Opinion needed on flow rates for Vorlauf and Fly sparge using a pump.

Hi All,

My brother has been showing me how to brew AG batchs in the last month. The setup he have include a pump to help with the transfer of the wort all over the process (mash, vorlauf, lautering, vortex and cooling).

We had some problem with the latest batchs since the OG pre-boil and post-boil are way below the estimated, resulting in a poor effeciency. After some researchs, I strongly beleived that we've been doing our fly sparge way too fast.
Here's an overview of our mashing and lautering steps. After the conversion time is complete, we are using the pump at full flow rate to do the vorlauf of the grain bed until it run clear. Afterward, we connect the kettle containing the sparge water to the pump and we do the fly sparge at around 50% of the flow capacity. The process takes 20 to 25 minutes... Like I said, I beleive that it's way too short and we should reduce the flow so the sparge takes 60 min or so...

Now I've read on many forums and over the internet that there's no flow limit for the vorlauf using a pump but that using a fly sparge process should be done pretty slowly to prevent channeling in the grain bed.

What is your homebrewers opinion on the fact that using the full flow for the vorlauf could start the channeling of the wort in the grain bed even if we reduce the flow afterward for the fly sparge? Do you think or know if we should adjust the flow of the entire vorlauf/lautering process or keep the full flow for the first part as describe and just reduce the flow afterward?

Thanks for your opinion.

What's your batch size?

Fly sparging should like you say be done slowly.

You say you've had some problem during the latest batches with low extraction efficiency, so I assume that you've been hitting your targets in the past? Has anything in the setup or process changed? Or change of malt/maltster?

Until now, I've done 4 batches of 5 gal in volume each with my brother.

What he told me is that those last batches were done with the adjusted equipment setup and they were all off the estimated OG.
He also said that the 2 batches before these lasts 4 were done with the same equipment but he encounter some problem with the runoff when doing the vorlauf & sparge so he had to go slowly and was always on the target OG. To prevent these stuck runoff, he adjusted the mash tun by adding an additional filter at the bottom. Typically, it is the only thing that changes in the setup and process.

Do you think that we should keep the same flow rate for the vorlauf as what we'll used for the sparge?

It makes sense to me to have both at the same rate due to setting the grain bed...

Before I got to know my latest setup I recirculated with full speed, but for the entire mash. I got terrible extraction, when i choked the pump it got all good.

A stuck runoff can also mean that the recirc rate was to high, and the grain bed compacted way to much. If that's the case then there shouldn't be any need to add another filter, just slow down the recirculation. The grainbed should be the filter, the FB (if that's what you're using) is just something to keep the grains above the bottom.

I use this type of setup with the only difference being I recirc the entire mash time through a HERMS coil in the HLT. This recirc (same as vorlauf at the end) is done at a pretty slow flow rate, maybe 10% of the pumps capacity. I run it slow as to not compact the grain bed and avoid channeling. When I start fly sparging, I use a Nalgene bottle (a large measuring cup will do) and I time the outflow of the mash tun to be .8L/min and this allows me to dial in the lauter rate and repeat it every batch and reach my numbers. The sparge water I just try and keep it at a relatively consistent flow rate but don't bother measuring.

20-25 mins is likely too fast and you need to slow down. A good target is not more than 1L/min, but every system is different so you just need to dial in what works for you and what your expected efficiency is in your recipe to hit your Pre-boil numbers.

I do single infusion mashes and recirculate for about 15 min or so (vorlouf) with my pump while I wait for my sparge water to get up to temp. I then fly sparge from a HLT and pump from the MLT directly to the BK. This process takes about 45min-55miin for a 10 gal batch and I have consistenly netted over 77% efficiency.

You can vorlouf at 50% starting off and then up it to 100% until you run clear. After you are running clear, open both valves to ~25% and see how that rate works out. Honestly, playing with the system and finding what works and what doesnt was the best way I upped my effiency. What kind of mash tun do you use? If its a cylindrical type, are you using a dip tube?

pvault98 said:

...20-25 mins is likely too fast and you need to slow down. A good target is not more than 1L/min, but every system is different so you just need to dial in what works for you and what your expected efficiency is in your recipe to hit your Pre-boil numbers.

Click to expand...

Huh? would 25 minutes not be perfect for a 5 gallon batch (lets assume collecting 6.5 gallons pre-boil) at 1L/min?
6.5G is just under 25 litres

20 mins too fast, 25 mins could be just about right depending on Pre-boil volume at that amount. My system boils off 1.5 gallons per hour and I usually have about 5.5 - 5.75 gallons in my kettle at the end to account for system losses to trub, hoses, and the plate chiller so even 25 mins is cutting it pretty close. Again it is system dependent, in my case it takes no less than 30 mins, hence 20-25 mins is "likely" too fast especially if his efficiency seems to be suffering.

Even 25 minutes sounds like really fast for a 5gal batchs considering that we use a 6 gal plastic bucket for mash tun.

I'll try to do the vorlauf at a third to half flow capacity of the pump and adjust the collecting flow so it takes at least 45 to 50 minutes... It should keep any channeling from occuring during the vorlauf.

I'll definitely needs to build myself another fly sparge arm... I'll keep you guys informed on the next batch efficiency!

I second (third, whatever) that 25 minutes for a 5g batch is too quick.

Fly sparging works by diffusion, sugars are absorbed by the sparge water, they move from higher denser suger area to a lower denser sugar aree (the sparge water). This takes time.

But also, although I have a feeling this is not the issue. If the brews were with a over 50% wheat, that might take away 5% of efficiency.