Post
by John G » Sat Nov 07, 2015 12:11 pm
If you are using the false bottom and recirculating your mash and you're getting stuck mashes and low or all-over-the-place efficiencies, you may want to look at your roller mill gap and your water:grain ratio, which was what I figured out for my HERMS system. My mill gap was around 0.035 and I was using 2L/Kg mash water/grain ratio in my former batch sparge setup. With the HERMS system, this lead to difficulties getting the water to flow, stuck sparges, and efficiencies that ranged from 68 - 74%, and totally unpredictable. For recirc HERMS, it's a bit counter-intuitive, but wider mill gap and higher water:grain ratio improves efficiency. I think it has to do with the fact that more water means the grains are flushed through better than with a lower water:grain ratio. The higher mill gap helps with water flow as well.
My current settings are a 0.045" mill gap and 3.13L/kg water:grain ratio. This gives me a pretty consistent 85% efficiency with the pump running full flow. Prior to that with smaller mill gaps and lower water:grain ratios was super frustrating both in terms of the brewing process and hitting my numbers. Not sure if this will help, but good luck dialling in your system. Enjoy the process!
Edit: I also forgot to mention that I add 2L to my mash tun first, and then calculate water:grain. That 2L is just the void below the false bottom in my keggle and I exclude it from my calcs. I also have to add 3 L to my total boil volume to end up with the same final pitch volume since my kettle leaves behind more liquid compared to when I gravity syphoned it out in my old propane burner heated kettle. I currently pump out of my kettle through a plate chiller to my fermentor and lose about 3-4L from hops and leftover liquid in the kettle.
