Part of the reason I struggle dialing in mash temp (BIAB)

[mongoose33]

I'm using the Blichmann Hellfire burner as my heat source. It's a....well, hellfire. I've struggled to dial in my mash temperatures and I know why.

The pic below shows the supports for the kettle on my hellfire. Yes, what you see is glowing red hot. That's a pretty good indication of how hot the whole unit is, and it keeps pumping heat into the kettle even after I turn off the gas.

I've learned to turn it off, stir, wait a couple minutes, stir again, and it seems to work better that way. Anyone who's struggling to hit their temps, look for a source of residual heat like this one.

 

[xjedifishx]

Yeah that's throwing some heat for sure! What is that piece that's glowing?

 

[mongoose33]

Yeah that's throwing some heat for sure! What is that piece that's glowing?

It's the bottom of the kettle bar. You can see it more clearly (thought not as red hot ) in this pic:

 

[PsychoBiter]

We start ramping down the propane as it gets 5 or so degrees before we get to strike temp. That seems to help, but we have an older style Blichmann. Our supports do glow was well when cranked up.

 

[Morrey]

The good thing about the heat retention of a Hellfire, is that it can actually be an aide once you get a handle on the impact residual heat offers. I dough in and wrap, then 30 minutes later when I do a mid-mash stir, my temps are still right on the money. The residual heat from this beefy burner keeps the mash stable for sure. Even when all said and done, boil kettle washed out and all gear stowed away, the burner on the Hellfire is still almost too warm to handle. We are talking serious quality here.

 

[RM-MN]

The good thing about the heat retention of a Hellfire, is that it can actually be an aide once you get a handle on the impact residual heat offers. I dough in and wrap, then 30 minutes later when I do a mid-mash stir, my temps are still right on the money. The residual heat from this beefy burner keeps the mash stable for sure. Even when all said and done, boil kettle washed out and all gear stowed away, the burner on the Hellfire is still almost too warm to handle. We are talking serious quality here.

Have you ever taken the specific gravity right after your mid-mash stir and compared it to what you have at the end of the mash?

 

[Morrey]

Have you ever taken the specific gravity right after your mid-mash stir and compared it to what you have at the end of the mash?

I have, yes. If I do a BIAB using a press plate to press/squeeze sparge (only) in an Arbor Fab mesh basket, I may have for example 1.035 at mid mash and 1.038 when I press and recheck at the end of mash. I am only losing .5G absorption with a 10# grain bill if this factors in.

 

[madscientist451]

Yeah, I got tired of mash temperature swings and gave up, bought a round cooler and put my BIAB bag in that. Works great.

 

[RM-MN]

I have, yes. If I do a BIAB using a press plate to press/squeeze sparge (only) in an Arbor Fab mesh basket, I may have for example 1.035 at mid mash and 1.038 when I press and recheck at the end of mash. I am only losing .5G absorption with a 10# grain bill if this factors in.

Try a 30 minute mash sometime with the same squeeze and see what you get. You may be surprised. Don't go shorter than 30 minutes unless you are willing to suffer the consequences. (the consequences I get if I do a 20 minute mash instead of 60 is that I have an extra 40 minutes to do something else) Conversion happens faster than most people believe but it still takes time to extract flavors.

 

[doug293cz]

I have, yes. If I do a BIAB using a press plate to press/squeeze sparge (only) in an Arbor Fab mesh basket, I may have for example 1.035 at mid mash and 1.038 when I press and recheck at the end of mash. I am only losing .5G absorption with a 10# grain bill if this factors in.

Try a 30 minute mash sometime with the same squeeze and see what you get. You may be surprised. Don't go shorter than 30 minutes unless you are willing to suffer the consequences. (the consequences I get if I do a 20 minute mash instead of 60 is that I have an extra 40 minutes to do something else) Conversion happens faster than most people believe but it still takes time to extract flavors.

Based on Morrey's example numbers, assuming a 60 min mash, at 30 minutes you only have about 92% of the conversion that you have after an hour. An additional 8% conversion efficiency is significant.

Brew on

 

[mongoose33]

I brewed on Sunday, took my normal 15 minute sample to check pH. I also checked gravity since I had a sample, and after 15 minutes I had 1.038. The gravity pre-boil, after an hour, was 1.0495.

Sadly for this example, I also unwrapped the kettle and stirred at 30 minutes, but for reasons probably related to A) having a friend over watching me brew, and B) doing a little quality control testing on an earlier batch, I didn't think to take a gravity reading at 30 minutes.

I may brew again this weekend, if I do I'll try to remember to take gravity readings at 15 and 30 minutes.

I'm crushing at .020, and so it's hard to imagine there's a lot else going on after 30 minutes. I'll have to check and see. I'll report back here, naturally.

 

[Morrey]

Based on Morrey's example numbers, assuming a 60 min mash, at 30 minutes you only have about 92% of the conversion that you have after an hour. An additional 8% conversion efficiency is significant.

Brew on

Doug, adding to this point, the increase of .003 during the additional 30 minutes is based solely on pressing with a specifically designed plate to extract wort from the grain bed. I started pressing, roughing up the grain bed, then pouring 1/2 gallon of warm water over the grains and pressing again. I can get another .002 out of the wort from this sparge, and if I concentrated back out that 1/2G of water, it should be a shade more than .002 gain. This is all done in a mesh basket, so its a bit easier to deal with than squeezing.

 

[doug293cz]

Doug, adding to this point, the increase of .003 during the additional 30 minutes is based solely on pressing with a specifically designed plate to extract wort from the grain bed. I started pressing, roughing up the grain bed, then pouring 1/2 gallon of warm water over the grains and pressing again. I can get another .002 out of the wort from this sparge, and if I concentrated back out that 1/2G of water, it should be a shade more than .002 gain. This is all done in a mesh basket, so its a bit easier to deal with than squeezing.

If the conversion is complete, and the mash sufficiently stirred prior to run-off, then pressing will not provide any wort with increased SG. Sufficient stirring is defined as having eliminated any concentration gradients between the bulk wort and wort adsorbed/absorbed by the grain. In cases of insufficient stirring, then the wort adsorbed/absorbed by the grain can have a higher SG than the bulk wort, and in this case, the pressed wort would have a higher SG than the bulk wort. The other possibility is that conversion wasn't complete at the time of initial run-off. Then by the time you press, conversion has continued, thus raising the SG of the wort that will eventually be pressed.

Brew on

 

[mongoose33]

I said above I'd report on a 15- and 30- minute gravity as compared to OG.

My next batch was a Cal Common. I had a gravity of 1.044 at 15 minutes, 1.044 at 30 minutes. Preboil gravity was 1.046. So at 30 minutes, virtually all the conversion was done.

I squeeze, but no sparging. There's not a lot of wort remaining in the spent grain, maybe 3/4 gallon or a shade more. I start w/ 7.25 gallons.

 

[RM-MN]

I said above I'd report on a 15- and 30- minute gravity as compared to OG.

My next batch was a Cal Common. I had a gravity of 1.044 at 15 minutes, 1.044 at 30 minutes. Preboil gravity was 1.046. So at 30 minutes, virtually all the conversion was done.

I squeeze, but no sparging. There's not a lot of wort remaining in the spent grain, maybe 3/4 gallon or a shade more. I start w/ 7.25 gallons.

It looks to me like virtually all the conversion was done at 15 minutes. That doesn't surprise me. Had you sampled at 10 minutes you may have had the same results.

I've used my refractometer to sample the wort at 30 minutes and found it to be lower than expected, stirred and quickly sampled to find the results much higher. Your preboil gravity, being only .002 higher than your 30 minute sample, may have been due to stratification and insufficient mixing rather than continued conversion.

If you don't mind, take a sample at 5 and 10 minutes too on the next batch and see where your numbers come out, making sure to stir before sampling.

 

[mongoose33]

It looks to me like virtually all the conversion was done at 15 minutes. That doesn't surprise me. Had you sampled at 10 minutes you may have had the same results.

I've used my refractometer to sample the wort at 30 minutes and found it to be lower than expected, stirred and quickly sampled to find the results much higher. Your preboil gravity, being only .002 higher than your 30 minute sample, may have been due to stratification and insufficient mixing rather than continued conversion.

If you don't mind, take a sample at 5 and 10 minutes too on the next batch and see where your numbers come out, making sure to stir before sampling.

I always stir very well before I take a sample. Not sure I want to take samples at 5, 10, 15, and 30. Hard enough to keep the temps stable.

And FWIW, the reason I am focused on 30 minutes as a minimum, and why I said it above, was in response to your feeling that a too-short mash will not extract all the flavors. Makes sense to me, and doesn't hurt to go a little longer.

 

[RM-MN]

I wouldn't advocate the samples at 5, 10, 15, and 30 for each batch. Try it once so you see where the difference lies. If you use a refractometer the sample shouldn't take long and the temperature loss is immaterial if conversion is done. I'll agree that you shouldn't stop the mash before 30 minutes unless you are daring and want to see where the flavor extraction is done. Hint: my experiments say it doesn't take 30 minutes but 30 is a safer number.

 

[mongoose33]

I wouldn't advocate the samples at 5, 10, 15, and 30 for each batch. Try it once so you see where the difference lies. If you use a refractometer the sample shouldn't take long and the temperature loss is immaterial if conversion is done. I'll agree that you shouldn't stop the mash before 30 minutes unless you are daring and want to see where the flavor extraction is done. Hint: my experiments say it doesn't take 30 minutes but 30 is a safer number.

I have to be honest--I'm not all that interested in researching this. I wrap up my kettle/burner combination in a large quilt-like thing to keep heat in. Kind of a pain to do and undo. I doubt it matters much after 30 minutes or so, but early on, I'm even hinky about stirring at 15 minutes. I think that's necessary which is why I do it, but I'll have to stir at 5 minutes, 10 minutes, and that will result in loss of temperature.

I think 30 is a fine number, and I'm not all that concerned about shortening it. I might at some point diddle around with that, but for now, I'm more than happy to keep mashing at a 30 minutes to an hour.

 

[MaxStout]

I get a lag effect with upward temps too, but not so pronounced, likely due to my thin kettle. Not a lot of thermal mass to keep feeding heat inward. After I shut off the propane, the strike water will creep up about a degree, maybe 1.5 by the time it reaches equilibrium. So, if I'm shooting for 150, I kill the heat at about 146-147, stirring all along. See what it creeps up to and if I need it higher, run the gas for a short time, rinse and repeat. Incremental and kind of tedious, but that's what I have to do.

After mash in, I cover with an old blanket. That thin kettle is also good at losing heat outward. But even on a cold day in the garage (say, 30s), the mash will only drop about 1 degree in 20 minutes. If it drops too low, I can run the gas for a moment and stir, check temp, etc.