Need advice on mash tun size. How big is too big?

[dustinstriplin]

Hi, I’m upgrading from my cooler mash tun to a ss brewtech Infussion mash tun. My cooler mash tun holds 10 gallons and it’s frequently not enough for my 10 gallon batches. My average batch has roughly 30 lbs of grain which will take up around 12 gallons at 1.3 quarts per lb mash thickness.

I’m eyeing the 20 gallon tun because My 10 gallon batches would never be limited by my mash tun size again. This would be the last mash tun id ever need. I would be able to mash a 10 gallon batch of barley wine. However, I make super high abv batches infrequently. My concern is that the 20 gallon mash tun would be too big. I’m worried that the grain bed wouldn’t be deep enough for my average 20-30 lb batch. I’m also concerned that too much head space would allow the mash to cool too much in a 20 gallon mash tun. I may even do an occasional 5 gallon batch; this means my minimum batch would require 6 gallons of mash volume. The average is 12, and the max is 20.

I’m seeking advice from anyone who has experience with this kind of a situation. Are my concerns founded or should I just buy the 20 gallon and not look back? Are there any concerns I’m missing? This is a big purchase so I want to consider this purchase carefully. The alternative I’m considering to the 20 gallon tun is the 15. The 10 gallon tun is too small for my average batch.

Thanks, Dustin

 

[RM-MN]

Something different to consider. Buy a bag to line your current cooler. Get your grains milled finer so you can increase your mash efficiency, then reduce the amount of base malt to get the same OG. If it works out, you keep the current mash tun cooler and have invested only the price of the bag (Swiss voille curtain material makes a great bag, may not even need to be sewed for this) and the reduced base malt will pay for the bag in about 3 batches. If it doesn't work out for you, you have only wasted the cost of the bag. You then will have the smaller mash tun for the smaller batches.

 

[Silver_Is_Money]

Something different to consider. Buy a bag to line your current cooler. Get your grains milled finer so you can increase your mash efficiency, then reduce the amount of base malt to get the same OG. If it works out, you keep the current mash tun cooler and have invested only the price of the bag (Swiss voille curtain material makes a great bag, may not even need to be sewed for this) and the reduced base malt will pay for the bag in about 3 batches. If it doesn't work out for you, you have only wasted the cost of the bag. You then will have the smaller mash tun for the smaller batches.

How fine can you go on the crush with a bag liner?

 

[RM-MN]

How fine can you go on the crush with a bag liner?

I don't really know. My Corona mill won't go any tighter.

 

[Silver_Is_Money]

I don't really know. My Corona mill won't go any tighter.

Do you have to lift out the bag for it to drain? I'm hoping to be able to use my cooler and bag combination exactly as I had used the same cooler when it had the braid in it. I don't have plans for lifting out the bag in order for it to flow.

 

[RM-MN]

Do you have to lift out the bag for it to drain? I'm hoping to be able to use my cooler and bag combination exactly as I had used the same cooler when it had the braid in it. I don't have plans for lifting out the bag in order for it to flow.

If there is only the bag it may need to be lifted as it would push up against the outlet an that would restrict the filter area. If it were over a false bottom or manifold it probably would drain on its own. I only do mine in the boil pot so then it does have to be lifted. I have a range hood over my stove so I can barely lift mine high enough to put a bowl and colander under the bag.

 

[dustinstriplin]

Thanks for you input. This is good advice for someone who isn’t sure whether they need a new tun. I usually get between 75% to 80% efficiency in my cooler tun so there’s really not a whole lot further to go with it.

Please keep this thread on topic. If anyone has experience with using a large mash tun for a wide range of grain bills then I’d love to learn from your experience.

 

[Staticsouls]

I can fit 30 lbs of grain in my 15 gallon mash tun.

 

[dustinstriplin]

My first comment literally says that 30 lbs at 1.3 quarts per gallon takes up approximately 12 gallons. Please guys, let’s keep this on topic.

 

[Staticsouls]

Well if you are recirculating your mash, then your temps should be stable enough despite head space.

If you are not recirculating, then yes, you will lose heat from the larger head space.

 

[dustinstriplin]

That’s good to know, I’m glad that recirculating helps. I’m going to recirculate for the last 15 mins. I don’t have a rims tube so I don’t want to recirculate for the entire mash. I’m not against turning the pump on every 15 mins to help stabilize the temp.

 

[Staticsouls]

If you have an immersion chiller you can run your wort from the tun to the pump to the chiller placed in kettle with hot water and back to the tun. This will keep the temps close to the same and should help keep temps stable. You can run the pump for the entire mash this way.

 

[mongoose33]

Can you keep the original mash tun for when you do smaller batches ?

 

[dustinstriplin]

Good idea, I do have a retired immersion chiller. I’m gonna drop the Extra immersion chiller in my HL tank. This helps a lot with my decision, thanks!

 

[augiedoggy]

I use a 16 gallon bayou classic kettle as a mashtun for both 5 and 10gallon brew sizes (I use a rims so no pratical point in an insulated tun plus Ive read about what a POA they are to empty and clean vs just carrying the kettle outside and dumping in my compost bin) its 15.5" wide with a FB and a long section of finer stainless braid attached to the diptub under that as a "last chance filter" to prevent any grain from entering the small dc pumps I use. I do recirculate which makes the headspace a non issue.
I average 91% efficiency for 10 gallon brews and close to that with 5 gallon brew sizes though I dont do many of those these days.
The general rule is the wider and more shallow the grainbed the more efficiencies suffer when sparging but I dont seem to have this issue and I believe its due to the slow speed I both recirculate and fly sparge at preventing the channeling that often occurs with homebrewers using large 7gpm pumps which IMO are too large for this task and most dont throttle back enough.

 

[Mhakala]

SS Brewtech 20 Gal Mash tun has no problem with 42lb of grain and I can get a 1.070 with a 20 gallon batch with a 13 gallon mash in and a spare of around 12 gallons.