RIMS vs HERMS vs Recirculating Direct Heating

[doug293cz]

So here is the thing... let's say our mash is at 140F and we want a mash temp of 150F. Let's say we are recirculating through the bed at a set flow of say, 1 GPM. The higher we heat the mash liquid (via HERMS, RIMS or kettle bottom) the faster the mash heats up.

If we return the mash liquid at 150F, it will take forever to heat the mash up. If we return the mash liquid at 160F, it heats up faster. 170F, 180F, 190F and 200F. It just gets faster.

So what is the highest practical mash liquid return temp that doesn't harm the mash ?

If you return the wort at 170˚F, or hotter, you can assume that all the enzymes in the returned wort have been denatured. Once all the wort has been thru the RIMS, you will have little, or no, enzymes left. If you run at a return temp of 165˚F, you may have no enzymes left after after 15 - 30 minutes. If your control temp prob is located where the hottest wort is, your control temp should be no higher the 5˚F above your target mash temp. You really need to do some temp probing in the bulk of the mash to characterize the difference between the control setpoint temp and the actual mash temp. If you don't do this, you will be flying blind,

Brew on

 

[brewman !]

Pretty much every brewing textbook you read.

Give me a Title and page number. Palmer ?

 

[Paulaner]

Give me a Title and page number. Palmer ?

Palmer isn't a brewing textbook. Professional textbooks. Not some home brewer who wrote a book.

 

[brewman !]

If you return the wort at 170˚F, or hotter, you can assume that all the enzymes in the returned wort have been denatured. Once all the wort has been thru the RIMS, you will have little, on no, enzymes left. If you run at a return temp of 165˚F, you may have no enzymes left after after 15 - 30 minutes. If your control temp prob is located where the hottest wort is, your control temp should be no higher the 5˚F above your target mash temp. You really need to do some temp probing in the bulk of the mash to characterize the difference between the control setpoint temp and the actual mash temp. If you don't do this, you will be flying blind,

I totally agree with this and thus think we've been doing mash temp control wrong for a long, long time.

Right now people either measure the temp of the mash itself or they measure the return temp. I don't know of anyone measuring both and using them in a control scheme.

If people are measuring and controlling on mash temp then the return temp gets out of control because the heat source goes to 100% until the mash reaches temp. There is no control of the return temp.

If people are measuring and controlling on return temp and set it the same as the desired mash temp, it takes the mash forever to get there because as the mash approaches the return temp, the delta T between the return temp and the mash itself goes to zero and the heat transfer gets real slow.

The HERMs might get around this issue if the operator sets the HLT temp to 5F above the mash temp and if the HERMS coil is big enough and if the mash flow rate is high enough.

RIMS has the ability to overheat the return liquid. For sure kettle bottom, especially propane direct heated kettle bottom has the ability to overheat the return liquid.

The ideal mash control system needs to monitor and control on both return temp and mash temp.

 

[brewman !]

Palmer isn't a brewing textbook. Professional textbooks. Not some home brewer who wrote a book.

Again, give me a title and a page number.

Blazinlow86 just said he can raise his mash 10F in 5 minutes. That is 2F per minute, which is 1.427C per minute. What damage is he causing his mash ?

 

[Blazinlow86]

So this with the water in the HLT set to the desired mash temp ?

Yup. I just set the temp I want and the mash follows along. Not sure if it's relevant to the conversation but I also heat my strike water using the herms as I like to keep my hlt full until I flysparge. Cheers

 

[brewman !]

Yup. I just set the temp I want and the mash follows along. Not sure if it's relevant to the conversation but I also heat my strike water using the herms as I like to keep my hlt full until I flysparge. Cheers

I think that is way better than allowing a RIMS element to run at full output, uncontrolled.

 

[vtipsy]

TBA does generally take a long period of heating at boiling or higher temperatures. Typical mashing practice does not fit that condition.

TBA which is measured by the TBI or Thiobarbituric Acid Index, is typically something that happens during the boil (on the professional scale) now on our scale since we're heating the mash directly this becomes a problem on our scale.

Guys, this is somewhat contradictory.

I'm wondering at the rate at which thiobarbituric acid is formed. Will a temporary temperature spike, say +5˚C for 10 seconds (passing through a RIMS tube and back into the mash) be long enough to form TBA at a significant level.

 

[brewbama]

So here is the thing... let's say our mash is at 140F and we want a mash temp of 150F. Let's say we are recirculating through the bed at a set flow of say, 1 GPM. The higher we heat the mash liquid (via HERMS, RIMS or kettle bottom) the faster the mash heats up.

If we return the mash liquid at 150F, it will take forever to heat the mash up. If we return the mash liquid at 160F, it heats up faster. 170F, 180F, 190F and 200F. It just gets faster.

So what is the highest practical mash liquid return temp that doesn't harm the mash ?

In my RIMS controlled by a PID, the temp in the RIMS tube does not exceed the set point of the controller.

When I program the set value (SV) to 150*F the temp of the fluid flowing across the temp probe, which is about 1.75” downstream from the heating element, sends a signal (perceived value — PV) to the controller. That SV/PV difference (error) is calculated and the controller provides power to the element to decrease the error. That power may be 100% initially but rarely and only for extremely short periods. The PID senses the rate increase and reduces power so it doesn’t overshoot the SV.

The cycle continues until all the fluid in the mash flows across the temp sensor and is brought to the same temp. At no point in the cycle is the wort ever heated to a temp higher than the SV. Sure, it may overshoot by 1*F but it simply does not overshoot by 10/20/30*F ever.

You’re not heating the entire mash with the element at one time — only the small 1.25 cup portion in the tube until the entire wort volume passes thru the tube multiple times. It requires very little power to increase the temp of that small amount.

Enzymes do not denature because they are not heated beyond the SV. If the wort was heated beyond the SV the temp probe would sense it and display the temp.

(Edited to include measured distance between temp probe and element, and volume of RIMS tube)

 

[golfindia]

In my RIMS controlled by a PID, the temp in the RIMS tube does not exceed the set point of the controller.

When I program the set value (SV) to 150*F the temp of the fluid flowing across the temp probe, which is about 1” downstream from the heating element

Exactly. If you are doing RIMS by measuring temp "at the return" or "in the mash" you're doing it wrong.

 

[augiedoggy]

So here is the thing... let's say our mash is at 140F and we want a mash temp of 150F. Let's say we are recirculating through the bed at a set flow of say, 1 GPM. The higher we heat the mash liquid (via HERMS, RIMS or kettle bottom) the faster the mash heats up.

If we return the mash liquid at 150F, it will take forever to heat the mash up. If we return the mash liquid at 160F, it heats up faster. 170F, 180F, 190F and 200F. It just gets faster.

So what is the highest practical mash liquid return temp that doesn't harm the mash ?

when you do it that way you are actually mashing some of the liquid at 160f and it changes the outcome as far as mash temps from what the software estimates at a certain mash temp..

the real question is if you want to mash at 150 why is your mash at 140? some sort of step mash or poor strike water calculations would be the only reason this would occur right?

 

[augiedoggy]

In my RIMS controlled by a PID, the temp in the RIMS tube does not exceed the set point of the controller.

When I program the set value (SV) to 150*F the temp of the fluid flowing across the temp probe, which is about 1.75” downstream from the heating element, sends a signal (perceived value — PV) to the controller. That SV/PV difference (error) is calculated and the controller provides power to the element to decrease the error. That power may be 100% initially but rarely and only for extremely short periods. The PID senses the rate increase and reduces power so it doesn’t overshoot the SV.

The cycle continues until all the fluid in the mash flows across the temp sensor and is brought to the same temp. At no point in the cycle is the wort ever heated to a temp higher than the SV. Sure, it may overshoot by 1*F but it simply does not overshoot by 10/20/30*F ever.

You’re not heating the entire mash with the element at one time — only the small 1.25 cup portion in the tube until the entire wort volume passes thru the tube multiple times. It requires very little power to increase the temp of that small amount.

Enzymes do not denature because they are not heated beyond the SV. If the wort was heated beyond the SV the temp probe would sense it and display the temp.

(Edited to include measured distance between temp probe and element, and volume of RIMS tube)

mine works the same way.

Not all rims systems are efficient like this though in fact I think most off the shelf setups are not implemented correctly whether it be sizing the element or flow... For example if you have a 1500w 12" element in an 18" rims tube and your trying to raise the temp like 3 degrees and the flow is too high as many homebrewers do for some reason then you have an element that stays on pretty much 100% trying to catch up to the 3 degree setpoint, meanwhile your denaturing all the wort that comes in direct contact with the element surface but then mixes with the much cooler wort that goes through the rims but misses the element before it sees the probe downstream.. this is bad IMO. same happens when trying to step mash. sure it works but I believe the result is more enzyme damage and slightly less fermentable wort. it seems more like a decocton that way to me but without the benefits

Even my 3 bbl rims system is taking a hit on efficiency compared to my home rims when I need to raise the temps more than the delta since the elements will stay on 100% and the proof is the film thats left behind cooked onto the element surface vs my home rims which stays completely clean.
There are alot of brewers that just look at a temp probe in the MT and see they need to raise the temp a few degrees and turn the rims or herms on for a few mins to heat the MT over setpoint and then manually mix as well which I think is counter productive to how it should and could work.

 

[augiedoggy]

I totally agree with this and thus think we've been doing mash temp control wrong for a long, long time.

Right now people either measure the temp of the mash itself or they measure the return temp. I don't know of anyone measuring both and using them in a control scheme.

If people are measuring and controlling on mash temp then the return temp gets out of control because the heat source goes to 100% until the mash reaches temp. There is no control of the return temp.

If people are measuring and controlling on return temp and set it the same as the desired mash temp, it takes the mash forever to get there because as the mash approaches the return temp, the delta T between the return temp and the mash itself goes to zero and the heat transfer gets real slow.

The HERMs might get around this issue if the operator sets the HLT temp to 5F above the mash temp and if the HERMS coil is big enough and if the mash flow rate is high enough.

RIMS has the ability to overheat the return liquid. For sure kettle bottom, especially propane direct heated kettle bottom has the ability to overheat the return liquid.

The ideal mash control system needs to monitor and control on both return temp and mash temp.

again.. this is the issue I try to account for when using a 36" long heating element 5/8" diameter in a 1" tube at a fairly low flow rate with a lower wattage (1800w) and very low watt density element... Its also one of the main reasons I believe that I average 91% efficiency.

 

[Cavpilot2000]

A metaphor I've heard used to compare RIMS to HERMS is: A HERMS system is like a school bus, big and safe but can't turn or stop quickly. A RIMS system is like a sports car, fast and maneuverable, but more likely to slam into a telephone pole.

I love that analogy - very accurate too!

 

[augiedoggy]

^ ah but you put the school bus driver in the sportcar and you could have the best of both worlds because of the superior handling and performance and smart use of it.. The problem is too many rims users without a full understanding that use it like a teenager would a sportcar.

 

[Blazinlow86]

I always looked at it as rims is for no hlt or a gas fired manual controlled hlt and herms is for a electric hlt setup. I can't see how a rims would give better "performance" than a properly built Herms setup. Cheers

 

[BrunDog]

Heat liquid... or heat liquid to heat liquid. That's the fundamental difference.

 

[schematix]

You can overcome the inefficiency of two heat transfers by using very large elements in the HLT and then a long HX coil.

Seems silly to me.

 

[Blazinlow86]

Heat liquid... or heat liquid to heat liquid. That's the fundamental difference.

Of course but your using liquid that you have to heat regardless to heat that mash liquid. So it's basically free. In order to just heat the mash liquid directly without
using the already heated hlt liquid would require a 3rd heating setup unless I'm missing something or we are talking about using a Herms in a non traditional mash setup which I would agree makes no sense. Cheers

 

[Blazinlow86]

You can overcome the inefficiency of two heat transfers by using very large elements in the HLT and then a long HX coil.

Seems silly to me.

Depends on the set-up I guess. Mine uses the standard 5500w element and a 50ft coil. Nothing crazy. It can step mash as quickly as is required and maintains temp without any offsets. Using a rims setup with my system would be more complicated with more parts and no advantage. This part of the process I feel doesn't need to be over complicated. Cheers

 

[mabrungard]

when you do it that way you are actually mashing some of the liquid at 160f and it changes the outcome as far as mash temps from what the software estimates at a certain mash temp..

the real question is if you want to mash at 150 why is your mash at 140? some sort of step mash or poor strike water calculations would be the only reason this would occur right?

The only thing that matters is the temperature of the wort. The temperature of the mash bed does not matter. If you're flowing hotter wort through a cooler mash bed, eventually that 'wave' of hotter wort will make its way through the entire bed and the whole system is at temperature. It's unreasonable to think that you can instantly step the temperature of your entire system up. It does take time and watts to add and distribute heat.

 

[augiedoggy]

The only thing that matters is the temperature of the wort. The temperature of the mash bed does not matter. If you're flowing hotter wort through a cooler mash bed, eventually that 'wave' of hotter wort will make its way through the entire bed and the whole system is at temperature. It's unreasonable to think that you can instantly step the temperature of your entire system up. It does take time and watts to add and distribute heat.

I totally agree with you. not sure how your interpreting what im saying.. what im trying to say is a poorly designed rims can effectively heat the wort around the element to much higher than setpoint but by the time it reaches the probe at the opposite end of the tube some of the wort that also made it through the tube but didnt come in contact with the rims element surface will mix and bring the temp back down..to me thats a less efficient way to use the rims and some wort will effectively see very high element surface temps this way.

 

[augiedoggy]

I always looked at it as rims is for no hlt or a gas fired manual controlled hlt and herms is for a electric hlt setup. I can't see how a rims would give better "performance" than a properly built Herms setup. Cheers

herms is very slow to react and climb vs rims and its even more difficult to correct things like temp overshoot. Ive owned and used both and would never go back to herms myself but I could see how it would work perfectly fine for some depending on system setup.

 

[BrunDog]

Of course but your using liquid that you have to heat regardless to heat that mash liquid. So it's basically free. In order to just heat the mash liquid directly without
using the already heated hlt liquid would require a 3rd heating setup unless I'm missing something or we are talking about using a Herms in a non traditional mash setup which I would agree makes no sense. Cheers

True. This is why I personally built an "HLT free" system and heat on the fly. If you have an HLT... I will agree it doesn't make a heck of a lot of sense to add a third element for RIMS. If you boil in your BK, then that might make sense.

 

[augiedoggy]

at the brewery we heat our sparge water to 170 while the mash is reciculating through the rims... in that scenero I think it actually saves us time and headache... we sometimes do a proper "mashout by raising the mash with the rims and sometimes we just switch over to sparging and let the sparge water perform the mashout... because we often have to add more water to the HLT after doughing in a herms would not really be usful because by the time it got to the proper temp much of the conversion would be done since I find a lot is done in the first 15 minutes.

 

[Blazinlow86]

herms is very slow to react and climb vs rims and its even more difficult to correct things like temp overshoot. Ive owned and used both and would never go back to herms myself but I could see how it would work perfectly fine for some depending on system setup.

I guess I never really considered the climb speeds that closely and admittedly I don't do many step mashes but it usually takes appx 5 mins to raise 10f as long as I run it full speed on a typical 18g batch. is that fast enough? I have a heating element and some extra pids ssrs etc so I could build a rims setup if the quicker climbs are beneficial to step mashing. I control the heating element via the hlt output temp so I don't think it's possible to overshoot on my config. Cheers

 

[brewbama]

at the brewery we heat our sparge water to 170 while the mash is reciculating through the rims... in that scenero I think it actually saves us time and headache... we sometimes do a proper "mashout by raising the mash with the rims and sometimes we just switch over to sparging and let the sparge water perform the mashout... because we often have to add more water to the HLT after doughing in a herms would not really be usful because by the time it got to the proper temp much of the conversion would be done since I find a lot is done in the first 15 minutes.

I’d like to see the brewery-sized RIMS system. I run puny 5 gal batches with mine.

 

[Paulaner]

I guess I never really considered the climb speeds that closely and admittedly I don't do many step mashes but it usually takes appx 5 mins to raise 10f as long as I run it full speed on a typical 18g batch. is that fast enough? I have a heating element and some extra pids ssrs etc so I could build a rims setup if the quicker climbs are beneficial to step mashing. I control the heating element via the hlt output temp so I don't think it's possible to overshoot on my config. Cheers

Running it too fast becomes detrimental to your wort see the post on pg 1 about TBI.

 

[augiedoggy]

Running it too fast becomes detrimental to your wort see the post on pg 1 about TBI.

also contributes to channeling in the grainbed which you might only see as lower efficiency or dryer beer than expected.

 

[augiedoggy]

I’d like to see the brewery-sized RIMS system. I run puny 5 gal batches with mine.

stout offers it.. its a regular rims though like bobby sells they also have the 3bbl herm setup but its avaliable from the manufacturer who made our kettles (stout sells it too ) a friend who owns a nano is using that version while I decided to go rims based on my home brewing system experience with both.
We are only averaging about 85% eff at the brewery and still trying to dial things in. a better false bottom is on my list

our rims is custom being extremely long and ulwd.. ill see if I have any pictures.

 

[augiedoggy]

I guess I never really considered the climb speeds that closely and admittedly I don't do many step mashes but it usually takes appx 5 mins to raise 10f as long as I run it full speed on a typical 18g batch. is that fast enough? I have a heating element and some extra pids ssrs etc so I could build a rims setup if the quicker climbs are beneficial to step mashing. I control the heating element via the hlt output temp so I don't think it's possible to overshoot on my config. Cheers

Your setup seems to work much better than the one I had. I had made a few mistakes with mine since it was my first year brewing. I had issues with uneven temps in my HLT and had to add a pump just to keep stirring the water and it got to the point where I just decided I wanted to try a rims. The rims just seems to be logically more efficient for me and I could actually clean it where with the coil I was always worried about the inside getting nasty at the time.

 

[brewbama]

We are only averaging about 85% eff at the brewery and still trying to dial things in.

When you say 85% efficiency. How are you measuring efficiency? Is this Mash efficiency? OrBrewhouse efficiency? I’ve seen contradictory calculations for each. It helps us understand each other if we’re using the same definition.

 

[augiedoggy]

When you say 85% efficiency. How are you measuring efficiency? Is this Mash efficiency? OrBrewhouse efficiency? I’ve seen contradictory calculations for each. It helps us understand each other if we’re using the same definition.

brewhouse as calculated by beersmith 3 pro. I use beersmith2 at home (not that it matters) to get 91% average efficiency and if im not mistaken my mash efficiency is usually much higher than that. some beers like wheat beers tend to hit a bit lower around 88-89%

 

[brewbama]

Ah. I use BS as well so we’re talkin the same language. Mash efficiency is where the RIMS increased my Mash efficiency consistently to 90% +/- 2% measured across many brews (calc by BS).

With Brewhouse efficiency how a mash is performed is simply one of many other factors. For instance, at the completion of the boil simply draining the BK into a fermenter would dramatically increase BH efficiency. However, I prefer to whirlpool the trub and leave behind the cloudy wort. I prefer clear, clean wort in my fermenter so my BH efficiency suffers as a result. I imagine a pro would simply use centrifugal force to separate the trub. I use 70% as a planning number and generally get +/- 2% there as well.

 

[augiedoggy]

Ah. I use BS as well so we’re talkin the same language. Mash efficiency is where the RIMS increased my Mash efficiency consistently to 90% +/- 2% measured across many brews (calc by BS).

With Brewhouse efficiency how a mash is performed is simply one of many other factors. For instance, at the completion of the boil simply draining the BK into a fermenter would dramatically increase BH efficiency. However, I prefer to whirlpool the trub and leave behind the cloudy wort. I prefer clear, clean wort in my fermenter so my BH efficiency suffers as a result. I imagine a pro would simply use centrifugal force to separate the trub. I use 70% as a planning number and generally get +/- 2% there as well.

at home I use 2 hop spiders as well as a fine stainless braided line on my bk diptube to filter anything out as it goes through the plate chiller. so I generally get no noticeable trub in my conicals
at the brewery we use hop bags (as many do with electric) and we whirlpool.. our hop efficiency is actually over 100% even with the bags. so much more efficient weve had to adjust our recipes vs the test system. we do get more trub in the conicals at the brewery.
either way we measure post chilled wort gravity for efficiency so not sure how it would matter

 

[Blazinlow86]

Your setup seems to work much better than the one I had. I had made a few mistakes with mine since it was my first year brewing. I had issues with uneven temps in my HLT and had to add a pump just to keep stirring the water and it got to the point where I just decided I wanted to try a rims. The rims just seems to be logically more efficient for me and I could actually clean it where with the coil I was always worried about the inside getting nasty at the time.

Ah yes I recirculate the hlt and I run my clean sparge water thru the hlt to clean it out. Cheers

 

[Blazinlow86]

Running it too fast becomes detrimental to your wort see the post on pg 1 about TBI.

Don't believe everything you read online. I brew close to 500gallons a year on the system with no issues. Cheers

 

[Blazinlow86]

also contributes to channeling in the grainbed which you might only see as lower efficiency or dryer beer than expected.

As long as you adjust your grist to your setup you won't have any issues with channeling. I condition and mill at .045 and always use rice hulls if im using wheat etc. You can tell when your pumping too fast by watching the sight glass level. If it drops your going to fast. Admittedly efficiency *could* take a hit but in my personal experience it hasn't and its not worth the extra effort to save a few dollars. I feel Efficiency is the least important factor overall. I'm mostly concerned with consistency and end product. Costs aren't much a concern. Cheers

 

[Paulaner]

Don't believe everything you read online. I brew close to 500gallons a year on the system with no issues. Cheers

Has nothing to do with online or in your case anecdotal, this is verbatim from Kunze.

 

[Blazinlow86]

Has nothing to do with online or in your case anecdotal, this is verbatim from Kunze.

No idea. All I can say is it works great for me. Believe whatever you like. Cheers

*Edit*
I took a look at the previous posts and i couldn't see anything that relates to TBI with how fast the mash liquid is turned over. So just to clarify I'm not running my heating element full. I'm talking about my recirculation rate. Im thinking thats were the misconceptions about poor performance with a Herms comes from. At least on my system I HAVE to run the circulation at the full speed in order to maintain the same temp between my hlt and MLT. If for example I messed up my milling and cannot run it full speed it will take along time to heat as others have noted and my mash temps won't match the hlt .chee ch