Constant recirculation in mash vs other

[Zealous61]

I have a Spike HERMs system and have been very happy to date. I have developed a mash schedule that works well for me. I was surprised to see the Spike website suggests a completely different method than what I was doing and I would like some opinions on the matter.

I set my HLT maybe 5 degrees above strike temp and run both the HERMs coil pump and the HLT recirculating pump wide open until I reach strike temp in the mash tun. I then turn off the mash/HERMS pump and dough in. I then add cold filtered water to the HLT to bring it down to maybe 2 degrees above target mash temp. I then turn the pump back on. I run the pumps the entire mash.

The rec on the Spike page says to set the HLT at 180 degrees and only turn on pump every 10 minutes briefly to keep mash temp where you want it.

I know this goes back to the qestions regarding protein shear from pumps, but I have never seen a reccomendation to use a HERMs system in a fashion without constant recirculation. Does anyone else share my concern of exposure of mash to such high temps and creating large amounts of unfermentables and resultant poor attenuation?

What does everyone else do?

 

[LarMoeCur]

When I was building my system, I read plenty of post of brewers running the HLT at 180F and cycling the wort pump. I've even send or heard of HLT being set to boiling temps 200F plus. I've never ran my system that way so I cannot speak from experience only theory.

In theory, you would certainly be denaturing the enzymes at an increased rate. Now, would that affect the flavor of the beer? I think it would. If you are trying to mash at 148F for highly fermentable wort (dry finishing beer), the wort trapped in the HERMS coil between cycles would not be at 148F. Now you run the pump for 2 minutes and if the wort exiting the HLT is at 180F, it would only take a minute or two to cycle your entire mash volume through the 180F HERMS coil, which is not favoring the Beta enzymes.

To answer your question. I run my HLT 2 degrees above mash temp and recirculate continuously.

 

[hopjunkie26]

I have ran my system both ways. (constant recirc and HLT at ~180)

I couldn't tell you that I have noticed a difference in beers using one method or the other. When I switched to constant recirc several months back, I feel that I get more consistent mash temps that is for sure. That is the reason that I made the switch.

 

[Smellyglove]

I see no reason not to run the pump fulltime. There may be some reasons behind it, but I've never came across one. Filters the wort and keeps a steady temperature. But then you can't have a higher temp in the HEX than your target temperature. The Spike-thing seems a bit high and low, instead of just steady.

 

[Genuine]

I constantly recirculate during the mash to keep a constant mash temp and I seem to consistently hit my gravity predictions.

 

[Yooper]

I generally recirculate the whole time, with my HLT set at 3 degrees higher than my mash temperature. The only time I don't is if I'll be out of the brewery for some reason (like a quick run to the ER or other things that have happened) because I'm afraid of a problem while I'm gone. That's only happened a handful of times in more than 10 years though.

The reason I love my HERMS is because of the stable temperatures and clear wort. I don't see any reason to change it.

 

[kh54s10]

I don't yet have a system like that but, one of the benefits of a herms system is to make your beers more consistent. If you are allowing swings in your mash temperature by turning on and off the pump it seems like you would lose that benefit.

 

[itsnotrequired]

before filling the mlt, i set my hlt a few degrees above mash temp so the mlt is a few degrees below strike temp. after adding the grain, i set the hlt to one degree above mash temp and after a few minutes, hlt temp drops while mlt comes up to mash temp. then i let the system recirc constantly during mash. this is for convenience, as i typically take a nap during the mash. having to manually cycle the hlt pump to maintain temps seems to defeat the purpose of having pids and similar controllers.

 

[HornyGoatStout]

I have a Spike system, and I also do a constant recirc through the HERMS. I monitor temperature on the top mash tun input to make sure that it is always hitting my mash temp. That generally puts my HLT at about 2-3 degrees above mash temp.

 

[WCWMatt]

Constant recirc on my Spike system. clear wort, hitting gravity goals... No reason to change from my perspective.

 

[Blazinlow86]

I recirculate the whole time also

 

[sandyeggoxj]

I have a 1/2bbl eherms system. I heat the HLT to mash temperatures (3ºF above my desired mash to account for heat loss during recirc) and I add all my crushed grain to the MLT. I heat the strike water in the BK and then underlet that into the MLT. I usually get my strike within a degree or two which then normalizes with the recirculation through the herms coil in the HLT. I recirc for the 60 minute mash and then raise the HLT to 172 to ramp the mash to 168 for a 10 minute mashout. I've been brewing this way for 3 years on this equipment and have no plans to change.

 

[Fibonacci_01123581321]

I recirculate during the entire mash. My biggest concern of intermittent recirculation through a hotter than necessary HLT coil would be denaturing enzymes as mentioned previously.

 

[augiedoggy]

I use a rims but I recirculate the entire time on my setup using a super ULWD cartridge heater to not denature enzymes... I average 90% efficiency this way with only 1.5-2gpm max flowrate..
Does the spike setup have a way to keep the liquid in the hlt stirred and consistent? if not it may be why they suggest doing it the way they do.
I did not have consistent results with my herms system until I used a pump to keep the hlt water moving.

 

[Zealous61]

Yes, the other pump is used to constantly recurculate the HLT water.

 

[ryanj]

This is just another example that there's no one right way to mash. I personally recirculate constantly throughout my entire mash process and it works well for me (now that I got my system dialed in), but I also built my panel/controls with the assumption that I'll be constantly circulating.

It seems weird that Spike gave those directions to only recirculate occasionally especially when on their demo video, they instruct otherwise (to constantly recirculate throughout the whole mash). I say stick what works for you.

 

[postalbunny]

One thing about using 180°F int he HLT is that the wort is being heated to that temp by the time it leaves your coil... when i first started I was worried about why I had to keep my HLT at 156 to get a 152 mash temp so I stuck probes on the HLT exit, MLT entrance, and MLT exit to see...

what I found is:

1) temp leaving the kettle matched the mash temp (manual probe on kettle sticking into grain bed)
2) temp leaving HLT matches the HLT water
3) temp entering MLT doesn't lose any more than 0.5°F, usually matches 1:1 what the HLT was. This is where I was worried i was losing temp

My thought is that since i have single-wall MLT that i'm losing 2-3°F due to ambient air. If i were to wrap some insulation around the MLT I bet the temp diff would go to 0. But that seems like a hassle and the RIMs part of this setup takes care of it. Plus, i make a mess when i clean these kettles, splashing water everywhere... if i wanted an insulated tun i'd have sprung for the SS-brewtech one.

The reason I posted this info is because of #2 above... the temp leaving your HLT coil matches the HLT water. If you set that temp to 180 then the wort will be at 180 for a short period of time while it travels through the coil and returns to the MLT to normalize. Anything over 168 and your denaturing enzymes. I don't know how fast denaturing happens, but i can guarantee you'll have a different beer than someone who mashed in a cooler and kept stable temps.

Beer will be fine, but i suspect you'll have a beer more similar to a step-mash of say 152-160 due to the variations of temp. Worst case you actually denature the enzymes and they don't convert...

 

[augiedoggy]

I agree with above... I do not use an insulated mash tun.. That is why I have and use a rims. The wort in my rims is only heated to the temp I desire (or damn close) however this is not the case in many rims designs and I believe one reason they get a bad rap.
Heating the HLT for a herms to 180 to get the temp average you want would be more like using a traditional rims IMO and should not need to be done unless something is wrong with the design implementation.
In many rims designs you have an element that may have a higher watt density which actually heats SOME of the wort passing through that comes in contact with the surface as it passed over to a much higher temps and that wort mixes with other wort that did not come in direct contact with the element as it mixes and passes through the rims where the temp probe at the opposite end just sees the temp of this somewhat mixed average...
I wouldnt doubt this could cause denatured enzymes... A herms on the other hand heats more evenly and gently not unlike the steam often used by larger pro breweries.

I designed my rims with the longest, lowest watt density cartridge elements I could in both my home and brewpub setup and made my rim tubes very long vs the off the shelf offset T type this appears to accomplish a couple things better,

Longer more consistent contact time on each pass and gentler heating not unlike the herms , but with the ramping capability and adjustability of a rims as well. This is why I can step mash and raise my 11 gallon mashes almost 3 degree per minute with just 1800w of power drawing under 8 amps off my 30a main power feed. I believe my rims act more like real heat exchangers than most which dramatically fluctuate in performance and consistency depending on flow rate..

I'll ask this question though... Why were /are the Germans so successful with Decoction mashing? shouldnt it cause massive amounts of denatured enzymes?

 

[mabrungard]

As long as the wort isn't heated above your target mash temperature, there isn't a chance of denaturing enzymes. To avoid overheating wort, the temperature sensor needs to be located immediately downstream of the heat source. That applies to both HERMS and RIMS.

If you have your temperature sensor in the mash or at the tun outlet, there is a very high chance that the wort will be overheated at the heat source.

Remember, the enzymes are in the wort...not in the mash bed. The temperature of the mash bed is not important, the maximum temperature of the wort is.

 

[John Eberly]

Snuggie, as I understand it decoction is done on the thick part of the mash first which is meant to leave enzymes behind in the liquid in the MT. In a triple decoction the last step is to heat the thin part of the mash which wipes out enzymes.
You do kill enzymes but that is part of the point, keeping malt character in the finished beer.

Now please tell me you were not just trolling us -

 

[augiedoggy]

Snuggie, as I understand it decoction is done on the thick part of the mash first which is meant to leave enzymes behind in the liquid in the MT. In a triple decoction the last step is to heat the thin part of the mash which wipes out enzymes.
You do kill enzymes but that is part of the point, keeping malt character in the finished beer.

Now please tell me you were not just trolling us -

if you were responding to me I was not trolling.. I have done two decoction brews in my life and did use a portion of the thick mash to heat.. I just assumed when that portion was heated the enzymes would be destroyed and when it was added back to the mash more would be denatured but I understand it gives more malt flavor as basically unfermentables... I mention it only because of a heat discussion I had with a friend who brews recently and always does decoction mashes claiming it raises his efficiency.. I dont see how.

 

[Smellyglove]

if you were responding to me I was not trolling.. I have done two decoction brews in my life and did use a portion of the thick mash to heat.. I just assumed when that portion was heated the enzymes would be destroyed and when it was added back to the mash more would be denatured but I understand it gives more malt flavor as basically unfermentables... I mention it only because of a heat discussion I had with a friend who brews recently and always does decoction mashes claiming it raises his efficiency.. I dont see how.

If he is only using infusion mashes I can see how that will affect his efficiencies as some of the starch granules are not soluble at for instance 65C. If he uses infusion to get to mash out (or doesn't do mash out) he goes straight into denaturing enzymes (when doing a mash out). If he would mash for maybe 30min-60 min at 72C in a stepped mash, then also do a mash out, I don't see (or have experienced) that a decoction would give him any noticeable bigger yield.

 

[postalbunny]

If he is only using infusion mashes I can see how that will affect his efficiencies as some of the starch granules are not soluble at for instance 65C. If he uses infusion to get to mash out (or doesn't do mash out) he goes straight into denaturing enzymes (when doing a mash out). If he would mash for maybe 30min-60 min at 72C in a stepped mash, then also do a mash out, I don't see (or have experienced) that a decoction would give him any noticeable bigger yield.

Doing a dec/step mash woudl also extend his mash time... I'm positive the part of the mash that was boiled/heated would be denatured and "stop" converting. I doubt he's seeing any improvement in eff from that. Perhaps returning it to the MLT and heating the mash higher makes for easier mash out similar to a real "mash out" when you raise to 168. However; compared to a 60 min mash he may be seeing more efficiency due to the extra 30-60mins he spent mashing in total. I'd be curious if he got similar eff if he did the same beer with total mash time the same.

My best guess...

 

[postalbunny]

I use a rims but I recirculate the entire time on my setup using a super ULWD cartridge heater to not denature enzymes... I average 90% efficiency this way with only 1.5-2gpm max flowrate..
Does the spike setup have a way to keep the liquid in the hlt stirred and consistent? if not it may be why they suggest doing it the way they do.
I did not have consistent results with my herms system until I used a pump to keep the hlt water moving.

Not sure on the spike setup, but in mine and most i've seen there is a pump recirculating the HLT water. There is simply too much stratification to get a solid enough temp to not recirc. Maybe on a 5-10g HLT you wouln't have as big of an issue. But I've got dual 4500 elements and noticed temp variations as high as 10degF between the bottom and top of my 20g HLT when recirc is off (i often leaf it off during initial warm up or cleaning due to overshooting and steady temp not being that big of a deal).

I've seen a few post where people setup mixers... but imo recirc is better. On my setup I've got the HLT output tied to a 3way ball valve that can output over to the MLT during sparge so i don't have to move any hoses or touch hot water. After mash-out I turn MLT's output toward the brew kettle and turn the HLT output toward the MLT while throttling both to get a take 30-45mins to reach boil volume.

 

[Smellyglove]

Doing a dec/step mash woudl also extend his mash time... I'm positive the part of the mash that was boiled/heated would be denatured and "stop" converting. I doubt he's seeing any improvement in eff from that. Perhaps returning it to the MLT and heating the mash higher makes for easier mash out similar to a real "mash out" when you raise to 168. However; compared to a 60 min mash he may be seeing more efficiency due to the extra 30-60mins he spent mashing in total. I'd be curious if he got similar eff if he did the same beer with total mash time the same.

My best guess...

I've done a few decoctions in beers I've brewed several times, and total mashtime has been pretty equal comparing to the non-decocted versions, and don't see much of an efficiency bump.

 

[postalbunny]

I've done a few decoctions in beers I've brewed several times, and total mashtime has been pretty equal comparing to the non-decocted versions, and don't see much of an efficiency bump.

That's interesting... i got my instructions from reading up BYO article which has several rest and 15-30 mins rest. One at 125, 30min, then 149 for 30 min, then 170 for 30 with 15-30 min heat times inbetween. I'd be curious if your shortened version gets the same character... i always suspected just boiling some of the mash would give a good amount of flavor and possibly save some time.

I was referring to OP's friend possibly doing a tripple decoc taking 2.5-3hrs and getting better efficiency because his normal 60hr mashes were not getting it done... maybe bad crush, lower than normal temp and the longer mash makes up for the miss.

 

[Smellyglove]

That's interesting... i got my instructions from reading up BYO article which has several rest and 15-30 mins rest. One at 125, 30min, then 149 for 30 min, then 170 for 30 with 15-30 min heat times inbetween. I'd be curious if your shortened version gets the same character... i always suspected just boiling some of the mash would give a good amount of flavor and possibly save some time.

I was referring to OP's friend possibly doing a tripple decoc taking 2.5-3hrs and getting better efficiency because his normal 60hr mashes were not getting it done... maybe bad crush, lower than normal temp and the longer mash makes up for the miss.

Sorry, I forgot to say how I do my decoctions. Yeah I "cheat". I'm only after the maillards. With my lacking knowledge of decoctions I don't see why just resting the decoction at mash temp for an extended time would give me a different result than doing that rest in the main mash tun. So draw my (did draw, I don't do decoctions anymore) decoction portion just to boil it. I've been boiling them for about half an hour, in between temp-rises and a bit further into the next sacc-step. That's why the total time wasn't any greater than a straight step mash. I've only done two rests in the same mash.

 

[Genuine]

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.

 

[Blazinlow86]

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.

I have noticed the same thing on my herms if running the recirculation slower than fullish speed. If running full speed the temps in and out match perfectly between the hlt and MLT. Cheers

 

[augiedoggy]

I have noticed the same thing on my herms if running the recirculation slower than fullish speed. If running full speed the temps in and out match perfectly between the hlt and MLT. Cheers

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.

 

[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