Filling Headspace - Mash Tun

I built a mash tun out of a 52 quart rectangular cooler. For many, many batches I was getting HORRIBLE temperature control and it was really hurting my efficiency. I have a lot of headspace when I do average gravity beers and I lose a lot of heat because of it.
What are some options or methods you have used to control temperatures with coolers that have a lot of headspace? Thanks!

Are you preheating your tun before mashing in? If not, put several gallons of the hottest tap water in there while you are heating your strike water. Is your cooler lid insulated? If not, you can drill small holes and fill it with Great Stuff foam. I have a 50 quart square cooler, and I don't worry about the headspace, but by using those two techniques my mash stays within one degree for the whole mash.

probably not worth it for such small scale, but worth a mention... when you have a large open tank of hot water, you can reduce your evaporation rate and heat loss considerably by adding some plastic insulation balls to it. they form a blanket over the top of the liquid.

like:
http://www.eccllc.us/applications_advantages.php

As you can see I haven't checked this in a while.
I've tried preheating the tun the last time I mashed; I heated up my strike water about 20 degrees hotter than what I would normally and added to the cooler. Once the temperature reduced to my target temperature then I added the grain to reach my target mash temperature. I still saw significant loss in temperature, though.
The lid is pretty hollow so I'll try using your foam insulation idea next.

michaeltrego said:

Are you preheating your tun before mashing in? If not, put several gallons of the hottest tap water in there while you are heating your strike water. Is your cooler lid insulated? If not, you can drill small holes and fill it with Great Stuff foam. I have a 50 quart square cooler, and I don't worry about the headspace, but by using those two techniques my mash stays within one degree for the whole mash.

Click to expand...

Cover & wrap with a blanket. And I always bring my tun inside where there's no wind.
I lose maybe a degree or two over an hour.

I have tried the great stuff on 2 separate lids and every time the foam just collapses and I don't get that nice thick foam in there. I am not sure if I am adding to much but I can never get it to work. Any advice on my 3rd attempt? What I have been doing so far is using some insulation board cut to rest on top of the liquid which gives me zero head space. The only problem with this is it has to be wrapped in saran wrap to keep it from directly contacting the mash.

Greatstuff needs air/moisture to activate & expand...if you're pushing into a small, relatively sealed space, it's not much different than staying in the can. Some guys have cut the top off their lid, filled with foam, cut it down, then put the lid back on.

But again, I just use a blanket. Don't overthink it or create more work for yourself, IMO.

ekjohns,

When you rest your pad on top of the mash, did you manage to cut your heat loss? I have a 5 gallon rubbermaid cooler tun and I am losing heat like crazy, 7-8 degrees in an hour. I even double wrapped the outside of the tun using Reflectix from HD but It's not helping much. The lid of the cooler got really hot and I know that they are hollow so it is the only culprit I can think of.

I saw a thread where someone took sheets of Styrofoam and cut to the shape of the tun and covered them with tape or something then just filled the headspace with these. They float on the top of the mash.

For filling the lid of the tun with Great Stuff, you could drill some holes then squirt in a little foam as far out to the ends as possible, let that set, then add more and let it set. Go in small additions until the lid is filled.

I read about drilling and spraying some foam in the lid but am concerned that the foam will not expand and dry leaving behind a gooey mess like many had warned. I did cut and make a foam pad, I cut it to fit the tun snugly that I have to push it down there. Hopefully, it will work.

kh54s10 said:

For filling the lid of the tun with Great Stuff, you could drill some holes then squirt in a little foam as far out to the ends as possible, let that set, then add more and let it set. Go in small additions until the lid is filled.

Click to expand...

I did the same thing and it worked well. Drill lots of holes.

Here is my thoughts:

Great Stuff
1. great stuff can be a pain. the first cooler lid i tried was to just spray a bunch in there and let it expand. Well this turned into a gooey mess.
2. on the next attempt I tried drilling 8 holes on the lid and sprayed little bits in each hole. This appeared to work as I got nice solid foam when looking at the hole. HOWEVER when I tested it by drilling a hole 1" away from the original hole there was nothing but a gooey mess so IT DID NOT work for me.
3. On my 3rd lid (I got a bunch of coolers for like $5 a piece at a garage sale) I sprayed a little foam and then let it sit for a day then checked that area and it was the same as test 2.

Great Stuff conclusion - I am sure some people get it to work but I think there is a very fine line between the right amount and total failure. It seems one you get a little goo your screwed for the rest of the lid. This stuff really needs air flow to expand

Foam inserts
1. Cut 2 circles of 3/4" foam and glued them together. I think sanded them to a perfect tight fit in my cooler. However, because I could not get them water tight I would only push them down enough to get the lid on thus leaving head space. This worked great at keeping heat from leaving the lid. After an hour it would be cool to the touch. I am sure if I would have floated them on the mash it would have been even better.

Foam insert conclusion: easy and efficient but have to be careful about keeping it clean.

I would suggest that if you want a nice clean look to cut the entire top half off the lid off using a knife. Then fill the lid with great stuff let it harden then shave it down so the top of the lid can be glued back on. Use good glue like gorilla or my favorite epoxy. If you don't want to cut the lid I would cut 2 semicircles of foam so each piece can fit into a vacuum sealers bag and seal them up making them water tight. This way you can float them right on the mash. You can also check your temps without having to remove the inserts since they split in the middle and just wash them in the sink when your done.

With all that said I was able to cut my heat loss from 7-8 degrees/hour down to 4-5 degrees/hour. A few batches ago I doughed in and hit my mash temp on the spot after stirring for like 3 min solid 156F. I added my inserts and put the lid on. 15 min later I gave it a quick stir and check the temps and it had dropped 4 degrees to 152F. Added 1 qt of boiling water and got it back up to 156F. Sealed her up and checked 45 min later. Temp was 153F. So as you can see I am still loosing heat although I do not think it is from the lid anymore but just all over. One thing to watch though is that the biggest loss is in the first 15 min. I think this is due to equalization of the temp and grains that just takes time (no amount of stirring will do this). My schedule now is to go 2 degrees over my mash temp and then 20 min later I add 1 qt of boiling water then let it ride for another 40 min. It is time consuming and I am getting temps that are not fully stable but at least I can keep it within a 2 degree window. Another thing that helps is to increase your water/grain ratio. You might see a small decrease in efficiency but better temp stabilization. I am now looking at recirculation with eBIAB.

Great stuff ekjohns. (see what I did there?) I'll have to try the foam insert. A third option is to just cover the whole thing with a thick blanket, I've been surprised at how well that works.

Just to be clear, you were losing 4-5'/hour even with the lid filled with Greatstuff and foam pads placed inside the tun? I have a thermometer and ball valve installed on my cooler so that could also contribute to further heat loss.

I have recently moved to Miami and it seems like the warm weather offers no help. My brother uses a 10 gallon rubbermaid cooler from HD. He lives in Atlanta and when he brewed, 10 or 5 gallon batches and cold or not outside, he lost only like 2 degrees max.

Correct. It sucks I know.

I have been lazy with adding blankets so that might be a problem of loosing some extra degrees. I even preheat my cooler with hotter water for 20 min before I add the grain. A lot of people say they have no problems and loose less than a degree. One thing that I do not think some people pay attention to is zone temperatures. If you take a reading at the top of the mash and at the middle and bottom they will all be different. If I let it sit for 1 hour then take a temp at the top I see about a 2 degree drop. If I stir I see 4 degrees. How is your brother taking a reading?

For 10 gallon batches there is double the thermal mass so it stays hotter longer. Try heating putting 4 oz of boiling water to 1 Styrofoam cup. Then in another add 8 oz of boiling water. Wait 10 min and measure. You will see that the 8 oz is much hotter.

I'm getting the same 6 degree loss in a round cooler. I've preheated, and I tried blankets and heavy ski jackets. No change. I don't want to thin out my mash too much. Wondering if its possible to draw like a qt of liquid from the mash, heat to a certain temp and return it to the mash without any adverse effects.

If you solve this dilemma, definitely update the thread.

He has a thermometer with 4" probe installed so it should be taking the reading right in the middle of the mash where the temperature should be most stable. The mash should be colder around the side of the cooler and I agree with you without stirring it, there is no telling. I made a reflectix jacket for the tun so I will see soon if it will help. I will also use the 15 minute infusion method to keep the temperature stable. I think I read somewhere that most conversions are done within the first 30 minutes.

ekjohns and krovitz,

You both are using 5gal cooler, correct? I just built a custom heat reflective jacket for it. So, I will let you guys know.

I have a 5 gallon (blue) igloo and a 10 gallon (yellow), but most of my measurements were on the 5 gallon.

Krovitz - I would recommend taking out ~1 qt of water before you add the grains. Then when you get to the 15 min mark, boil that water and add it to the mash. Taking some out will not be a problem as that is only a tiny bit. However, if you account for that liquid before you add grain you can get it boiling before you have to open the cooler. This way the addition of the water will be quick and simple

Royale: indeed. 5 gal HD cooler. Let me know how it turns out.

Ekjohns: thanks. I'll give that a try this weekend. I always wondered if the boiling water would act as a mash out and shut off the conversion but I'm still learning how it all works together.

The boiling water may shock the enzymes right by were you are pouring the boiling water but there will be plenty more in the rest of the mash to convert your starch to sugar. With that said the temperature difference for the enzymes are not an all or nothing transition. It is more like at 152F enzyme A is at 80% activity while enzyme B is at 100%. Raise it to 156F and enzyme A drops to 20% while enzyme B is now at 80%. If you let it cool back down to 152F your enzymes will move to A - 50% and B - 90%. As you can see they will not get back up to their starting activity but will still be working. Never the less 1 qt of boiling water is not going to cause any noticeable difference for the whole mash. I would not worry about it.