Need Schooling on HERMS Fly Sparging

[DeNomad]

I would like some feedback on my fly sparging technique, my resulting efficiency has varied from 66% to 90% over 5 batches. I have been a batch sparger for 5 years but I retired my cooler MLT this year - it was time, something nasty grew in the insulation. My batch sparging efficiency was very consistent ~78%.

Anyway I have ran 5 batches through a keg MLT with a false bottom and a silicone tubing sparge arm which lies on top of the grain bed. My basic technique follows BierMuncher's Hybrid Fly technique as listed in this thread and my sparge arm is shown below.
https://www.homebrewtalk.com/showthread.php?t=75454

I do not think my grain mill needs adjusted, it is set at a gap of .032" and I haven't changed how I handle my water with batch sparging so I am at a loss for the inconsistent efficiency.

My steps are this.
- Pre-heat MLT to desired temperature required for step temperature. Add grain. Water:grain ratio is 1.25 quarts/lb.
- Recirculate my mash through my HERMS coil for an hour at the step temperature (151-156 F depending on the beer). I use a march pump with the valve fully open for this.
- About 45 min into the mash I stop recirculating the mash and crank the heat on the HLT to reach 185 F
- At 60 minutes I stir mash quickly, vorlauf using a march pump
- I begin sparging with the 185 F water from the HLT with a march pump throttled down as low as I can get a trickle of water to flow. My sparge arm is a piece of silicone tubing which I lie on top of a plate. I may try using a lightweight pie plate rather than a ceramic plate next attempt as the heavy ceramic plates tend to sink into the grain bed.
- The result is about 165-170F water in the area around the sparge arm - basically my lazy mash out and fly sparge at same time. I do this as I currently only have one burner and don't want to move the HLT until it is nearly empty.
- Use march pump #2 to drain the wort slowly into the BK. I try to match the flow rates by eye and keep ~2-3" of water over the grain bed.
- I use the sight glass on my HLT to eyeball when to stop adding water. I try to end with a dry mash with just the right volume in the BK - perhaps this is my issue?
- Allow the BK to continue to fill. I pump at about 1 quart/minute so it takes around 30-40 minutes to sparge a single batch or around 80-90 minutes for a double batch. Check pre-boil SG and see how hard I need to boil or if I need to add water to dilute.

I am unsure if my sparge arm is causing channeling or if I should continue adding extra water to the mash in order to keep the grain bed from compacting. I could use a bit of advice as I am liking how hands off fly sparging is especially with the double batches but I need to be more consistent. I have read that many are happy with silicone tubing sparge arms.

 

[Homercidal]

If you have that much water on top of the grain bed, then I doubt channeling is an issue.

Honestly, I don't see a problem, but I haven't yet started fly sparging. I'm still batch sparging, but have thought about switching once I get a HERMS set up.

 

[pinchegil]

I fashioned my like the electric brewery does it is simply a long piece of silicone tubing with nothing on the end. putting something heavy on the end will make it work its way down into the bed. I would think A plate on the top of the mash bed would block part of the top of the grain bed and possibly cause channeling. I took a 4 foot piece of silicone in my 16 gal mashtun and curl it around the outside of the tun, then I curl it on top of itself, then I set the pump, and the trickle where it keeps about ann inch or two of wort above the grain bed, never letting the top of the grain bed to get dry. look at the electirc brewery mash tun page

 

[day_trippr]

I do exactly the same as ^that^ - just bare 1/2" ID silicone tubing looped around the inside of the MLT, keeping a fluid cap atop the bed. I'm not sure one could predict what's going on with an elbow weighting down the business end of the hose.

Wrt to the OP, with a recirculating mash system there's no reason to stir the mash before sparging.
All that does is disrupt what's already a nicely formed bed.

Also, a 30 minute fly sparge for a five gallon batch might be too short.

Could the extraction variability be due to crush variation?
Do you crush your own grain?

Cheers!

 

[DeNomad]

Thanks for the feedback everyone. I do crush my own grain and my mill is set to a .033" gap. I do not anticipate the mill adding to the variability. I think I will remove that elbow and put a longer hose on which wraps around the inside.

I am curious how everyone is able to get such large sparges. I am told to aim for around 1 quart/min (or 8.5 gallons in 35 minutes). Having the valve on my march pump discharge open just a crack (~10%) I am barely able to throttle the flow rate down that much.

 

[jddevinn]

I too just have a hose laying on the top of my grain bed.

Sparge rage is 1 gallon every 5 minutes (7 gallons in 35 minutes) I use two cheap flow meters from ebay to set the flow rate.

 

[DeNomad]

Thought I would report back on this thread. My last brew day was much more predictable. I took advice offered and removed the elbow and short hose on my MLT and replaced with ~4' tubing which wrapped around the inside two times. Also I inspected the gap on my grain mill. I found that it had opened up on one side. I haven't checked it in about 4 years, I suspect the occasional grain sized pebble in the 2 row forced the rollers apart.

Either way I re-gapped to the rollers to .030", I found the crush to be much more fine. Although hard to get the grains going sometime. I sparged nice and slow (75 minutes for a double batch) and got 78% efficiency on a 11 gallon batch of belgian quad. Worked great and that was about what I expected.

 

[day_trippr]

Excellent, glad to read this. The mill gap opening up on you probably was the larger influence on the varying extraction rates...

Cheers!

 

[universalfrost]

Good reading here...I was having a similar situation with random sg numbers ....head over to check my rollers on the mill now....