New Equipment - Having a hard time hitting preboil gravity

[jeffdunn]

Most of my brewing for the past couple of years has been single infusion mashing with batch sparging. Using recipes and Beersmith I rarely had difficulty hitting all of my numbers (pre boil volume, pre boil gravity, volume losses from deads pace and boil, etc...).

This winter I built a three vessel system that uses propane burners for strike water and the boil kettle and a RIMS systems for a recirculating mash. I've only brewed 4 times on the system but there's a consistent issue that has been happening each time. When I meet my preboil volume the gravity is too low by about 4 points. Not the worst thing in the world, I just boil a little longer but then I'm a little short on my post boil volume.

Not sure what's happening but here's what is new to me:

• I've started crushing my own grains with a new grain mill (a finer crush than the homebrew shop).
• The RIMS system lets me recirculate the mash, which I do for the entire mash.
• Transferring wort/hot liquor with pumps and silicone hosing.
• Boiling with propane (I confess to also having issues with finding the sweet spot for the boil, my evaporation rates are kind of high from what I'm used to on a stove).

I'm kind of confused about where to start troubleshooting. With a RIMS I shouldn't have to add more malts to the mash to get the volumes I want right? Is it the grain to water ratio? I've been using about 1.75 qts/lb.

I'm wondering if when I'm recirculating with the hose if it's just shooting straight through the grainbed in one location and not getting an even flow through the entire volume of grain. I don't have a sparge/recirculating arm/nozzle just the end of the hose aimed in the mash tun.

I know a lot of this is just getting familiar with new equipment but I expected greater sugar extraction not less. Thanks in advance Y'all.

 

[day_trippr]

How are you sparging? If fly sparging you may be channeling a short cut through the grain bed...

Cheers!

 

[jeffdunn]

I just have a hose hanging over the edge...I think you're right because after draining the tun there was large circular depression in the middle of the grains. I'm guessing some kind of recirculating nozzle that gives a more even distribution of recirculated wort is where I want to focus.

 

[Beardless]

I’ve brewed a couple times with a new HERMS system and had good success. I finally started to crush my own grains my last brew and lost a lot of efficiency on that one.

I have one of these that I bought from MoreBeer (although it looks to be made by SsBrewtech):
‭

it seems to work well, although when I’m cleaning up after a brew day some of the holes seem to have grain in them, and I wonder if it is hurting my recirc; but I’ve had good efficiency with it previously.

I had set my new mill with a credit card, as I’ve heard that is usually pretty good. The crush looked ok to me and was creating a pretty good amount of flour, so I didn’t think anything was wrong until my preboil was extremely low. Afterward I milled a bit more and compared it to some grain I had milled previously at the LHBS- I reset my gap even smaller. Planning to get some feeler gauges to check the gap for certain.

All that to say- I think you’re onto a couple of reasons you may have had low extraction, or even a combo of both. I’d double check your crush and also check on the channeling issue by spreading out the return flow or using the other techniques (cutting the bed, etc). What is at the bottom of your MLT, screen, false bottom?

Edit: made more clear when I started losing my efficiency

 

[bracconiere]

I just have a hose hanging over the edge...I think you're right because after draining the tun there was large circular depression in the middle of the grains. I'm guessing some kind of recirculating nozzle that gives a more even distribution of recirculated wort is where I want to focus.

i just use a colander...

 

[day_trippr]

fwiw, I use a Blichmann autosparge valve which comes with a length of 3/8" ID silicone tubing and a stainless steel float ball. After some experimentation I was able to position the float ball so the end of the tubing is just submerged under the surface of the wort. With around 1-1/2" to 2" of wort above the grain bed I can recirculate at between 2-3 gallons per minute without carving into the grain. Makes fly sparging both easy and effective. I typically run around 80% BHE with mash efficiencies in the low 90s...

Cheers!

 

[FunkedOut]

The false bottom / pick up point / manifold at the bottom of your mash tun is just as important, if not more than your return manifold. Both need to spread the flow to avoid channeling.

Next you need to figure out if you have a conversion problem or lauter problem. Search conversion effeciency vs lauter effeciency.

What’s your recirc flow rate?
What’s your flow rate when draining to kettle?

But first step in troubleshooting is be absolutely positive your volume markings are accurate.