Another pot size question

[steveT]

I'm just designing my first AG brewery, and it's going to based around Nordic pots. I know this gets asked a lot, but I'm wondering about sizes - specifically the size of the mash tun. I've spent the last hour or so searching these forums, and I think I'm even more confused than when I started! :lol:

I anticipate that I will be making 5gallon and 10gallon batches. While it would be nice to have the option of making larger sizes, it's not very likely, at least not in the short term. What pot sizes should I be looking at? I've been looking at 50L/38.5L/50L, 70L/50L/70L and 100L/80L/100L combination's.

I've never brewed all grain before and so I'm still unsure about the volumes involved including grain, how much I will lose to evaporation during the boil, how much is needed for sparge etc.

Part of me is tempted just to get the largest sizes - doubling the size of the stock pots from 50L to 100L for HLT and copper makes only a small difference to the cost, and if they are not full then that makes no difference either, and I always have the option to brew bigger in the future.

It's the mash tun that worries me - what if I'm only doing a 5gallon batch in an 80L mash tun - may that be too big? Is a 38.5L mash tun too small for 10gallon batches?

What size HLT, Mash and coppers are you guys using, and for what final volumes?

 

[Muddydisco]

You can still mash a small brew in a 80ltr thermobox, because the surface area isn't that much bigger than the 50ltr it's just taller.
When I worked out the surface area of my 44ltr coleman coolbox, I think it was 8cm2 smaller than the 80ltr Thermobox.
Your choices of combinations are good The 50ltr pots won't be any good for 10 gal so I would discard them, 70ltr safe enough for 10 gal but no more, 100ltr good for more. It's your choice :thumb:

 

[steveT]

Cheers muddy...that's exactly what I wanted to know :thumb:

 

[prolix]

I have 70l 38.5l 70l all thermobox it is great, but if I started from scratch I would get a bigger mash tun and bottom tap it, 50l would do it for me. big enough for a strong 10gallon brew and easy for a 4% brew my main stay.

 

[ano]

If you were worried about the dead air above a mash in a mash tun, don't be, it doesn't have a great thermal capacity so won't change the ability of the mash to hold a temperature, just be sure to fully pre-heat the tun, as you'll be adding less liquor to strike with.

The only worry might be an increase to the deadspace in the bottom of the tun, i.e. you may lose a little more wort in a bigger mash tun with than a smaller one, but if, as muddy says, the diameter is similar it won't be a bother and can be accounted for.

 

[BarnsleyBrewer]

For 10 gallon I'd go with..........
50L HLT
50L Thermo
70L copper.

BB

 

[Vossy1]

I used to brew 10 gals as standard, using a 50ltr MT, and 70ltr boiler & HLT.
For 'heavily' hopped beers (read IPA's) you would be better off with a 100ltr boiler though.

 

[steveT]

I used to brew 10 gals as standard, using a 50ltr MT, and 70ltr boiler & HLT.
For 'heavily' hopped beers (read IPA's) you would be better off with a 100ltr boiler though.

dammit!.....I was all set for a 70/50/70 combo until I read this. IPA's are my favourite. Why does the heavy hopping of IPA's effect the boiler size needed? I'm new to AG....

Hmmm.....maybe a 100/80/100 is better anyway......this is for life, not just for christmas :hmm:

 

[Vossy1]

dammit!.....I was all set for a 70/50/70 combo until I read this. IPA's are my favourite. Why does the heavy hopping of IPA's effect the boiler size needed? I'm new to AG....

That depends on the sort of IPA you make. If modern IPA, read 40 to 60 IBU, then you'll be alright, if making old fashioned IPA's, barley wines, RIS in volume, then you'll need more room as the hops absorb a lot more.

Hmmm.....maybe a 100/80/100 is better anyway......this is for life, not just for christmas

That's my way, though I have just made a 50ltr boiler for smaller batches. At the end of the day there's very little difference in the thermo box mash tuns due to the small circumference increase v volume, as already mentioned. HLT size is of no importance, the only real concern is boiler size if making smaller batches.

 

[steveT]

the only real concern is boiler size if making smaller batches.

Why is the boiler size a concern with smaller batches? I plan to use a counterflow chiller for cooling the wort as it drains to the FV, so there are no issues with wort depth....

Edit:...is it a depth at finish thing? ie the electric elements being exposed with only 5gallon final volume as a target for the smallest batches?

 

[Vossy1]

Why is the boiler size a concern with smaller batches?

It's more to do with the thermal loading on the wort due to heat input and volume to surface area :thumb:

is it a depth at finish thing? ie the electric elements being exposed with only 23L final volume as a target?

That can also be a problem.
The main issue I had was forming a decent hop bed to filter out the cold break. Naturally this isn't a concern if dropping the cold break post cooling :thumb:

 

[steveT]

Ok thanks, nice to have good advice from experienced folk.. :thumb:

..plenty of food for thought tonight!

 

[ano]

This was an idea I seem to remember floating a while ago but can't seem to find it now...

There's a calculator here: http://www.rackers.org/calcs.shtml

which from my reading of the source appears to add 0.67 to the water:grain ratio (in litres:kilos) and multiply that by the weight of your grain, the result being the volume required for the mash. My reasoning being that they assume if you have 1:1 then for every litre of water there's a kilo of grain and together those will take up a volume of 1.67 litres and that the absorption is pretty constant, the 0.67 looking like a rounding of 2/3. I think this may be more accurate around the standard bounds of brewing, i.e. a ratio of 0 or infinity yields ridiculous results.

I wanted the mash volume in terms of degrees gravity and brew length to tell how much of a certain strength beer I could brew.

So

degrees gravity (in brewer degrees i.e. 1.075 = 75 brewer degrees) = (weight of grain [kg] x potential degrees extract x efficiency (%)) / brew length [litres]

Or

weight of grain = (degrees gravity x brew length) / (potential degrees extract x efficiency)

and from http://www.rackers.org/calcs.shtml:

volume of mash = weight x (0.67 + water to grain ratio)

Substituting weight from Wheeler into Rackers:

volume of mash = [(degrees gravity x brew length) / (potential degrees extract x efficiency)] x (0.67 + water to grain ratio)

So where does this get us?

Well, if you know your brewhouse efficiency you can take a weighted average for "potential degrees extract" based upon your recipe, or maximise different variables to see how much 1040 wort you can make with your tun or how strong can I make 10 litres of wort in your tun. I actually started looking at python, ruby, c#, java and all the other languages I've ever typed hello world in to see if I knew how to create a nifty slider based graph thingy to plot it all but it turns out I didn't.

Of potential interest, is if your brew length is 23 litres, the potential extract is 300 and the water:grain ratio is 2 then:

volume of mash = [(degrees gravity x 23) / (300 x efficiency)] x 2.67

which is pretty much 0.2 x (degrees gravity)/ efficiency

So if your brew length is 23 litres and you use a mash ratio of 2 you simply divide your desired OG by your efficiency and divide that by 5 to get how bug your mash tun needs to be.

i.e.

if your efficiency is 60% brew length is 23 litres and you use a mash ratio of 2 then the volume of the mash ought to be OG/3.

if your efficiency is 80% brew length is 23 litres and you use a mash ratio of 2 then the volume of the mash ought to be OG/4.

I may have been drinking and all that may be wrong (or at least the fundament was flawed). Having done all that I've never actually been bothered to test it lol.

I've seen better men than me run their harebrained ideas up the flag pole only to have them shot down by people who actually know what they're talking about so yeah, have at it.

 

[pjbiker]

Hi Steve,

Look at the thread in my signature you'll see the 70L, 38.5L 70L 'Nordic/ebay France' set-up I use to brew 10gal batches. I've just installed the 38.5L tun. I nearly went for the 80L but it cost a bit more and my space was a bit limited (see my photos). 38.5L is fine. The first brew I just did yielded 45L (actually collected in the fermenters) of 1.055 OG wort using 10.3Kg of grain with a 2.5:1 ratio of liquor:grain. That was at 81% overall efficiency (which is the best I've had). FG was 1.012 making the brew 5.6%ABV. I reckon there was a good 4 inches of space above the mash so could have got more, maybe 2Kg of grain with liquour in, maintaining the same liquor ratio.
Assuming the same efficiency that would give you about 10gallons of about 6.8%ABV as an estimate. That enough for ya? :drunk:
Don't try and boil more that 65L in a 70L pot as it tends to escape but it's fine for 10gal batches.

 

[mashman]

Just to throw my hat in the ring, I only want to go to 25litre brewlengths so I've gone for 50 / 50 / 50

 

[steveT]

It's been a while - but after a bit of overtime came my way this month, I've ordered my shiny pots today :party:

I went for 2 x 100L stockpots and a 70L thermos in the end, the philosophy being that I'd rather spend the few extra quid and only half fill them than end up wishing I had got bigger ones. They'll apparently be here in 3-6 days, by which time I'll have decided what I'm going to do about elements etc.....there are so many different options.

Photos (and I'm sure many more questions!) will follow once they have arrived :mrgreen:

 

[simonranson]

Nice one Steve :)

Have fun with the build!

 

[steve963]

It's been a while - but after a bit of overtime came my way this month, I've ordered my shiny pots today :party:

I went for 2 x 100L stockpots and a 70L thermos in the end, the philosophy being that I'd rather spend the few extra quid and only half fill them than end up wishing I had got bigger ones. They'll apparently be here in 3-6 days, by which time I'll have decided what I'm going to do about elements etc.....there are so many different options.

Photos (and I'm sure many more questions!) will follow once they have arrived :mrgreen:

thats what ive just got, just fitted 2 kettle elements to my hlt/copper and a bottom drain to the mash tun, using tank connector and elbow etc made false bottom out of £2.50 stainless cake cover mesh (not sure how it will work!), hoping to get 15 gall brews once i get good. good luck with the install

 

[Vossy1]

It's been a while - but after a bit of overtime came my way this month, I've ordered my shiny pots today

:party: