I wasn’t able to find an answer to this with Google or elsewhere in this forum and others, so here I am.
Recently, I saw a video where a professional brewer started recirculating through the HERMS system BEFORE mashing in. IE:
Heated water to just above mash-in temp in HLT
Moved strike water to empty MLT
Began circulating water through HERMS at mash-in temp
Added grain (mash-in)
Continued circulating through HERMS until moving to boil kettle
Has anyone else done this on the homebrew scale? I have been fighting my RIMS system a bit with getting a good grain bed, as the grain bed doesn’t really stratify well - I get A LOT of flour through the pump, and the grain bed gets shallow about the edges of the MLT.
It seems like this method of running through the HERMS (or, RIMS in my case) could help keep the grain bed very consistent as grain is added to the MLT.
I’m trying to accomplish two things with this post:
Figure out why my grain bed settles the way it does - terrible drawing below. I know the reason I have particulate passing through the pump is the grain bed is very thin at the edges of the MLT.
Determine if the mash-in technique described in my original post is common or not, and find out from someone who has done it how reliable it is.
“Underletting” means adding liquor to the mash tun from the bottom of the tun as you are doughing in. In other words you are filling the mash tun with strike liquor from the bottom as you add the grain. A lot of professional brewers do this as it cools the hot liquor from the strike temp to the mash temp as you are adding the grain. I don’t use this method at home. I just heat the liquor to the strike temp and stir in the grain. I can normally dough-in in about 3 minutes or so and it is easier to keep dough balls from forming in the mash tun.
With regard to your wort clarity, I too am wondering if you have to fine a crush on your grain and/or if you pump is pulling the wort too fast. If you have a valve on the output of the pump/HERMS coil, you can slow the flow down a bit and maybe clear the wort. I have a RIMS system and the wort runs clear after about a minute or two of re-circulation. I start the recirc. about 5 mins into the mash to allow the bed to settle a bit and it works fine. I then recirc. for the remaining mash time. This technique should work the same with a HERMS system. You might look at these options to see if any or all will help.
Let me know what you discover. I am curious to see if your results change.
I brew on a RIMS system - Brew-Magic. Here’s my procedure.
In the Mash Tun, I move my inlet tube to rest right at the false bottom. I then pump over just enough hot water to cover the false bottom about 1/4 inch. Then I add in all of my milled grain (I run a 3-roller mill at about 0.4 inches with fairly complete husks and very little flour). Next, I very gently pump over until I hit my required mash volume. This has the effect of hydrating the malt from the bottom and pushing up all of the air trapped in the grains. I’ll do a very short and gentle stir, just to make sure no dough balls have formed (usually do not with this method), and then move my inlet tube to rest about an inch below the mash level. Lid on.
I set a timer for 10 minutes, and setup the valves to recirculate. After ten minutes, I start to pump very slowly. Every 5 or so minutes I increase the circulation rate but seldom go above about 75% of my throttle valve’s fully open state. Circulation continues through any steps or mash out. I gravity feed the wort to the kettle, reset the valve configuration for lautering and do a slow sparge (valve never gets above 25% open) for about 45-50 minutes.
If my mash is floating up, air is getting under it and my valves are setup wrong. If I circulate right after grain in - I risk compacting the mash and sticking it, as well as getting excessive flour and other bits into the pump. By letting the mash rest and more fully hydrate, I get consistent results.
Transfer over about 1-2 gallons of water to the mash tun allowing the mash tun to preheat, therefore
reducing the cooling when transferring all the strike water.
Transfer all the desired strike water and pump through the HERMS (You need water in the HLT for the HERMS
coil to transfer heat to the mash water - don’t empty the HLT).
Add grain to mash tun once strike water is stable and at the proper temp.
Start recirculating the mash at a trickle and adjust flow rate to stabilize the temp. PID controller on the HLT is
set 2-3 degrees above the intended mash temp. A small flow rate will overcome the cooling losses and
maintain the correct mash temp, while setting the grain bed and clearing the wort.
Interesting problem this AM with my mash recirculation: I kept cavitating my pump and thought of this thread. Oh, it helps if you remember to install the false bottom, as well. I suppose it acts like a grant so the pump pulls on the liquid vs. pulling on the grain bed because once installed = no more problems.
