Constant recirculation in mash vs other

[augiedoggy]

I finally installed a whirlpool arm in my 2 Kettle-Rims system and that helps the boil/Rims kettle temps stay more consistent. I have noticed that my kettle is 3-4 degree's warmer than what's returning to the mash tun and I'm chalking that up as heat loss between the hoses, pump and 65-68 degree basement.

Thats actually because your recirculation flow through the herms is too HIGH for the wort to fully equalize with the HLT temps... try slowing the flow down and the heat exchange will become more efficient as the wort has more contact time in the HLT on each pass to stabilize. The alternative is going with a longer or narrower herms coil but slower flow has the benefit of less channeling and less possible stuck flow issues from less compacting.

 

[Genuine]

Thats actually because your recirculation flow through the herms is too HIGH for the wort to fully equalize with the HLT temps... try slowing the flow down and the heat exchange will become more efficient as the wort has more contact time in the HLT on each pass to stabilize. The alternative is going with a longer or narrower herms coil but slower flow has the benefit of less channeling and less possible stuck flow issues from less compacting.

What if my set up isn't a traditional HERMS? It's more like the BrewEasy where the mash gravity drains to the kettle which contains the heating element. I set up the whirl pool so that the wort returning would keep the liquid moving and temp steadier. To keep the level in the kettle at the right flow rate, I usually have to turn my pump down quite a bit so that it doesn't get too low or too high of a level.

 

[augiedoggy]

What if my set up isn't a traditional HERMS? It's more like the BrewEasy where the mash gravity drains to the kettle which contains the heating element. I set up the whirl pool so that the wort returning would keep the liquid moving and temp steadier. To keep the level in the kettle at the right flow rate, I usually have to turn my pump down quite a bit so that it doesn't get too low or too high of a level.

I see, I misunderstood because of the mention of herms above..I see you mention a form of rims. 2 degrees is more the norm and depending on the time of year I have seen that in my rims system since my system is mounted in front of a window.
But if your hoses are long enough or its cold enough in the room that or the temp sensors not being in sinc could account for it.
Are you measuring the wort leaving the rims kettle at a tee or inline somehow where its actually leaving the kettle? thats the only place that matters since due to the placement of the probe in the kettle vs the location of the element the temps would vary depending on where you measure at pretty much any temp except boiling. even with mixing the water depending on how effectively its done and the density of the element around this would still happen to a degree

 

[Blazinlow86]

Thats the opposite of what physics would dictate.. Think about it. If it ever caught up it would take many inefficient recirculation passes at higher flow and it likely would lag behind HLT temps for most of the mash.
The reported norm in average room temp area is a 1-2 degree temp differential due to heat loss from the mash tun and hose walls (depends on hose length too) but I suspect that would vary for some due to time of year.

I think we're talking about two different things. I was talking about the input and output temps of the mash. On my first few brews with the Herms system I was running too tight of crush and getting poor flow rate which made the mash temp lower coming out than what was coming in from the Herms. Once I got the grist sorted out and able to pump full speed it matched as intended. My mash tun is a stainless pot without insulation and I do 18g batches so generally 35+ pounds of grain. Maybe on smaller setups with less liquid to keep at temp it wouldn't require the same. Definitely not a engineer but it seems to make sense in my head. The more liquid in the mash tun the less times it will pass thru the herms if the flow rate was the same? Cheers

 

[augiedoggy]

I think we're talking about two different things. I was talking about the input and output temps of the mash. On my first few brews with the Herms system I was running too tight of crush and getting poor flow rate which made the mash temp lower coming out than what was coming in from the Herms. Once I got the grist sorted out and able to pump full speed it matched as intended. My mash tun is a stainless pot without insulation and I do 18g batches so generally 35+ pounds of grain. Maybe on smaller setups with less liquid to keep at temp it wouldn't require the same. Definitely not a engineer but it seems to make sense in my head. The more liquid in the mash tun the less times it will pass thru the herms if the flow rate was the same? Cheers

Maybe we are not talking about the same thing. I still dont know how you had so much temp loss from what was coming out vs coming in when things stabilized after the first 5-10 mins.

Im just saying if the flow rate of the wort through the rim or herms is too fast or the herms coil is too short (creating the same shorter exposure to the correct temps) the equilibrium cant be reached. therefore slowing the flowrate down usually has multiple advantages. Going by the experiments and brewing Ive done over the years, in a room temp environment the mash will not drop more than a degree or so in the time it would take the wort to travel through even 35pounds of wort at as little as 2gpm flowrate. Even in an uninstalled kettle as a mashtun. I generally only brew 11 gallon brews but the larger the grist the better it is at holding temps on its own vs smaller setups.
I've gone as low as 1gpm and still had matching temps within a degree from the outlet of my MT and outlet of my rims. that said as stated above things like hose length and pump placement come into play. all my lines are hard plumbed stainless (besides one short hose) which you would think would create more heat loss if anything and my pumps are installed inline which im sure has an effect.
Someone brewing with a system outdoors on a windy day or in a garage in the cold winter would have drastically different results.

 

[Blazinlow86]

Maybe we are not talking about the same thing. I still dont know how you had so much temp loss from what was coming out vs coming in when things stabilized after the first 5-10 mins.

Im just saying if the flow rate of the wort through the rim or herms is too fast or the herms coil is too short (creating the same shorter exposure to the correct temps) the equilibrium cant be reached. therefore slowing the flowrate down usually has multiple advantages. Going by the experiments and brewing Ive done over the years, in a room temp environment the mash will not drop more than a degree or so in the time it would take the wort to travel through even 35pounds of wort at as little as 2gpm flowrate. Even in an uninstalled kettle as a mashtun. I generally only brew 11 gallon brews but the larger the grist the better it is at holding temps on its own vs smaller setups.
I've gone as low as 1gpm and still had matching temps within a degree from the outlet of my MT and outlet of my rims. that said as stated above things like hose length and pump placement come into play. all my lines are hard plumbed stainless (besides one short hose) which you would think would create more heat loss if anything and my pumps are installed inline which im sure has an effect.
Someone brewing with a system outdoors on a windy day or in a garage in the cold winter would have drastically different results.

I have a 50 foot 1/2 stainless Herms coil and run my chugger pumps full speed. As long as its run at full speed the temps match everywere. There is zero offset required anywhere. I just set the hlt to the mash temp I want and it comes out of the MLT at that temp. Admittedly I haven't really tested this all that much as after the 2nd brew on the system I got it dialed in and able to run the pumps full speed and have appx 50 batches thru the system now and always hits the numbers spot on. I'll give a exaggerated scenario as why I thimk the low flow situation causes temp stratification. Say you had two setups exactly the same. Only difference is one mlt had 5 gallons in it and the other had 50 gallons in it. If your flow rate was 10 gallons per hour the 5 gallon batch would completely turn over the liquid two times in the hour mash compared to the 50 gallon batch whick would only turn over 20%. Again I'm no scientists and this could be completely incorrect. I can tell you that when my systems flow was poor the temp consistancy was as well. Cheers

 

[augiedoggy]

I have a 50 foot 1/2 stainless Herms coil and run my chugger pumps full speed. As long as its run at full speed the temps match everywere. There is zero offset required anywhere. I just set the hlt to the mash temp I want and it comes out of the MLT at that temp. Admittedly I haven't really tested this all that much as after the 2nd brew on the system I got it dialed in and able to run the pumps full speed and have appx 50 batches thru the system now and always hits the numbers spot on. I'll give a exaggerated scenario as why I thimk the low flow situation causes temp stratification. Say you had two setups exactly the same. Only difference is one mlt had 5 gallons in it and the other had 50 gallons in it. If your flow rate was 10 gallons per hour the 5 gallon batch would completely turn over the liquid two times in the hour mash compared to the 50 gallon batch whick would only turn over 20%. Again I'm no scientists and this could be completely incorrect. I can tell you that when my systems flow was poor the temp consistancy was as well. Cheers

As you stated your example is extremely exaggerated to be an actual factor of concern (who is going to pump at .16gpm?).

But I understand your point and its one I had to think about when deciding to use 24v dc 7gpm pwm speed controlled pumps on my 3bbl brewing setup for rims flow and sparging. I intend to recirculate at a low speed of around 5gpm and that means I will only "reheat" the mash about 4 times on a 1 hour mash cycle if I remember correctly which is actually plenty since when talking with a lot of people using the same 3bbl mash tun on pro brewer many state they dont even need to use a rims or herms to do a good job of maintaining mash temp with such a large mass.
I have done water tests with this setup and its performed very well at ramping and maintaining temps of about 80-90 gallons of water. I do have the output of my rims very close to the input of my MT with only a 12-15" hose between the two which minimizes the temp loss many compensate for by setting the HLT or Rims at a degree or two higher for. (stouts rims design mount directly to the side of the mash tun to address this factor.)

Again the main point im getting at is I'm not sure why you would be having issues maintaining a steady mash temp at any flow speed other than full blast.. It really should do a more stable job if anything at slower speeds along with the benefit of more consistent flow speed and no channeling for better efficiency and a more even grain bed which means clearer wort and less grain finding its way through your FB and into the pumps and BK. Especially for you since your mash volume is larger. Thats all im trying to point out. what your doing is working for you and im not trying to tell you otherwise but on the point your trying to make for others that higher flow results in better temp control I just dont see the same results in my experience. if x amount of time is enough to heat to x temp in one pass at Y speed then it will do just as good a job at a lower speed not the the way around unless there was considerable cooling going on in some long hoses from one vessel to the other that the faster speed helped minimize but it would have to be a lot for 4-5 degrees loss.

 

[postalbunny]

I have a 50 foot 1/2 stainless Herms coil and run my chugger pumps full speed. As long as its run at full speed the temps match everywere. There is zero offset required anywhere. I just set the hlt to the mash temp I want and it comes out of the MLT at that temp. Admittedly I haven't really tested this all that much as after the 2nd brew on the system I got it dialed in and able to run the pumps full speed and have appx 50 batches thru the system now and always hits the numbers spot on. I'll give a exaggerated scenario as why I thimk the low flow situation causes temp stratification. Say you had two setups exactly the same. Only difference is one mlt had 5 gallons in it and the other had 50 gallons in it. If your flow rate was 10 gallons per hour the 5 gallon batch would completely turn over the liquid two times in the hour mash compared to the 50 gallon batch whick would only turn over 20%. Again I'm no scientists and this could be completely incorrect. I can tell you that when my systems flow was poor the temp consistancy was as well. Cheers

I think we may be confusing where your probes are, what temps you're getting, and at what speeds.

Your liquid leaving the herms coil should match the HLT/herms temp exactly... regardless of speed, unless you're pumping too fast (my 50ft coil even at full speed has no issues). You should never see a lower egress temp out the HLT coil than the actual HLT water. If you notice a lower temp than your HLT water and you have a 50ft coil then investigate this... most likely therm calibration issues. Make a crushed ice water bath in a cup and see what each therm says the temp is, then adj calibrations

Your mash tun temp should match within a few degree's of the HLT/herms coil... all things perfect, it'd match 1:1 but we lose heat due to the thin walls of the kettle and the hoses/valves. Not much, but usually about 1-2 degrees over some minutes. I notice i need to set up to 4degF diff when doing 5gal batches to maintain mash temp, and about 1-2degF when doing 10 gal batches in my 20gal kettles. The extra grain helps hold the heat in. If i wrap a blanket around my MLT I notice less drop... down to 2degF on a 5gal batch.

My settings:
-I set my flow rate at about half speed, and measure mash temp at the output of the mash tun and with a manual thermometer in the middle of the mash. I dont' go full bore because i don't want to risk compacting the mash bed too much,i use a very fine crush and get over 85% mash eff that way.
-I masure HLT temp with a probe in the middle of the HLT while recirculating the water. This is what the PID uses for HLT.
-I measure liquid temp exiting the coil with a "t" and a electric thermometer, just for reference initially while dialing in the numbers
-I measure the mash temp with a "t" on the output valve of the MLT, and compare this to an analog therm that goes into the middle of the mash, and also using a thermopen into the middle of the mash sometimes for my own sanity.

The temp of the egress liquid out the HLT/herms/coil always matches the HLT temp, the temp of the egress liquid out of the mash tun always matches the mash temp. The only exceptions are during ramping up/down of temp (mash out to 168, my HLT reads 168 and egress water 168 but mash temp takes 10 mins to catch up). If either of these is not true you should investigate what you've got that's different, and if it matters in your setup or not. Sometimes it doesn't matter, you just do it different and as long as the beer is good and the results are repeatable it's fine.

With our particular herms setups we are adding heat from the coil/herms/hlt to account for temp lost during mash through the thin walls of the mlt. If we were not losing any temp, then we could stop recirculating and just wait until mash is done and recirc for a few minutes to clear the wort out. I was tempted to get the ss brewtech insulated tun but it cost more... and the main feature of the herms system is dealing with heat loss by recirculating and heating.

 

[Blazinlow86]

I think we may be confusing where your probes are, what temps you're getting, and at what speeds.

Your liquid leaving the herms coil should match the HLT/herms temp exactly... regardless of speed, unless you're pumping too fast (my 50ft coil even at full speed has no issues). You should never see a lower egress temp out the HLT coil than the actual HLT water. If you notice a lower temp than your HLT water and you have a 50ft coil then investigate this... most likely therm calibration issues. Make a crushed ice water bath in a cup and see what each therm says the temp is, then adj calibrations

Your mash tun temp should match within a few degree's of the HLT/herms coil... all things perfect, it'd match 1:1 but we lose heat due to the thin walls of the kettle and the hoses/valves. Not much, but usually about 1-2 degrees over some minutes. I notice i need to set up to 4degF diff when doing 5gal batches to maintain mash temp, and about 1-2degF when doing 10 gal batches in my 20gal kettles. The extra grain helps hold the heat in. If i wrap a blanket around my MLT I notice less drop... down to 2degF on a 5gal batch.

My settings:
-I set my flow rate at about half speed, and measure mash temp at the output of the mash tun and with a manual thermometer in the middle of the mash. I dont' go full bore because i don't want to risk compacting the mash bed too much,i use a very fine crush and get over 85% mash eff that way.
-I masure HLT temp with a probe in the middle of the HLT while recirculating the water. This is what the PID uses for HLT.
-I measure liquid temp exiting the coil with a "t" and a electric thermometer, just for reference initially while dialing in the numbers
-I measure the mash temp with a "t" on the output valve of the MLT, and compare this to an analog therm that goes into the middle of the mash, and also using a thermopen into the middle of the mash sometimes for my own sanity.

The temp of the egress liquid out the HLT/herms/coil always matches the HLT temp, the temp of the egress liquid out of the mash tun always matches the mash temp. The only exceptions are during ramping up/down of temp (mash out to 168, my HLT reads 168 and egress water 168 but mash temp takes 10 mins to catch up). If either of these is not true you should investigate what you've got that's different, and if it matters in your setup or not. Sometimes it doesn't matter, you just do it different and as long as the beer is good and the results are repeatable it's fine.

With our particular herms setups we are adding heat from the coil/herms/hlt to account for temp lost during mash through the thin walls of the mlt. If we were not losing any temp, then we could stop recirculating and just wait until mash is done and recirc for a few minutes to clear the wort out. I was tempted to get the ss brewtech insulated tun but it cost more... and the main feature of the herms system is dealing with heat loss by recirculating and heating.

I think I may be being confused with the original posters temp looses. If I run at slower speeds than full I needed a offset of 2 degrees. If pumping at full speed I don't need one. That's it. Doesn't make a big difference but I figured I built the herms for this specific reason so not having it 100% consistent annoyed me. That being said some people don't recirculate at all and still make great beer.. cheers

 

[Blazinlow86]

Sorry I'm terrible at using my words typing on the phone. Inassure you sure you I speak perfect English in person lol. and just for clarification the 2 degree offset I'm talking about is coming OUT of the MLT compared to OUT the herms coil. Never had any issues regarding speed getting the herms out to match the hlt temp. Cheers

 

[postalbunny]

Sorry I'm terrible at using my words typing on the phone. Inassure you sure you I speak perfect English in person lol. and just for clarification the 2 degree offset I'm talking about is coming OUT of the MLT compared to OUT the herms coil. Never had any issues regarding speed getting the herms out to match the hlt temp. Cheers

NP, that makes more sense to me then. Pumping faster also means you are turning over the liquid in the MLT faster and won't need as large of a delta to keep a steady mash temp. I just wanted to make sure you were not having issues with temps coming out the herms as that would be a totally diff issue.

The only other way to get rid of the delta is to insulate the tun to lower the heat loss. Prob cheaper/easier to just figure out what your delta needs to be to maintain the temp. It should be the same depending on mash size and pump speed.