False Bottom Options for Direct Fire Mash Tun

[gifty74]

I have a converted keg mash tun with Midwest Supplies mash screen and homemade dip tube to pull from the center (underneath the screen, pics attached). I've been having issues with flow slowing to a trickle during mash recirculation. I had to go in and rouse/scrape the screen during mash to free things up. In the future I do not want to have to worry about how fast I'm pumping, flow slowing, stuck mashes, etc. I had been mashing in a cooler with a manifold that I slit to allow flow and could run that at full pump speed and never had an issue with flow slowing or sticking the mash. A manifold would be a problem with my new direct fired system because the grains are laying right on the bottom of the kettle with no false bottom.

What is everyone using, and are having any issues with flow during recirculation?

I don't want to go to a RIMS tube, but that seems like an option here. Any other thoughts?

 

[piper55]

That screen looks small and fine, I have a sabco I covers the whole dome of the keg it only clogged once but I had 40 lbs of grain in it. the only other thing maybe is you are grinding to fine maybe

 

[gifty74]

Good point, I need to check my barley crusher gap again, but I don't have it crazy tight. The holes are not that small, but I could see some grain getting lodged in it, but when I cleaned it out there wasn't that many grains lodged in here. I did have 32 lbs of grain so it was a lot. I resolved it by scraping the top of the screen near the end of the mash, and then it seemed to flow ok, but just don't want to have to worry about it.

 

[Golddiggie]

Not an issue with my Jaybird/NorCal FB... It also covers the entire bottom of the keggle (full diameter), has a hinge and handle to make it easy to install/remove.

Something you can try, for cheap (before replacing the FB) is adding rice hulls to the mash. Crush your grain as normal. Add half of it to the mash tun, dough-in, then add the rice hulls, dough-in and then add the remaining crushed grain, and get that mixed in. 6-8oz with a grain bill up to 28# works well for me. Just don't run the rice hulls through the grain mill.

 

[AKnewbrews]

Heres is how I did mine with a Blichmann false bottom.

https://www.homebrewtalk.com/f11/false-bottom-adaptation-239875/

 

[mredge73]

Mine is very small (8") and I don't have that much trouble with circulation even with high wheat mashes. I always run off a few gallons with a pitcher first to make sure no grain is coming through to clog the lines.
You may just have to increase your water per lb ratio if you are continuing to have trouble. I am currently using .135 gal/lb for batch sparge; and I have been experimenting with no sparge (and I like it).


Aside,
I used mine as a direct fire mash tun for a while but I could not get my burners tuned to where they provided sufficient heat but not so much as to scorch the wort.
I chose to go with a RIMS tube because I decided that I just wanted a set and forget method that was reliable.
If you cannot correct your issue and decide to go with a RIMS tube http://www.stainlessbrewing.com/ has a great deal on one. I built mine for twice the price.

 

[gifty74]

So with the RIMS tube you have been much happier? I haven't scorched the wort yet, and that was only the initial run to try and figure things out. I don't think scorching will be an issue, more worried about compacting the grain bed. I guess it didn't do too bad with 32 lbs of grain and 1.25 qt/lb water ratio. Just need to get recirculation going slow, and not have it running too fast at any one time. With a RIMS tube you can go to a manifold, which in my cooler worked so well, NEVER slowed flow or stuck a sparge. Just reading about the RIMS tubes though and they sound like they are a bit of a hassle to clean/maintain. Also, if you have the temp probe in the one end of the tube, and the heater in the other, isn't it going to have the same problem as my setup now, where the heated water gets read by the probe on the way back to the recirc port, and shows 160-170F like right away, and shuts off the heater due to hitting the out of range high set point?

 

[mredge73]

I scorched the grains and wort more than once on mine by getting the bottom too hot with the probe in the middle of the mash. The only way to correct it would be to get all of the grain off the bottom with a lifted 15" false bottom (like those from Jaybird) but I would still have to manually control the fire. Since I can manage good flow with a higher water to grain ratio and didn't like having to babysit it; I decided that an automatic RIMS system was a better solution for me.

The PID controller does a good job keeping the temperature steady on the RIMS tube.
The feedback probe is installed on the top of the RIMS tube so wort exiting the tube leaves at the set temperature.
When I am at the end of a brew day I simply rinse it by circulating hot water and PBW through it. Used to take the element out and inspect it, it does pick up a little sediment but not enough to have to inspect it after every brew.
My cost was close to $200. Upgrading the False bottom would have cost 1/2 as much but would lack automatic control.

 

[gifty74]

Yeah, with that link to an all stainless RIMS tube, all you need is the probe/controller, a relay contact, some QDs, and a cheap 120 VDC element, right?

 

[gifty74]

I have the controller (Auber PID with RTD sensor), so that's half the battle.

 

[mredge73]

Yeah, with that link to an all stainless RIMS tube, all you need is the probe/controller, a relay contact, some QDs, and a cheap 120 VDC element, right?

If you plan to go that route:
Best to go with a pid with a SSR control instead of a plain relay contact since it will be switching the element often.
Don't go cheap on the element. Look for a ULWD element that will fit the tube. I think mine was about $30 shipped.
Don't forget about the work box, range from $8-$30

 

[gifty74]

Ok, I got this controller http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=237.

I was thinking this would be best for the original plan of a direct fired setup where the controller has a built in SSR output. But, in looking at the other models, this one has built in SSR control output. This shows that it can run a heater that draws less than 10 AMP whereas the one I got said less than a 2 AMP heater (at 120VDC). So maybe I got the wrong one? Would the 2352 be able to run a 120V element without an external SSR? Kind of second guessing now that I might have bought the wrong one.

 

[mredge73]

You would need an external SSR with a 120VAC input trigger to rig your unit to work for a heating element.


So what was your original plan, did you plan to direct fire it with a gas gate valve with pilot?
You can still give it a try if you already bought the equipment; but just install a needle valve inline and start with a very low flame. Take your feed back at the inlet of the pump in this case.