• BatchSparge

Batch Sparging

Unfortunately every time I see an esky now I just see a mashtun that hasn't quite reached its potential.

Just because this works for me, you need to figure out if its the right way to go for you.

In A Nutshell

My take on batch sparging is pretty simple, there are three basic water additions and two drains:

1. The mash water.
2. The mash out water followed by drain.
3. The sparge water followed by drain.

The second step is optional - just combine the first two steps into the main rest. Heck even the 3rd step is optional but you will probably use a little more grain to make up for the lower efficiency of "no sparge".

As you can see my German isn't too good.

Anyway, the aim of mashing is to:

1. Convert as much of the starch in the grain into fermentable sugars (give or take a few non-fermentables).
2. Get out as much of the dissolved sugars into the brewpot while leaving all the husks and other cruft behind.

How hard can that be?

Why Batch?

1. It is fast.
2. It is simple.
3. Requires minimal equipment (no sprinkler systems). A fly sparge system does look much more impressive though.
4. Forgiving, far less likely to suffer from the pH rising too high.
5. Some great brewers out there do it. Yes and some crappy ones too.

Some people say batch sparging is not as efficient as fly sparging. They may well be right but (update see poll results for some numbers):

1. Buying a little extra grain won't break the piggy bank.
2. I routinely get 85% efficiency and I if I wind up my mill a bit tighter I can hit over 90%. I prefer speed over efficiency though.

Equipment

I mash in a 48 litre esky (cooler) - my mashtun. I previously used a smaller one but the principle is the same.

This is an earlier approximation to what I had in the mashtun, in reality, it now looks more like:

The only brass part left is the compression nut. I use teflon tape on the thread so that liquid doesn't leak through under the nut.

This is what is inside - some braid of a flexible plumbing hose (brand name "Easy Hooker").

See All grain #2 for more details).

You will also need an accurate, water proof thermometer.

A Few Calcs

Don't sweat on the maths. Remember centuries ago they didn't have calculators. And their eskies were probably pretty primitive too.

Lets assume we have a grain bill that totals 5kg and want 23 litres in the fermenter. Everyone's equipment varies but I need to aim for 35 litres total from mash and sparge to get this, that means even more going into the mashtun. It's not because I am wasteful, the grain soaks up water and also usually there is some left in the bottom of the brewpot. Furthermore, when you are boiling, you might lose 20% of the water as steam. This is perfectly normal. Oh yes and from boiling to serving temps water contracts about 4%.

And just to state some things that may or may not be obvious:

1. The grain has to be malted (or at least most of it).
2. The grain must be crushed.

I crunch all these numbers with Brewsta my open source brewing software. The volumes and temperatures for a real brew (an APA) are:

Notice how the temperature of the water you add (strike temperature) is usually hotter than the target temperature of the mash. This is due to the thermal mass of the container and grist already in the mashtun. On the Brewsta setup page I have entered the thermal mass of the mashtun (actually I have stated this in terms of "equivalent mass of water").

The Process

Mash

If you taste some of the white floury stuff in the grain, it isn't really sweet. It is basically starch. Mashing activates enzymes which convert the starch into sugars that yeast can turn into alcohol. The enzymes act a bit like a tree mulcher - starch is just long chains of sugars. See IodineTest for a time series of images using iodine solution as an indicator of starch (or lack of).

It turns out that I aim for roughly 3 litres of water for every kg of grain during mashing. Don't ask me why, I just read it somewhere. Actually its a bit like making porridge, it just looks right.

So that gives me around 15 litres of mash water to be heated. Which brings us to temperature. This is one parameter you will have to measure and get fairly close. Take notes because differences in equipment mean that your setup won't be quite the same. Lets say we aim for 67°C mash. So you heat up 15 litres of water to 67°C right? Wrong. The grain and esky absorb some of that heat. In fact I had to aim around 7°C higher (strike temperature) than that to hit 67°C in the mashtun. You can download programs like Brewsta, Promash, Beersmith etc which can do the maths for you [see links below]. Or you can just create your own spreadsheet. If you are unsure, remember you are likely to have more cold water on tap than hot so overshooting is easier to control and just start with something like +10°C. Having said that, apparently modern malts can convert fairly quickly so if you are way too hot, your beer might finish a bit fuller bodied than you were expecting (higher mash temps result in more unfermentable sugars).

The great thing about mash temperature is that there are so many to choose from.

If it is your first ever attempt with an esky, you have a problem in trying to estimate how much heat the esky will soak up. For my 45 litre esky, I assume that it soaks up the same heat as 1.2 litres of water, a figure I reached by trial and error.

And thanks for the people that sent me links to online "strike temp calculators": I will add more when I get a chance:

Grain and Grape

The great thing about mash temperatures is that there are so many to choose from. Near the top, down the bottom, at the start, in the middle: all give different readings¹. I make sure mine is all stirred up, wait 5 minutes then push the thermometer well into the grain.

Now since I have in mind an American Pale Ale, I am just going to use one temperature "step". I leave the mashtun alone for an hour or so (some recipes might require more like 90 minutes).

The liquid will be a lot darker in colour and runnier than what it started out. It will also taste sweet. This is good. The great thing is that while the enzymes do all the heavy lifting, you can have a beer.

Mashout

After the mash, I don't drain, I add some more, hotter water (probably boiling) to get the temperature up into the low 70°'sC. How much water? I aim here (somewhat arbitrarily) for the same volume that the grain will soak up. To calculate this, multiply your grain weight by 1.1, so for my 5kg grain bill I will add 5.5 litres, lets just say 6.

I stir that up real good and let it settle for 5 or 10 minutes. I drain 2-4 litres and gently move this back into the mashtun. You want to settle the grain bed down so the wort runs clear, tipping it in from a great height doesn't help.

Then I drain all the wort into the pot as fast as I can. Now I know you hear things like "sparge slow" but that doesn't apply to batch sparging. You can put this on the burner if you like to get it to the boil.

What I have in the brewpot is around 15 litres of beautiful wort. It is no coincidence that this is half the total wort volume (pre boil). There is nothing forcing you to mix the two halves together, you could whack them in two seperate fermenters and have a heavy and a light beer.

Sparge

Now if you taste the grain at this stage, it is still a little sweet - we want all that sugar in our beer - not in the compost heap.

Now I put in another 17 litres of water, at the same temperature as you ended up at the end of mashout (say 72-75°C). You stir this like crazy, remember you are trying to suck out all the sugar that is sitting in the sludge. You are not really worried about conversion anymore, just dissolving as much sugar as you can into the sparge water.

After recirculating 2 or more litres to get a clear runoff, drain as fast as you can again.

And there you have it, 35 litres of liquid gold in your brewpot.

Links and Tips

Really you should be listening to dudes who know lots about brewing, like these guys ...

• Batch Sparging An informative description by Denny Conn.

• Batch Sparging An article by Steve Nicholls with worked example.

In "How To Brew" by John Palmer (ch 12) he suggests a compromise of mash conditions. He uses US units. In SI units these are (and this is a compromise):

• 3 litres/kg of grain
• 65-68°C.
• pH 5.3

Efficiencies

There are three kinds of people in this world, those that can count and those that can't.

If you frequent various beer forums, then you might have seen questions which boil down to "Is my efficiency ok?". Usually the answer is "don't sweat on efficiency" and that is a good answer. However me being the curious type, I wanted to find out a more satisfying answer. Some web based forums have a poll facility, which I thought I would put to good use to try to find "the answer".

Members of brewboard were asked "what is your normal efficiency?" (see topic for details). It is specifically about efficiency into the kettle. Brewers were asked to nominate their method of sparging (fly/batch) and their efficiency.

For the record, I don't think stellar efficiency should be a high priority for brewers, brewing good beer is. To that end consistency is probably more important and grain isn't the most expensive part of the brewing process. Having said that, it seems that most brewers are able to get at least 70% efficiency.

The responses so far are (these may get updated ahead of my comments below):

Brewboard voters results.

So what conclusions can one draw from this? Among the respondents:

• Regardless of sparging method, most brewers achieve over 70%.
• Half of all spargers get in the range 70-80%.
• Batch sparging is more popular.
• Fly spargers tend to have a tighter range of efficiency.

• Fly spargers are a few percent more efficient. See more below.

• High efficiencies are attainable with both methods.
• The distribution for batch spargers has quite a tail on the low end. One could speculate several reasons for this:
  • The batch sparging process is inherently variable (not sure about that).
  • Perhaps batch spargers tend to be less experienced. Less experienced brewers might not yet have a good handle on how to extract the best out of their system.
  • Maybe the range of equipment that batch spargers use is more varied.
• If you exclude results below 65% (I chose this in an attempt to factor out the tail) then now you have batch and fly spargers at almost the same efficiency.

After running this poll, I ran similar questions on AHB topics batch and fly. I had to separate them because AHB is configured for a maximum of 10 questions per poll.

The AHB results.

The raw data.

The combined results. You can draw your own conclusions from this, I am off to pour me a beer.

My Efficiencies

This is a plot of my mash efficiency over time with the equipment and method described on this page. The Stout02 point was definitely a flyer - the mash bed didn't settle properly during the mash. At WA_APA_5 I had increased the gap on my RollerMill with a view to speeding up runoff (sacrificing a little efficiency).

The big efficiency dive at the end turned out to be a badly adjusted grain mill. The gap was to 1.4 mm when I measured it after the second flyer. I have set it back to 0.9 mm.

This is a plot of my efficiency vs mill gap.

Loss To Grain

I have been reasonably happy with my consistency re volume into kettle but if anything, my volumes are generally a bit short. At the outset I plugged 1.10 L/kg into Brewsta since that is a figure that gets thrown around quite a bit (if my memory serves me correctly).

After brewing a few beers, I was curious to go back and check my assumptions so I fitted a curve to my gain-mass vs mashtun-losses and found that mine is more like 1.1 L/kg plus approximately a constant 1 litre (the dotted line). This adjustment will give me another litre in the kettle and pretty bang on for most brews.

The outliers are possibly due excessive drinking on brewday.

BrewHouseStats.pdf contains a more up to date discussion, including the dramatic drop in efficiency when my mill gap was set too wide.

Vermont Fuel and Produce (Melbourne)

This info has moved to VermontFuel (these guys sell PowellsMalts by the bag).

paul sorenson