Scorched grains in direct fire mash tun

[iam4]

All, I was hoping to run an idea or two up the flagpole to see whether the more experienced AG brewers could offer thoughts or advice.

I brewed a hefe using a direct fired mash tun to do a step mash. I use a Blichmann boilermaker with false bottom over a flame. Had done this several times before with no problems. I recirculate with March pumps (but pretty slowly to be honest) and try to keep the flame low. It takes a long while to hit 152 or so from my protein rest step but it had been working...until the last time. The usual thick paste like residue at the bottom of my mash tun (from the wheat) was completely scorched. Ouch.

To alleviate this next time I was intending to recirculate at full speed and still keep the flame low. I was also tempted to buy a thick aluminum disk to place under the mash tun. As I understand it aluminum is a much better heat conductor than stainless and I was hoping that heating the aluminum would more evenly distribute the heat over the bottom. The scorched area was small, by the way, just the size of the burner underneath. Does anyone have any experience with this? Is that aluminum idea smart or a waste of money? Any other ideas to avoid the scorched grain problem besides faster recirc?

I know some will tell me a protein rest isn't necessary, but I want to keep it. I do think it adds something especially to a hefeweizen.

Thanks everybody.

 

[grathan]

Insulation might be a good investment. It may require less heat on the bottom if less goes out through the sides of the pot. Also leaving the lid on.

 

[wilserbrewer]

Remove the false bottom and stir constantly while heating in a mash tun, transfer to lauter tun.


Wilserbrewer
Http://biabbags.webs.com/

 

[tootal]

We have a RIMS system and ramp temperatures with flame on our mash tun without any problems. Increase you recirculation speed and keep the flame low but not too low or it will take forever. We can usually go from 131 to 144 in 15 to 20 minutes without any issues. 144 to 158 about the same. Keeping the flow going is key, also make sure your flame is not actually touching the mash tun. Lowering it down a little will help a lot.

 

[grathan]

Which burner you got?

 

[acidrain]

Out of the 10 or so direct fired with recirc. mashes I did, I scorched two of them.
Went to an electric RIMS tube, and scorched two more out of five.
I tried stir bars and elaborate insulation and never got consistent results with either RIMS or direct fired.
Went to a HERMS, and never scorched one since.
I have to admit, I never tried a separate lauter tun, and that could have made a difference, but short on space, I'm glad I bailed and went HERMS.

 

[tootal]

Out of the 10 or so direct fired with recirc. mashes I did, I scorched two of them.
Went to an electric RIMS tube, and scorched two more out of five.
I tried stir bars and elaborate insulation and never got consistent results with either RIMS or direct fired.
Went to a HERMS, and never scorched one since.
I have to admit, I never tried a separate lauter tun, and that could have made a difference, but short on space, I'm glad I bailed and went HERMS.

I've been using a RIMS system for 8 years now. Never have scorched anything. I think folks either have too big of a burner or it's too close to the keggle. We don't insulate or stir our mash. We constantly recirculate and use a 220 volt heating element with only 110 volts going to it. We can maintain temps at + or - 1 degree.

 

[acidrain]

I've been using a RIMS system for 8 years now. Never have scorched anything. I think folks either have too big of a burner or it's too close to the keggle. We don't insulate or stir our mash. We constantly recirculate and use a 220 volt heating element with only 110 volts going to it. We can maintain temps at + or - 1 degree.

Ever get a stuck mash while recirculating? When you do, you will get a scorched batch... even with low wattage and ULWD.

And, if you've never, ever ever had a stuck mash, you aren't pushing the envelope with grain crush.

I've done them all, and my opinion, HERMS over RIMS hands down. It was even cheaper.

 

[tootal]

Nope, never had a stuck mash. If we're working with rye we use rice hulls otherwise we don't. We are 86% efficient in the fermenter and that's good enough for me. If we pushed the envelope on our milling it definitely could make the difference.

 

[dcbc]

I direct fire in one of those tri clad bottom kettles with a 20 tip jet burner underneath. False bottom is about 3" off the bottom and mash is probably thinner than most. I recirculate at what I estimate is 2--3 gallons per minute and no issues with stuck mashes or scorching. Did a rye ale last month and will be doing a hefeweizen next.

 

[tootal]

Which burner you got?

Sorry Grathan, I missed your question. Here is what we have:

https://brewmagic.com/product/high-pressure-burner-for-brew-magic-system/