Fly Sparge First Runnings- Drain or Not?

[micraftbeer]

I'm experimenting with a few of my processes for different reasons. I brew in a 2V setup with a mash lauter tun constantly recirculating through a RIMS, then I transfer to a boil kettle. I have been batch sparging, but just recently decided to wander back to fly sparging.

On fly sparge, I've read people do it different ways with respect to keeping the grain bed submerged during the sparge. Some collect the entire first runnings (draining all the wort), then fill sparge water to be above the grains, and keep it there, until finally collecting the necessary boil volume. I did it this way on my last batch and had 88% mash efficiency as compared to what normally I'd get 79% when batch sparging. So it seemed good.

But I've also heard some people never let the grain bed go dry during sparge.

Does anyone have a science/chemistry explanation of why one way would be superior to other? Or personal experience between the two that has driven you two do it one way vs the other?

 

[day_trippr]

Fly sparging is supposed to be a hydraulic process that keeps the grain bed "fluid" while forcing sugar-rich wort out the drain via hydraulic pressure. Fully draining a mlt can cause the grain bed to compress and shrink leaving a gap between grain bed and kettle allowing easy channeling, or simply create a tight bed such that a subsequent fly sparge may seize up requiring stirring - which pretty much defeats the whole point of fly sparging.

fwiw, I drain just enough wort from the mlt to bring the fluid level barely below the top of the grain bed, then set my autosparge to calmly bring the fluid level back up to 1-2" above the top of the grains, then run out at a quart per minute...

Cheers!

 

[doug293cz]

...Some collect the entire first runnings (draining all the wort), then fill sparge water to be above the grains, and keep it there, until finally collecting the necessary boil volume. I did it this way on my last batch and had 88% mash efficiency as compared to what normally I'd get 79% when batch sparging. So it seemed good.
...

This is a batch sparge. If your efficiency changed, then something else is causing it.

Brew on

 

[kevin58]

" On fly sparge, ...Some collect the entire first runnings (draining all the wort), then fill sparge water to be above the grains, and keep it there, until finally collecting the necessary boil volume."

You just described a batch sparge not a fly sparge.

 

[doug293cz]

This is a batch sparge. If your efficiency changed, then something else is causing it.

Brew on

" On fly sparge, ...Some collect the entire first runnings (draining all the wort), then fill sparge water to be above the grains, and keep it there, until finally collecting the necessary boil volume."

You just described a batch sparge not a fly sparge.

I've been thinking about this, and while at first, OP's method sounds like a batch sparge, it isn't really. OP continues to add water during the sparge run-off to maintain water above the grain bed. It sounds more like an interrupted fly sparge. How well it works will be heavily dependent on how slowly the sparge water is added after the initial draining, an how evenly it is spread across the surface of the grain bed. If adding the sparge water disrupts the grain bed significantly, then OP's process becomes more like a batch sparge. If it doesn't disrupt the grain bed, and trickles evenly throughout the grain bed, then it is more like a fly sparge. The difference to a traditional fly sparge is it will take longer, and have a greater chance of a stuck sparge (as the grain bed will have compacted during the initial run-off.)

Brew on

 

[micraftbeer]

OK, here's some more info. I guess it is kind of a hybrid- or as @doug293cz described it, an interrupted fly sparge. I had read somewhere (don't remember where) that suggested the process of collecting the entire first runnings before doing the continual fill/drain phase. The logic was that the first runnings were the most dense with sugars, so to get the most efficiency, you drain that off, and then the rest of the sparge is less saturated, and able to extract more sugars.

With the constant RIMS recirc during the mash, I had a good grain bed. Draining off the wort of first runnings took about 5 minutes. I then shut off the pump that was draining and then slowly filled the mash tun with sparge water via the Autosparge, with the hose laying on top of the grain bed. Slowly filled it to about 1-2" above the grain and let it continually flow in & out. The wort slowly became more clear as I spent the next 20 minutes collecting the 8 gallons of pre-boil wort. I had no issues with stuck mash.

 

[doug293cz]

OK, here's some more info. I guess it is kind of a hybrid- or as @doug293cz described it, an interrupted fly sparge. I had read somewhere (don't remember where) that suggested the process of collecting the entire first runnings before doing the continual fill/drain phase. The logic was that the first runnings were the most dense with sugars, so to get the most efficiency, you drain that off, and then the rest of the sparge is less saturated, and able to extract more sugars.

With the constant RIMS recirc during the mash, I had a good grain bed. Draining off the wort of first runnings took about 5 minutes. I then shut off the pump that was draining and then slowly filled the mash tun with sparge water via the Autosparge, with the hose laying on top of the grain bed. Slowly filled it to about 1-2" above the grain and let it continually flow in & out. The wort slowly became more clear as I spent the next 20 minutes collecting the 8 gallons of pre-boil wort. I had no issues with stuck mash.

The reason for running a "normal" fly sparge slowly is to minimize the mixing of the sparge water with the mash wort. In this way the high SG mash wort drains out first, followed by sparged wort with ever decreasing SG. And, you minimize the possibility that the mash bed will over compact and get stuck.

Brew on

 

[bracconiere]

How well it works will be heavily dependent on how slowly the sparge water is added after the initial draining

i usualy let my fly sparges drain. not completly, but mostly, then fill up the mash tun above the grain bed, wait 20 minutes. fly sparge...slowly...i've seen similar to @micraftbeer results.....

an interrupted fly sparge.

i do that all the time...

- or as @doug293cz described it, an interrupted fly sparge.

wait, he has charts on just what you can expect from how often it's interupted? i'm surprised he doesn't have a chart for usual mash temps and sugar dilution and how it occurs at what temp and exactly how fast to fly sparge! (i think he's into excel'ing )

 

[doug293cz]

i usualy let my fly sparges drain. not completly, but mostly, then fill up the mash tun above the grain bed, wait 20 minutes. fly sparge...slowly...i've seen similar to @micraftbeer results.....


i do that all the time...





wait, he has charts on just what you can expect from how often it's interupted? i'm surprised he doesn't have a chart for usual mash temps and sugar dilution and how it occurs at what temp and exactly how fast to fly sparge! (i think he's into excel'ing )

Almost all my charts and spreadsheets are for static/equilibrium processes. A lot of what goes on with brewing, including fly sparging, are dynamic processes. Modeling dynamic processes requires working with differential equations, and I don't do that any more. Also, any dynamic process modeling usually is only applicable to the specific system it was done for, so generalized solutions are not usually possible.

I don't have charts or spreadsheets for the items @bracconiere mentioned above.

Brew on

 

[bracconiere]

I don't have charts or spreadsheets for the items @bracconiere mentioned above.

Brew on

but we can agree if he's only passing a gallon every 20 minutes for a total of 6 gallons, it should be kept above the surface? and not fly sparged on a 'hybrid' batch sparge of drained malt???

(and i know even though, you 'not anymore' you could.....alltitude, pressure of how much water depth of mash tun and water over bed, temp of sparge water, solubility of sugar in said water how fast the run off was!!....i've seen you do it! i swear! )

edit: and i've seen that batch sparge chart so many times with how many times, and how good it would be!

 

[bracconiere]

https://www.homebrewtalk.com/threads/sparge-time-vs-amount-of-grain.671999/#post-8714987
come'on doug, if you can that for batch sparging we need you for fly sparging! lol

 

[BigJay13]

I listened to an MBAA podcast a few months ago that spoke about efficiency in the mash and they described something similar, IIRC. Now, they have much bigger vessels so take this with a grain of salt. They partially drain the mash tun until they can't see any liquid anywhere over the grain bed--they said it left about 25% of the liquid in the mash--then they slowed the outflow and filled up to normal sparge depth. So first 3rd the ran off fast, second 3rd went slow, and for the last 3rd they went fast again. This didn't sound like they let it go as fast possible--more like 110%, 80%, 110%--for an average of 100%. It was pretty interesting.

Here it is: Brewhouse Efficiency for the Small Brewer

If I had any of those pieces mixed up please correct me! But you get the idea...

 

[doug293cz]

I listened to an MBAA podcast a few months ago that spoke about efficiency in the mash and they described something similar, IIRC. Now, they have much bigger vessels so take this with a grain of salt. They partially drain the mash tun until they can't see any liquid anywhere over the grain bed--they said it left about 25% of the liquid in the mash--then they slowed the outflow and filled up to normal sparge depth. So first 3rd the ran off fast, second 3rd went slow, and for the last 3rd they went fast again. This didn't sound like they let it go as fast possible--more like 110%, 80%, 110%--for an average of 100%. It was pretty interesting.

Here it is: Brewhouse Efficiency for the Small Brewer

If I had any of those pieces mixed up please correct me! But you get the idea...

The linked podcast does not cover the fly sparge process described in the post above.

Also, if you listen to this podcast, you need to know that they define brewhouse efficiency as pre-boil efficiency (what BeerSmith and others call mash efficiency.) Brewhouse efficiency as used by BeerSmith, Brewer's Friend, and others means efficiency into the fermenter, which includes the effects of transfer losses between the BK and FV. If you don't realize the terminology conflict, you may get a bit confused.

Brew on

 

[BigJay13]

We’ll shiiiiiiiiit….I’ll listen to it again! Sorry for the confusion

 

[BigJay13]

This was the one I was thinking of:

https://podcasts.apple.com/us/podcast/master-brewers-podcast/id1156748005?i=1000427141807