Do I "need" a 70 qt mash tun?

[jacksonbrown]

My current tun is a 48 qt cooler that doesn't hold temp that well. It'll usually drop 3-4 deg over the hour. I'm considering an upgrade to a Coleman Extreme cooler (we use one for camping and it holds ice for days). There's a 70 and 50 qt available on line for $40 each. I mostly brew 5 gal batches, but also do some 10 gallons. The 48 typically just barely fits the 10's. Any reason not to consider the 70? Do I need to be concerned about head space on the "smaller" batches?

 

[wilserbrewer]

My current tun is a 48 qt cooler that doesn't hold temp that well.

Sorry, I feel compelled to ask. Are you preheating the hell out of it? Are you waiting long enough for the temp of the mash to stabilize prior to taking a temperature. At least 5 minutes? If you don't wait for the mash temp to stabilize, IMO you will read a "false high" temp and think your tun is at fault.

Igloo cube I imagine?

 

[shortyjacobs]

I have a 60 qt and have no problems doing a 5 gal batch in it.

 

[PVH]

What convinced me to go for the 70qt MLT is that I always want 10 gallons of the higher gravity brews. These are typically going to age for awhile. Making 10 gallons allows for more tastings as the beer ages. I don't want to open my last RIS at one year and find out that it's the best one of the batch.

 

[InLimbo]

I use a 70 qt rectangular coleman cooler, and the thing is amazing. Not a single degree drop over an hour. Don't even have to pre-heat it or anything.

 

[wilserbrewer]

While the 70qt should / may work fine...on a five gallon batch w/ 10 lbs of grain mashed at 1.25 qt/lb is just shy of 12 quarts...12/70 is around 17%, or less than 1/5 of the tun will be filled w/ mash, seems a little excessive to me?

 

[jacksonbrown]

Sorry, I feel compelled to ask. Are you preheating the hell out of it? Are you waiting long enough for the temp of the mash to stabilize prior to taking a temperature. At least 5 minutes? If you don't wait for the mash temp to stabilize, IMO you will read a "false high" temp and think your tun is at fault.

Igloo cube I imagine?

No, a Rubbermaid.
I heat my dough-in water up to around 175 and add it to the tun. It tends to stabilize after 10 or so min to my actual dough-in temps, 162 give or take a few deg. Then I dough in, let it settle for 10 min and read. The other annoying aspect of this cooler (and maybe it's other coolers, too) is that I get vastly different reads in different areas. One corner will read 149, another 154, the center is 152. And so on. I just take the averages now and call it good. But like I said, those numbers drop significantly throughout the hour. I would just like a mash tun that's stable.

 

[Moonpile]

Brewed for a long time with a Coleman Extreme 70qt and really liked it. My friends still use it. Almost all 10 gallon batches.

Compared to the keggle MLT with false bottom I'm using now, I really like that it drained out the side and you could get just about every last drop of runnings out of it.

We would overestimate the water temperature by about 5 to 10 degrees, depending on ambient temperatures. Close it up for 10 minutes and then stir until it went down to the appropriate temperature to mash in. Once it was well preheated and the mash was going it showed even temperatures, within a degree, no matter where you measured.

We once mashed 40lbs in it overnight. Went from 148F to 138F in 8 hours. It was Labor Day in MD, so relatively hot ambient temps helped. It seemed to have extracted a lot of tannins, and I wouldn't do that again, but it goes to show . . .

I felt like this mash tun was too big for our lowest gravity beers (1.038 or so), even at 10 gallons as it would loose temp faster with smaller grainbills. In retrospect, I suppose I'd preheat it with twice as much water as I was going to use, and drain some before mashing in. Maybe that would help.

 

[danorocks17]

i just ordered the same cooler you are looking at and I plan on doing 5 gal batch sparg. we will be in the same boat lol

 

[InLimbo]

While the 70qt should / may work fine...on a five gallon batch w/ 10 lbs of grain mashed at 1.25 qt/lb is just shy of 12 quarts...12/70 is around 17%, or less than 1/5 of the tun will be filled w/ mash, seems a little excessive to me?

My latest 5g attempt was an IPA with a 14lb grain bill mashed at 1.33 qts/lb. We had 20qts of water in there. Most of my recipes have a minimum of 11lbs of grain. What's the harm in "too much" space? That kinda sounds like having a garage that's "too big" : )~

 

[emjay]

While the 70qt should / may work fine...on a five gallon batch w/ 10 lbs of grain mashed at 1.25 qt/lb is just shy of 12 quarts...12/70 is around 17%, or less than 1/5 of the tun will be filled w/ mash, seems a little excessive to me?

Not sure how you're doing your math, but less than 12 quarts is wrong. It'd be 12.5 quarts just in water, plus the additional space taken up by the grain, which for obvious reasons is not simply additive, but definitely increases the volume. Promash puts the additional grain displacement at about 1/3rd quart per pound, so 10lbs would be about 16 quarts total.

Not a huge difference though. I only have a 50q cooler (Coleman Xtreme Ultimate), but I don't plan on doing 10gal batches any time soon. The OP does though, and I think it's much more important to have enough space than it is to make sure you don't have too much.

Two main concerns with having too large a cooler:

First is that the water might not be high enough above the grain bed and will cause channeling. This is ONLY an issue with fly sparging though, but I don't think the OP said whether they batch sparge or not.

Second issue is having too much empty space and seeing temperature drops of a few degrees as a result. It's usually not that dramatic, but still... it's not unreasonable to want very stable temps. Luckily, there are a few ways of dealing with this, if you decide it's too big an issue. Some people put blocks of foam underneath their lid to minimize the empty space, while others literally just place (safe) things in the coolers to take up additional space. Bottom line is that there are always things you can do to, in effect, make your cooler "smaller", but you can never make it bigger.

 

[wilserbrewer]

Ah yes....thanks for correcting, 10 lbs of grain at 1.25 qt/lb mashes into less than 16 qts., or less than 25% of a 70 qt cooler.

 

[TheBrewinator]

I converted a 70 quart colemann xtreme, and do a pretty even split between 5 and 10 gallon batches. My last batch was a 4.2% wheat ale (8 lbs of grain) and I only lost 2 degrees over the 75 min mash. I'd say go for it, that way if you do want to do 10 gallon batches or really big beers, you don't have to worry about space being an issue.

 

[jacksonbrown]

Thanks for all the input. I'm a batch sparger, btw.

 

[Jubilee]

I just ordered the 70 qt cooler from Amazon.

Is there any concern (5 gal batches) with too-large of a mash tun resulting in a not deep enough grainbed?

 

[brandonhagen1]

not if you batch sparge

 

[vnakkar]

I've used the exact same 70qt for a year now. I used to wonder if it was just too big for me, as I did a lot of 5gal batches. Then two weeks ago I did a 10 gallon, 1.070 OG beer, and went with a 1.5 qt/lb ratio and filled it! I was happy I went with the larger one that day.

It holds temps just fine for smaller batches with a good pre-heat. Having a looser grist will give you more mass as well, improving heat kinetics.

 

[Jubilee]

Thanks guys, I was hoping to keep the big cooler!

 

[jacksonbrown]

Came in the mail today! Looking forward to converting it.

 

[Paul_Aris]

Love mine, I have done all 10 gallon batches in mine.

 

[jacksonbrown]

Paul, what size tubing are you using? The one I have from my previous tub doesn't fit proper and it looks like your brain and drain set up are very similar to mine.

 

[lumpher]

i have 3 mash tuns: a 40 qt rectangular for smaller batches, a 58 qt rectangular for larger batches, and a 15.5g keggle with false bottom for step-mashing. i realize this is not possible either space-wise or financially for many people, but if you can, it works outstanding. just like you did, i would have gone for the 70 also

 

[Paul_Aris]

Paul, what size tubing are you using? The one I have from my previous tub doesn't fit proper and it looks like your brain and drain set up are very similar to mine.

What ever size the braiding is on a sink or dishwasher water supply line. I bought at home depot and made sure it was truely a stainless braiding not the cheap plastic braiding that looks like stainless. I think I just bought the longer sink supply line they had and installed to the barb inside the cooler and folded the end several times and crimped in a vise or with pliers.

I usually get mid 70's for effeciency. Most recepies I see online or on Northern Brewer, I over shoot a little on my OG so it does a good job.

 

[jacksonbrown]

I was asking about the couplings and the washers. When I took all the metal out of my old tun and tried to connect it to this one I was left with a lot of gaps since the spout on this coleman is larger than the old one. I'm trying to figure out how to keep it leak proof.

 

[danorocks17]

got my 70qt xteme in the mail the other day. the 3/4" stainless steel washers are JUST small enough inside to not fit on the nipple so it looks like I have some dremmeling to do. I ended up getting the 2" nipple instead of the 1 1/2" nipple. did anyone else do this?

 

[Paul_Aris]

I was asking about the couplings and the washers. When I took all the metal out of my old tun and tried to connect it to this one I was left with a lot of gaps since the spout on this coleman is larger than the old one. I'm trying to figure out how to keep it leak proof.

Its been a while since I built it but the best I can remember is I have a close 1/2" nipple between 1-1.5" long with a stainless washer on the inside and outside of the cooler, Tightened the ball valve on one side and the brass female NPT barb on the other. I will have to check but there might be a rubber washer behind the stainless washer on the inside.

 

[jacksonbrown]

So the washers are essentially what's keeping it liquid tight?

 

[Paul_Aris]

So the washers are essentially what's keeping it liquid tight?

Yes, much like weldless fitting. Should be a o ring or rubber washer sandwiched in there.

 

[emjay]

Yeah, if you only have metal washers and don't have a silicone or rubber o-ring pressed up against the cooler, it WILL leak.

 

[danorocks17]

This is how mine turned out from outside to inside on the nipple: *Ball Valve, Male and Female Barb were all 1/2" and the nipple I used was 1/2" X 2". Washers were 3/4" washers*


Male Barb=>Ball Valve=>Zinc Washer=>Zinc Washer=>Zinc Washer =>Cooler wall=>Rubber o-ring that came with cooler =>SS Washer=>SS Washer=> SS Washer=> SS Washer=> Female Barb=> Supply line

Instead of just crimping the end of my supply line I also got a 1/4" brass hex plug. It was an extra $2 or so but it gives the end of the line a good weight so it won't float. I also noticed that the drain hole is recessed, which means the extra length on the 2" nipple (as opposed to the 1 1/2" nipple) was absolutely necessary, other wise my ball valve handle would not completely turn to the closed position.

One other thing i noticed: I read online that a lot of people were having trouble removing the hose from inside the supply line. Once I cut both ends off of it with a rotary tool, all i did was bend open both ends of the line, then holding both ends I simply pushed one fist towards the other while keeping your other fist stationary. this allowed the tube to move out the other end easily while not allowing the metal braid to tighten up. It literally took me 3 seconds to remove the tube. Hopefully this explanation makes sense hahaha.

 

[cpesko]

This Cooler is Great 3 all grain 5 gallon batches do not lose a degree over a hour mash.