, i did a fair amount of searching and I have never gotten a straight forward answer. I found one site that discussed HDPE and it basically said in a round about manner that it may leach. I have seen in various places that said that the leaching is likely not harmful to adults. It is probably safe, i just feel that the less chemicals that you expose yourself to, the better.

[quote=“mppatriots”]I don’t see anything on that link.[/quote]It states that the coolers are made from HDPE which is a food grade plastic (same as used in all plastic fermenters) engineered to withstand temps above boiling. For more info on HDPE:

Ok sorry for the u-turn here, but to control the temp better and in an effort to move forward toward automation can someone post a good link for building a RIMS. For now I plan on building and experimenting with just the Tun. I need supply list and point in the right direction as to where to get the parts. I can run 240v but if possible 120v just to avoid electrical work.

[quote=“Shadetree”]And I was curious enough to send an enquiry to Coleman customer service earlier today asking them for temp ranges and composition. I’ll post their reply when I get one.[/quote]OK, so here’s what the Coleman rep had to say:

“All of the materials used in Coleman Coolers and Jugs are approved for food contact. Our coolers are produced from materials that are approved for food contact. That is not the same as saying the cooler is FDA approved. We do not have any certificate from the FDA. We do have a letter from our material supplier that says the raw material is acceptable to be used in food contact applications.”

I was hoping for a bit more info about temperature ranges and an assurance on applications in brewing and BBQing (I also asked about storing paper-wrapped briskets at 190-200F in the cooler for several hours), but at least they confirmed that they’re using food-grade plastic.

Gotta love the vague answers that don’t address high temps. That is why i think that they there is a slight risk.

[quote=“mppatriots”]Gotta love the vague answers that don’t address high temps. That is why i think that they there is a slight risk.[/quote]The vague answers are a result of our litiginous society that will sue a manufacturer for anything and everything. But the coolers are made from HDPE and you can boil water in HDPE with no ill effects (according to the manufacturers of the plastic) and there are much worse things in the brewing world than this, like aluminum kettles ( :wink: ), so without direct information that the mash will leach plastics, I’m going to stick with what works.

I’ve had two keg-tuns in my brewing life. The first one was insulated with the reflective bubble wrap and I used a small coleman single burner underneath to bump the heat. Had some scorching incidents and can testify to the length of the thermometer and screen.

My current tun also uses a converted keg with 3 layers of bubble wrap including the bottom. I used the air duct reflective tape for all seams and my lid is also insulated. the lid is a pizza pan with a handle on top, and I use bungie cords to seal it. No direct fire. In my experience, I have found that if you are meticulous with your strike temp, grain and tun temps, and use a quality software to determine how to get to your rest temp, a sufficiently insulated tun will hold it’s temperature for a very long time, even in winter.

The problem is when you are too low, what do you do? If you are using a pump, drain some wort off and fire up the kettle. Transfer it back and hope you’re not too far over. PITA for sure.

[quote=“moose”]I’ve had two keg-tuns in my brewing life. The first one was insulated with the reflective bubble wrap and I used a small coleman single burner underneath to bump the heat. Had some scorching incidents and can testify to the length of the thermometer and screen.

My current tun also uses a converted keg with 3 layers of bubble wrap including the bottom. I used the air duct reflective tape for all seams and my lid is also insulated. the lid is a pizza pan with a handle on top, and I use bungie cords to seal it. No direct fire. In my experience, I have found that if you are meticulous with your strike temp, grain and tun temps, and use a quality software to determine how to get to your rest temp, a sufficiently insulated tun will hold it’s temperature for a very long time, even in winter.

The problem is when you are too low, what do you do? If you are using a pump, drain some wort off and fire up the kettle. Transfer it back and hope you’re not too far over. PITA for sure.[/quote]
Moose, have you ever considered a RIMS system. It is indirectly fired and you use a heat exchanger and your sparge tank to adjust temps. I have no experience but that is what i was thinking of building.

A keg is all I’ve used. It’s not a PITA, but is hands-on. I stir and recirculate anytime I have the burner on. Insulation would be a great improvement.

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