[BrewBama]

Does one have to underlet slowly?  If so, how slow?  My HLT is raised above the MT, so I gravity drain.  Would that be slow enough?  It would be nice to have fewer dough balls, and better LDO.

I’ve found that underlet pumping from the HLT to the MLT (Coleman cooler) slowly does eliminate dough balls in my system.

How slow is a good question. I have a linear flow valve to control pump volume accurately that I open to 1/4” measured from the machined seam on the housing to the edge of the adjustment cap. I have no idea what that gap setting translates to in volume over time. However, it seems to wet the grain in a very controlled uniform way.  I gently stir to check but since doing it this way I’ve yet to find a dough ball.

I use the same gap setting every time I mash in. I also use the same setting to recirculate during the mash and to transfer to the BK after the mash. 

Once mashed in, I am at a slightly lower temp than mash in temp. I allow the RIMS to bring me up the ~5 degrees to the mash in temp as I begin the mash recirculation.

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[goose]

Although I could underlet from my HLT to my mash tun,  I just gravity fill my mash tun with the required amount of liquor (my HLT is higher than my mash tun), heat it to strike temp and stir in the grain.   Now I admit I am not a LODO brewer, but it makes things easier for me and I always hit my mash temp target.

If I ever decide to build a new brew system, something that has been bouncing around in my head like a BB in a boxcar, I might consider a setup that would allow me to underlet with a pump.

[Big Monk]

Does one have to underlet slowly?  If so, how slow?  My HLT is raised above the MT, so I gravity drain.  Would that be slow enough?  It would be nice to have fewer dough balls, and better LDO.

If you are doing as a piece part of a system whose goal is to help exclude oxygen, then slower is likely better so as to to not suck air in the HLT vessel, through connections, etc. Slower means better mixing without having to stir, which is also important for that specific goal.

If that's not the goal, then speed shouldn't matter, especially if you are just going to stir it up real good anyway.

[coolman26]

I’m finally back to brewing regularly after a long hiatus. I made a lot of changes to my rig. I’m a cooler MT user. I found that pumping into my grain makes it easier. No doughballs at all. I went back to using my HERMS, and continual recirculation. Loving the results with underletting, just easier for my process. 


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[soymateofeo]

I used to underlet until I went the herms route.  I can't see an easy way to recirculate and get that dope grain bed that makes my wort Oh-So-Clear.

[yugamrap]

I used to underlet when I mashed in a cooler.  I found that it helped minimize dough balls, but I still had to stir a bit to help equalize temperature throughout the mash.  These days I'm using a HERMS, so I'm adding the grist to the strike water and stirring gently.  The HERMS does the temperature equalization, and I return the recirculating wort via a submerged manifold to minimize oxygen contact and agitation of the grain bed.

[charlie]

I'll have to try that next brew (which is an Irish Red Ale happening on 11/18). I suspect that the HLT will fill more slowly, but all I have to do to set it up is run the hose to the ball valve, so no big deal.

OK. I did it today. I fed 7 gallons of water at 167F water into the MT with the 20 lbs of grain already in it. Truth is, I don't think it made a lot of difference. It's true that I didn't get any dough balls, but I still had to stir the slurry to get a a consistent thickness.

The MT did seem to hold a more even temperature after mash-in, and I suspect that the grain was treated more kindly because of not being dumped into 7 gallons 167F water. We'll see.

Charlie

[goose]

The MT did seem to hold a more even temperature after mash-in, and I suspect that the grain was treated more kindly because of not being dumped into 7 gallons 167F water. We'll see.

Charlie

I used to worry about this as well, Charlie, but I have never noticed any conversion problems by stirring the grain into 167 degree liquor (again I am not a low DO brewer here, yet!).  I start my recirc. within about 5 minutes of dough-in (RIMS system with false bottom mash tun) which is probably not necessary but it does give the mash time to settle a bit before starting the recirc and allows the pH to stabilize. The only thing that stays a bit warmer is the foundation water, but when I measure the temp of the mash with a thermometer before recirc, I always hit my desired temp. and the temp of the foundation water stabilizes pretty quickly.  A wise man has said, RDWHAHB! 

That said, I am curious about your observations.

[trapae]

I underlet.   I have the SS brewtech tun,  but should be the same for a cooler.