Stainless steel mash tun help

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billk911

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I just purchased a brewing system from a guy who sadly passed away. I have 2 large (15 gallon ) stainless pots and one pot around 8 gallons furnished with a false bottom to be used as my mash tun. Will putting a couple of rounds of reflective insulation around the outside be good enough to hold heat? I think not but I would like someone elses opinion. What else could I do to maintain the mash temp besides putting a flame to it? I was thinking of making an insulated box to go around the mash tun. Opinions?
 
Do you know what a decoction is? You remove a bit of the wort and heat it and then return it to the mash to raise it's temperature. It's usually used to do a multi-step mash but there isn't any reason it couldn't be used to maintain the mash temp. A sleeping bag or winter coat wrapped around the kettle will help a great deal. Make sure you cover the lid too.
 
Depending on the temperature where you'll be brewing, you might need more insulation than just reflective... Reflective will help keep it warm, don't get me wrong, but you might need more during the colder months...

If you have a heavy blanket you can use to wrap it up during the cooler/colder months, then I would test with that. You could always wrap it in insulation, fill it up with as much water as you can (get to the fill level you expect to need) get it up to mash temp (what you typically use) and see how long it holds it. Adjust things as you need to, for what's insulating it, to make sure you can hold your temp range for the desired amount of time. If you can hold the temp range for at least 45-60 minutes, I'd say you'll be good. If you need to apply heat after just 15-20 minutes, then increase what you have helping insulate it.

I see it as being better to insulate the mash/sparge vessels a bit more than less. It's easier to let a little heat out than to try and fire more in (with direct heat, or with flame)... I've not brewed with anyone using an electric system, so that could be different. Although I would imagine you wouldn't want to power up those elements while you're mashing since you could scorch/burn grain that's in contact with them (or too close)... Again, I've not used an electric system, so my thoughts on how it works could be off there.

I'm thinking about eventually building a brew setup that would use a double jacketed mash tun/kettle... Something where water of the right temperature would be between the mash tun walls, and the outside air... I would imagine that would help keep the mash tun at the desired temperature longer. Of course, it's probably overkill for a home brewer, but you can always think of something (even if you never make it)... It would probably need to be built by a machine shop, so that everything is welded up properly (especially if I go with stainless inside)...
 
The stainless MLT is meant to be used with direct heat for holding and raising the mash temperature. If you're using gas, that insulation will melt. Even if you're using an electric burner you have to be careful with the type of insulation you use. If you have no intention of direct heating, get a cooler.
 
The stainless MLT is meant to be used with direct heat for holding and raising the mash temperature. If you're using gas, that insulation will melt. Even if you're using an electric burner you have to be careful with the type of insulation you use. If you have no intention of direct heating, get a cooler.

That's odd since I have my kettle wrapped in reflective insulation (from Lowe's, adhesive backed) that has no melting issues at all. I did leave about 1" from the bottom of the pot, before starting the insulation though. I've used it on my kitchen stove to boil in without any melting of the insulation. With a propane burner, you might want a little more space before you wrap it, like perhaps above the ball valve...

My pots are aluminum (4mm thick) so I would imagine they're transferring more heat to the insulation than SS would... Although the 4mm of thickness could balance that out.

You CAN get very high heat tolerant insulation if you want to be sure it won't melt. Basically, it's used more in the automotive arena than in home brewing. But, as with so many things, it can be adapted to fit our needs. Things that are used to insulate header pipes would have more than enough tolerance for use. You'll need to figure out how to get it to stay on the pot (perhaps high heat tolerant glue would work)... Of course, TEST with the insulation before you start brewing with it. Do so outside (especially if using a propane burner) so that you have less to worry about. Best in a well ventilated place too (especially the first time you fire with the insulation on it)...
 
My whole point here is I do not want to have to put more heat to it. I know that I could put heat to it if I want to ( which I may have to do ) but I would rather not. I like the idea of wrapping the pot with a sleeping bag. If I would have to put heat to it that would probably require me to buy another propane heater.
 
9367kp1s.gif

Flexible Foil-Faced Bubble-Wrap Insulation




  • Temperature Range: -60° to +180° F
  • Heat Flow Rate (K-factor): 0.24 Btu/hr. x in./sq. ft. @ 75° F
  • Density: Not rated
  • Color: Silver


That's odd since I have my kettle wrapped in reflective insulation . . . I've used it on my kitchen stove to boil in without any melting of the insulation.
If your comfortable breathing the fumes from overheated plastic. Good for you.
 
9367kp1s.gif

Flexible Foil-Faced Bubble-Wrap Insulation


  • Temperature Range: -60° to +180° F
  • Heat Flow Rate (K-factor): 0.24 Btu/hr. x in./sq. ft. @ 75° F
  • Density: Not rated
  • Color: Silver

If your comfortable breathing the fumes from overheated plastic. Good for you.

NOT, really, what I'm using... Besides, with the 180F upper end listing (what's the point where it actually STARTS to break down? Bet it's a good deal above 180F) it would be fine for wrapping a metal mash tun... Since chances are you won't be going over 180F in that even during a sparge... Use it OUTSIDE, and those fumes are a lot less to worry about.

First time I put heat to my kettle with the wrapping, I did have windows open.. I always have a vent going too (part of the issue with brewing in an apartment)... Air exchange rate: HIGH...

There ARE insulation wraps, many listed on amazon's site, that won't have any issue with high temperatures. Consider how HOT header pipes get... This stuff is made to keep the heat within those. Plus, you can get other insulation made to go between the engine and firewall, keeping heat OUT of the cab... Also high temp tolerant above the range of our needs. Consider how HOT race engines get... 'nuf said...

You can find the right product to do the job, it just takes a little looking, to find it...

Whatever you end up using, just test it before you use it the first time... I would also get a thermometer that has a probe that goes into the MLT/kettle, with a display outside, so that you can monitor temps WITHOUT having to open it up, or pull the insulation off of it... Especially during the cooler/colder months...
 
I do have it set up with a thermometer outside ot the mash tun. I have seen guys use heat with the bubble wrap on but they have left the bottom couple inches open. I think the wrap + maybe something else wrapped around the outside would be fine. Also, in the colder times you can always bring the mash tun inside the house where it is a lot warmer ( I live in northern wisconsin ). I have always used the cooler as a mash tun but I could not pass up the deal I got. All 3 stainless pots with stainless ball valves, false bottom, temp gauges, and other bells and whistles. All this for $200. Needless to say I took the deal and changed my setup. Eventually I am going to set this system up with water pumps. I thank everyone for the input and welcome any more discussion on this. You all have been very helpfull.
 
I mash in thin walled stainless and have never lost more than four degrees - that being in a 90 minute mash. It's ghetto as hell, but I put the tun on a folded blanket, then put a pillow on the lid, wrap another blanket around the whole thing, and drape a winter coat over the top.
 
I am in the process right now of heating some test water. I have the mash tun all wrapped up and ready to do a trial run with some water. I will let you know how it goes.
 
Well, first run I lost 5 minutes over an hour. I noticed a few things that I could have done better. I am going to do another run here with just the insulation on the outside and then do another with a sleeping bag around the mash tun...
 
Rigid foam insulation (foil faced 2" thick)
Duct tape
Cheap hand saw
Hexagonal box (30 degree angle bevels on the edges)
Don't forget the lid
Duct tape hinge, velcro closure
 
I guess that is what happens when you chase around 3 kids and do home brewing experiments at the same time. I guess I should say I lost 5 degrees over 60 minutes. I now have the insulation completely surrounding the mash tun with duct tape over any cracks. I also have a blanket completely wrapped around it to. We will see how this worked in 31 minutes ( or degrees ).
 
Well, I guess you can call it a minor victory. With the mash tun completely surrounded in reflective insulation and every crack covered with duct tape and also a blanket wrapped around the whole thing I only lost 1 or 2 degrees over an hour long period. I would say that is pretty good and probably going to be how I do it from now on.
 
Hey guys,

Sorry to revive an old thread, but I have a question on this same topic.

I recently bought a beautiful 15 gallon stainless steel pot, with thermometer and ball valve. I've also ordered up the ingredients to do the partial-mash IPA recipe from Charles Papazian's "Complete Joy of Homebrewing" ("Laughing Heart India Pale Ale").

The recipe calls for mashing in with 5 qts. of water at 135 F for 30 minutes, then adding 2.5 more qts. and mashing at 155 F for another 45 minutes.

My main concern is that such a small volume of water (5 - 7.5 qts. in a pot that can hold 60) will have such negligible thermal mass that I'll be losing heat like crazy, and will not be able to hold that temperature for even 30 minutes.

Is it safe to periodically add a little heat and stir, to bring the temperature back up to the required level? What would YOU do in my situation?
 
kombat, I would toss out those directions completely for how to mash. I would do my normal, single infusion mash schedule, at the temperature I wanted to get the FG close to where I wanted it to be (typically 150-154F) for the normal 60-90 minutes.

IMO, Papazian's book is seriously out-dated and recipes/directions can be pretty much ignored since they are using such out-dated methods.

Do yourself a favor and use brewing software to figure it all out. You can download/install a trial version of BeerSmith (if you don't already have it) and use that to figure out the mash water amounts (by mash method).
 
image-2383751731-74be16979710d4c4e7c6647856088456.png

Here's my direct fire, gravity powered, jiffy-pop mash tun. It has one layer of 1" aluminum silica (flexible ceramic insulation) wrapped with five layers of heavy duty aluminum foil to keep it in place.
I heat my strike water directly with full power on the burner, no problem!
I got the ceramic insulation from mcmastercarr for $60 + shipping, for a roll large enough to do three kettles.
I'll bet rockwool or even bare fiberglass insulation would handle the heat too.
The mash tun has no hole in it, and is empty of manifold during the mash.
I insert my Lautering Manifold when I am ready to lauter/sparge.
See this for details:
https://www.homebrewtalk.com/f11/hexs-lautering-cane-245608/
I get zero scorching with stirring the mash during temperature ramps.
I loose about 2-4*f over the course of an hour, so I occasionally fire it up and stir to give it a little more heat.
My efficiency is between 80-88% depending what style step mash I use.
I attribute high efficiency to stirring.:mug:
 
Do yourself a favor and use brewing software to figure it all out. You can download/install a trial version of BeerSmith (if you don't already have it) and use that to figure out the mash water amounts (by mash method).

Thanks for the advice - as it happens, I just downloaded and installed BeerSmith last night (the 21-day trial), and I just started reading the Kindle version of Dr. Smith's "Home Brewing with BeerSmith." My concern is that I've already ordered the ingredients and they're on their way as I type, so I'm anxious to get started as soon as they arrive (since the grains will be pre-milled).

So, you'd just do a single step infusion with the whole 7.5 quarts at 155 F right from the start? That's still a pretty small proportion of my kettle - how many degrees should I expect to lose over the 90-minute mash? Should I abandon the 15 gallon kettle altogether and just do a brew-in-a-bag in my 7.5 gallon turkey fryer pot instead? I'd need to find an appropriate bag (everyone seems to be sold out of the 24" x 24" for some reason). Or maybe just wrap my kettle in a sleeping bag and expect to have to add heat a couple of times?
 
Thanks for the advice - as it happens, I just downloaded and installed BeerSmith last night (the 21-day trial), and I just started reading the Kindle version of Dr. Smith's "Home Brewing with BeerSmith." My concern is that I've already ordered the ingredients and they're on their way as I type, so I'm anxious to get started as soon as they arrive (since the grains will be pre-milled).

So, you'd just do a single step infusion with the whole 7.5 quarts at 155 F right from the start? That's still a pretty small proportion of my kettle - how many degrees should I expect to lose over the 90-minute mash? Should I abandon the 15 gallon kettle altogether and just do a brew-in-a-bag in my 7.5 gallon turkey fryer pot instead? I'd need to find an appropriate bag (everyone seems to be sold out of the 24" x 24" for some reason). Or maybe just wrap my kettle in a sleeping bag and expect to have to add heat a couple of times?

I use 1.25-1.5qt water per pound of grain in my mash. You need to do what feels right for your hardware/recipe. There are plenty of methods posted for keeping the temperature stable in your mash tun. Pick the one that works best for you. Personally, I've wrapped my mash tun in a high temp welders blanket. Works great during the warmer months. I'll be making a reflectix sheath to use during the cooler/cold months too.
 
What would YOU do in my situation?

I would mash the grains in a grain bag in a smaller stock pot and not muck up the kettle w/ the grains. Assuming it is only 5 lbs or so you can mash them in a kitchen stock pot. Get the mash in the low 150's and put it in a warm oven for an hour, rinse grains and add runnings into your boil kettle and proceed.

If you carefully monitor the temperature, you could likely do it in your large kettle as well.
 
OK, I ended up biting the bullet and just building a cooler mash tun. :) I went to WalMart tonight and bought a 48 qt. rectangular cooler, and went to Home Depot and bought the fittings for the tap. My 15 gallon boil kettle has a bazooka screen in it, and it will fit the fittings in my new mash tun, so I think I should be able to do a simple batch sparge with my new setup (up to 12 gallons).

Thanks for the input guys!
 
so its cold up here in tahoe..was thinking about using a sterno under my mash tun to maintain my temp. any thoughts on that approach.
 
elsphinc said:
so its cold up here in tahoe..was thinking about using a sterno under my mash tun to maintain my temp. any thoughts on that approach.

The trick is that even a sterno gets pretty hot and could cause scorching of the grain without stirring, and stirring causes a lot of heat loss! A sterno flame likely prohibits insulation, which is essential.

My .02 is that you will be far better served trying to insulate with blankets or old coats then applying heat with sterno.
 
so its cold up here in tahoe..was thinking about using a sterno under my mash tun to maintain my temp. any thoughts on that approach.

I seriously doubt that will do much of anything to a keggle full of mash. You'd be far better off with a propane burner under it. I did that while brewing with a friend, on his porch, in the winter. With an insulating wrap around the keggle (welding blanket) I didn't need to do much to maintain mash temps. IMO, you'd be better off getting some insulation on the mash tun before you try to use sterno. Also keep in mind that when you're adding heat post mash-in, you need to account for thermal drift. The temperature will continue to rise even once you've turned off the heat. I would assume a 2-5F increase once you kill the fire under it. You'll also need to stir the mash while heating to avoid scorching the grain. It will also help to equalize the temperature inside.
 
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