BRUTUS Mash Temps

[pearlbeer]

I have a BRUTUS 10 systems - direct fired RIMS. I typically do 12-18G batches in a 100qt SS MLT. I have an analog thermometer in the kettle and my PID is mounted on a T on the out flow of the kettle.

Typically, while mashing, I see a 5-7deg variance between the liquid (outflow) and the mash temp (kettle) with the out always being hotter.

Anyone else experience this? Should I just worry about the outflow of the wort, or adjust to get the entire mash up to temp.

Before you ask - yes my thermometers are calibrated...and I have double checked the measurements with a digital handheld.

 

[ehedge20]

This is typical, you need to be concerned with the mash temp and not the liquid. Adjust your digital temp up or down to get your analog thermometer in your mash to your desired temp.

 

[drkwoods]

Last year I had this same question during my build and I even ran some experimentation. Here's my graph I made
https://www.homebrewtalk.com/f11/herms-temp-measuring-questions-210195/

 

[cwi]

This is typical, you need to be concerned with the mash temp and not the liquid. Adjust your digital temp up or down to get your analog thermometer in your mash to your desired temp.

The liquid portion of the mash is not just a fluid whose sole purpose is to heat the grain in the tun, it is also a significant portion of the 'mash'. You have to consider the 'mash' as a whole. That is why nobody with any sense uses a probe in the grain bed as the input to the temp controller for a RIMS tube or HERMS heat source. This is a direct fired RIMS MLT which is even more problematic from a temperature gradient and differential perspective.

That said, even for a steady state mash profile, there will always need to be some temp differential between post-RIMS/HERMS and the tun as long as there is heat loss in the tun and system, which there always will be. However, there is a limit to the amount of heat that can be infused into the fluid to counteract the heat losses. The magnitude of the differential is a personal choice based on your beliefs regarding mashing science, enzyme denaturing, etc., but there is a limit. A 7F diff is on the high end of that range, even for a HERMS or RIMS tube, unless your mash temp tolerance is > 5F.

The situation at hand is even more complex because it is a direct fired MLT RIMS instead of a more gentle HERMS or even PID controlled ULWD RIMS tube. With a direct fired MLT, there will be a layer of higher temps close to the heated kettle surface. There is also no easy way to get a temp reading close to the pre-RIMS side of the mash to know what the mash exit temp really is. Additionally, and this is the most important part, the tun temp is coming from a slow reacting complete POS analog dial thermo that only probes in a few inches into an isolated pocket of the grain bed very close to the tun wall which is the biggest heat sink in the whole system and gets more or less exposure to the recirc flow-through depending on where the single-downward-pointing-hose-barb-in-the-lid based sparge arm (jet?) is currently boring a vertical hole in the grain bed.

Insulating the tun would help significantly, but it is direct fired so it is problematic to find a flame proof way of insulating it.

Have you considered going to a HERMS?
Only this time try one that isn't based on your wife's $10 digital turkey thermometer that reads 40F low; is only noticed 40 minutes into the mash when it quits completely; and results in an IPA that looks like a pint of the water after the 'chefs' at Golden Corral finish cooking up the day's trough of pasta. And no, I didn't just make that up.

 

[audger]

cwi covered most of what i had to say!

also just remember that the temperature differential between mash temp and HEX exit temp will be reduced by a faster flow rate. however if the flow rate is too fast, you will compact the grain bed, so you have to find a happy medium.

 

[cwi]

cwi covered most of what i had to say!

also just remember that the temperature differential between mash temp and HEX exit temp will be reduced by a faster flow rate. however if the flow rate is too fast, you will compact the grain bed, so you have to find a happy medium.

No true HEX here, only direct flame to the bottom of the tun; but yes, more flow allows less of a diff to counteract tun losses or to step. The mash already stuck a few times at the rate we had it, and the bed was rock hard at the bottom before stirs. That, and more flow would have just meant a bore hole all the way to China, instead of just half-way. Did someone mention 'sparge arm'?

 

[ehedge20]

On the Brutus the temp probe is not in the mash but in the liquid out line. The liquid is heated up and recirculated into the mash where the heat is dispersed rather quickly as my digital and analog thermometers do not take but a few seconds to give the same reading. A thinner mash will also make this happen more efficiently. At first my temps differed around 7 deg until I inserted a 1.5" copper tube tube in the middle of the mash with drilled holes to run my hot wart into thus distributing the heat fast and even throughout the grain bed. No stuck sparges for me. Also I have a 6" probe on my analog which reached the middle of the bed.

 

[cwi]

On the Brutus the temp probe is not in the mash but in the liquid out line.

That is the whole point, and something Lonnie is very specific about. He sets the post-RIMS mash temp at the highest he wants to mash, and lets the grain bed temp play catch up. If there is a large differential between that and a secondary temp probe in the grain bed, you can't just arbitrarily up the post-RIMS temp without adversely affecting the mash liquid that is being heated. This is the same mash liquid where the business happens, and is no different than if the liquid in the center of your grain bed went overtemp. It is for a fairly short period of time, until it mixes back in the main mash, but can be cumulatively significant. Especially with a direct fired RIMS where the entire bottom of the tun is being heated, but only being pulled from one spot.

If there is a large differential between the RIMS output and the center of the bed temps, other things need to be done than just raising the output temp, although a 1-2F increase probably won't have any major adverse effects. That temp differential, and even larger ones, are more acceptable in a HERMS or ULWD RIMS tube where the heating is more even and flow is more controlled. HERMS and RIMS tubes also have the advantage of providing a location to place a monitoring temp probe pre-RIMS heat source to get a more accurate reading of mash temps.

At first my temps differed around 7 deg until I inserted a 1.5" copper tube tube in the middle of the mash with drilled holes to run my hot wart into thus distributing the heat fast and even throughout the grain bed. No stuck sparges for me. Also I have a 6" probe on my analog which reached the middle of the bed.

I may be misinterpreting your description, but it reads like you place the return in the middle of the grain bed, i.e. below the surface of the grain bed. I assume you distribute it above the grain bed like a sparge arm.

 

[ehedge20]

I distribute directly in to the middle of the grain bed using my copper column with holes drilled all the way up to the top. I still get all the filtering I need as the holes at the very bottom fill up with grain and the holes are large enough at the top that there is minimal pressure so the wort does not spray out like a jet. It creates a gentle recirculation throughout the whole batch and I have measured even temps from the bottom to the top.

I have been achieving almost 80% efficiency every time as well.

 

[cwi]

Your mid-mash vertical column sparge arm goes against prevailing fly sparge and RIMS theory, but I am sure it works good enough. Most of the flow is probably coming out the top/surface holes anyway since there is no back pressure from liquid or grain blocking the holes.

 

[ehedge20]

I take out the column before using my fly sparge. The column is only there while I recirculate when mashing to keep the temps even.

 

[cwi]

I take out the column before using my fly sparge. The column is only there while I recirculate when mashing to keep the temps even.

The principle, and desired effect, is the same whether during the mash or sparge. The fluid seeks the path of least resistance, and the goal is to have flow throughout the bed. You may have either planned for this with hole distribution and size, or gotten lucky, if you have any significant flow out of the column at depth. There would need to be enough flow to create back pressure at the upper holes that have lower restriction, and therefore pressurize the column; or enough downward velocity of the input stream to cause similar pressure effects. This will cause some flow to be forced out the lower holes where flow is restricted by hydrostatic pressure (which increases as depth increases) and by grain blocking the exit path.

The holes could be strategically increased in size as depth increased to counteract the hydrostatic effects, but the restriction by the grain would be a tricky one. Different grain bills, mash thickness, and volume would change the dynamics as well. Another tricky part is trying to get the flow from the different levels to create an even throughput.

You could do a simple test with the spent grain bed to see what is actually happening. Just stir up the grain bed; add your column back in; and add some food coloring. An autopsy of the bed after less than a minute of recirc should show what is going on.

You could make a build thread on your mash strategy to get some feedback on it.

 

[ehedge20]

My main goal was to get hot liquid into the center of the mash quickly to stabilize the temp which is working. The liquid will flow more easily out of the upper holes in the column which is pulled down by the suction of the recirculation. At least that is the theory. I will do the dye test and report my results, thanks for the input.

 

[cwi]

My main goal was to get hot liquid into the center of the mash quickly to stabilize the temp which is working. The liquid will flow more easily out of the upper holes in the column which is pulled down by the suction of the recirculation. At least that is the theory. I will do the dye test and report my results, thanks for the input.

Your approach and strategy are confusing to me. For a single step mash, the center of the mash is already the most stable temperature zone, and the area near the tun walls is the least. While performing a step, using some kind of mash injection approach makes some sense, but using the normal top down flow makes more.

If you were to post a thread detailing your mash column device and process, you might get input more specific to this technique.