HERMS vs. RIMS (electric) Pros and Cons

HBTers, I think it would be a good idea to put together a list of brainstormed pros and cons related to selecting either a HERMS or a RIMS system. Let's start with brainstorming for a while BEFORE posting any disagreement with previously posted pros and cons. Let the list grow a bit before knocking anything down.

The basic purpose of a HERMS and RIMS is for accurate temp control throughout the mash whether it's for a single rest or low to moderate stepping.
Let's try to ignore pros and cons to recirculation in general and talk about the contrast between the two methods. In other words, both help with wort clarity due to the long "vorlauf". No need to list that.

To normalize on what we're talking about assume these basic definitions:
HERMS - Thin mash is circulated through a coil immersed in the HLT and returned to the top of the mash. The HLT is filled with future sparge water held at a temperature that will impart desired heat into the mash wort. This is often controlled by monitoring the coil's output temp and applying heat to the HLT water as necessary.

RIMS - Thin mash is circulated through a tube in which an electrical heating element is installed and then returned to the top of the mash. Temp is controlled by monitoring the tube output and regulating the heating element based on that temp.

I'll start:
HERMS
Pro:
Guaranteed gently heating of mash.
Coil may be integrated as a chilling path later.
Compact, stays within vessel.
Can be employed with manual control (turn HLT heat on).

Con:
Benefits from (if not requires) HLT water agitation/stirring (can use second pump for this).
Requires sparge water to be heated earlier in the process (heat efficiency loss)


RIMS
pro:
Can be made portable.
Can be employed immediately without heating sparge water first.
con:
Can scorch wort if oversized element or poorly controlled.

Discuss, I'll update this list ongoing.

RIMS Pro- sparge and strike water can be pumped through the RIMS tube to reduce time taken to reach temperatures (in addition to burner or element).
Also reduces time taken to get the finished wort boiling by pumping the sparge through the RIMS on the way to BK (and stops conversion).

HERMS:
Pros
•maintain exact mash temp without heat stratification through heating circuit
•once calibrated it is extremely easy to maintain desired temps (e.g., 4º offset for losses)

Cons
•mostly useless for step mashes or adjusting mash temp, unless you use a vessel other than HLT or overshoot sparge temps

RIMS
Pros
•Great for step mashes so long as the element is sized properly

Cons
•requires extra equipment (if you have a immersion coil, you already have a HERMS you just aren't using it)
•temp stratification within heating circuit

BRu that is a really good idea that I never thought of.

I really prefer to have both RIMS and HERMS. I use an immersion chiller that doubles for a HERMS coil. I find that I use the RIMS when doing a step mash and the HERMS for single infusion or any rest that is long enough to warrant it.

Any room for steam injection RIMS in this discussion?, or plate heat exchange HERMS.

How much longer before arguing?. I'll delete if necessary. Why is a herms useless for step mashes? From what i've seen (limited use), my element would easily raise temps in hlt quick enough to step mash with. Does it take to long to raise temps with recirculating?

And one more pro for herms, it can double as a chiller.

I think steam is its own category...

Wild, it depends how you use it. If you overshoot the sparge temps in the HERMS or calculate a temperature equilibrium, maybe a step can be realistic. But both of those are a hassle IMO. If you set a HLT to your next step temp + offset, and expect it to come to temp, the step is going to be very slow. That is because as the wort approaches the setpoint temp, the temp differential becomes smaller and smaller, slowing down heat exchange.

It can work, it just isn't the best way IMO. RIMS is much more straight forward and effective for stepping. That has been my experience anyway.

RIMS Tube is cool.

It's no secret that I am a RIMS brewer. I just wanted to make a few comments on some misconceptions of RIMS Breweries. Some brewers view RIMS brewing as risky due to the damage that could result from a "Stuck Mash". This can however, be prevented by adding an appropriate flow switch or utilizing the "Alarm Relay" in the PID Temperature Controller to protect the apparatus. I also think that the danger brewers percieve in scortching the Mash in a RIMS setup may be over stated. I think that there have been some alleged claims on how easily the wort can be scortched but I think the reality of it is that there is very little hard evidence. I know there have been a couple brewers who have even tried using lower watt (~1500 watts), high density elements in their RIMS with success. As innovative homebrewers push the envelope the mystique over alleged mash scortching will be lifted.

Boerderij_Kabouter said:

Wild, it depends how you use it. If you overshoot the sparge temps in the HERMS or calculate a temperature equilibrium, maybe a step can be realistic. But both of those are a hassle IMO. If you set a HLT to your next step temp + offset, and expect it to come to temp, the step is going to be very slow. That is because as the wort approaches the setpoint temp, the temp differential becomes smaller and smaller, slowing down heat exchange.

It can work, it just isn't the best way IMO. RIMS is much more straight forward and effective for stepping. That has been my experience anyway.

Click to expand...

The thin mash passing through the HERMS coil reaches the temp of the HLT by the time it outputs, so the time to perform a step would be how long it takes to bump up the heat in the HLT plus however long it takes to recirculate the entire mash volume through the coil.

I haven't tested stepping in my system, but based on how quickly it raises temp, and my recirculation flow rate, I think a 30 degree step could be achieved in about 15 minutes.

From what I understand, the limit of how fast you can step in HERMS has to do with the total volume of sparge water in the HLT and the volume of mash. While a RIMS applies direct heat to only the mash mass, it's usually a lower wattage (for good reason). On the other hand, while HERMS adds another ~5-10 gallons of thermal mass, it also tends to have 3x the heating power.

klyph said:

The thin mash passing through the HERMS coil reaches the temp of the HLT by the time it outputs, so the time to perform a step would be how long it takes to bump up the heat in the HLT plus however long it takes to recirculate the entire mash volume through the coil.

I haven't tested stepping in my system, but based on how quickly it raises temp, and my recirculation flow rate, I think a 30 degree step could be achieved in about 15 minutes.

Click to expand...

Right. And 15 minutes I would count as a ramp, not a step. Tomato tomahto, perhaps, but for me, IME it takes longer than 15 minutes and is a pain, and just isn't good enough for me. That's why I call it a con.

Also, a standard RIMS tube uses just as much volume as a HERMS coil. Just for reference, a 25'x1/2" coil with about 5' of tubing connections uses an extra 1.25 quarts. Not much....

Agreed, recirculation path volume is a wash.

I was going to raise the point of cleaning, but that depends greatly on what kind of RIMS tube you have and whether your RIMS/HERMS is SS or copper.

So I used to use a RIMS but I had a scorched batch (one was enough) so I switched to a HLT HERMS that was manually controlled via the burner. Now I have a separate HERMS chamber that is PID controlled. Of all of them, I like the latest the best.





All three were able to transfer heat the same but each have their own weakness.

RIMS - Heated the sames as the rest, auto control, liked the to set and forget aspect, but could and did scorch. (tried to market the stuff as a stienrauchbrau but nobody was buying it)

HLT HERMS - Larger thermal mass held heat better but took longer to heat up and was manually controlled. I think the major weakness for me though was that unless I heated up the entire HLT volume, I had to wait longer to recirculate after dough in while I was heating additional water to cover the coil. (I know I could also heat in my kettle.) This added a little more time to the brew day. Oh, and since the heating medium was also the sparge water, I aways had to cool it back down after I ramped to mash out temp.

Separate HERMS - Nice Auto control like the RIMS, no chance of scorching, smaller chamber volume heats up quicker and therefore only the strike water needs to be heated up to start a mash and recirculate. I think the one weakness of this setup compared to the HLT HERMS is that due to the lower thermal mass of the chamber liquid, if there is a large differental between the mash and the chamber, it will cool the chamber faster than the element can hold the temp. (currently 1500W since I wanted to stay on an existing 20 amp 120 circuit) This would only be an issue with something like an acid rest.
The few brews I've done on this have been great and required much less attention than the manual HLT HERMS brews. I'm not sure if an electric HLT would be better either. There is still the wait for the additional water to heat up (unless strike water was made in the kettle, but then you couldn't do a double hitter).

I've been away from brewing for over a year now (life, work, blah, blah). I happen to be planning my 3rd. major build and I'm in the process of analyzing if I want to stick with my HERMS or go the RIMS route. So this topic is very timely!

I currently have a separate HERMS chamber similar to Bigscience's. The difference being that I used a 1 gallon cooler w/ a bucket heater controlled by a PID. I also use an aquarium pump to bubble air inside the chamber to keep from getting stratification. [Blue cooler in picture - lid off]





And as Boerderij pointed out, it does a great job of maintaining mash temps and doing small adjustments but it just cannot handle step mashes. My new build will be completely electric (basement brewing) so I will have 240 available and can upgrade the heating element (from 1500W).

My only complaint is keeping the inside of the coild clean (I cannot easily remove it). After I brew I recirculate PBW through it and then rinse. But there's no way to get the standing water out of the coil. So that freaks me out a little. To the point that I recirculate some StarSan through it before I brew just in-case anything started to grow in there between brews. If I could find a better way to keep it clean/empty then I would be a happy camper. My only idea is to use compressed air to blow out the water after I clean it?

I forgot to mention... mashing-in can be a pain because you have to by-pass the HERMS. Unlike folks that have the HERMS coil in the HLT, I have to have my water temp in the HERMS chamber close to my strike water, if I don't, it can lower/raise the the strike water by a lot so bypassing it is what I do. This would be a lot easier using a RIMS.

I have had issues re-priming the pump after I move my hoses around to include the HERMS after the mashing in. Nothing major, but just one more thing to run around and deal with while you are trying to establish the HERMS recirculation.

On my new build (assuming I stick with a HERMS), I'm planning on adding a temperature sensor inside the HERMS so I can independently control the water temperature. I would only use this to get the water in the chamber equal to my strike water. And then once I start mashing-in, the water out sensor would take over and control the heating element. Hope this make sense.

Awesome idea for a thread Bobby.

caskconditioned said:

My only complaint is keeping the inside of the coild clean (I cannot easily remove it). After I brew I recirculate PBW through it and then rinse. But there's no way to get the standing water out of the coil. So that freaks me out a little. To the point that I recirculate some StarSan through it before I brew just in-case anything started to grow in there between brews. If I could find a better way to keep it clean/empty then I would be a happy camper. My only idea is to use compressed air to blow out the water after I clean it?

Click to expand...

This is exactly why I went to the trouble of having mine enter and exit through the side of the keg. PBW recirc, water rinse, gravity drain + air for good measure.

shroomzofdoom said:

Awesome idea for a thread Bobby.

Click to expand...

+1

Along with this discussion could we also include pics of your set ups and designs. I am in the beginning stages of converting from a 2 tier to a "want a be Brutus 10" and I am planning to stick with a HERMS set up. Although I could be convinced another wise.

Cheers

I noticed that a lot of people bend their HERMS coils to a single diameter and it usually takes up quite a vertical in the HLT. What about leaving it in more of a concentric like copper tubing is shipped? Maybe just two flat coils like that sitting lower in the HLT so you only have to fill to 4 gallons for recirculation. I suppose the challenge is that you still have to add more water for 10 gallon batches and you'll have to stop circulating while the HLT temp recovers.

Bobby_M said:

I noticed that a lot of people bend their HERMS coils to a single diameter and it usually takes up quite a vertical in the HLT. What about leaving it in more of a concentric like copper tubing is shipped? Maybe just two flat coils like that sitting lower in the HLT so you only have to fill to 4 gallons for recirculation. I suppose the challenge is that you still have to add more water for 10 gallon batches and you'll have to stop circulating while the HLT temp recovers.

Click to expand...

That sounds like a pro/con: The amount of water needed to cover the coil in the HLT. Or am I misunderstanding it?

I also thought that if I did go RIMS, I would have to add a mini boiler sight glass or something to ensure I saw flow at any given time, the thought of a stuck sparge and potential impact seems like a concern.

And if RIMS, a threaded plug to drain the water out of the unit at the end of brew day. Not sure if I am just being anal, but it seems like this might be a good idea, not for the coil as much as for general cleanliness. On the other hand--with correct mounting design---a hex would be filled with nothing but air at the end of brew day.

I have been in the planning stages of my new brew rig for a while and one of the biggest reasons I've been leaning toward HERMS is it will require less elements. If I go all electric... I need an element in the BK and one on the HLT with HERMS. If I go RIMS, I need one in the BK, one in the HLT and also one in the RIMS tube. (unless I'm missing something) I don't need to step mash and I can still mash out in 15 min or so.

Bobby_M said:

I noticed that a lot of people bend their HERMS coils to a single diameter and it usually takes up quite a vertical in the HLT. What about leaving it in more of a concentric like copper tubing is shipped? Maybe just two flat coils like that sitting lower in the HLT so you only have to fill to 4 gallons for recirculation. I suppose the challenge is that you still have to add more water for 10 gallon batches and you'll have to stop circulating while the HLT temp recovers.

Click to expand...

I built a "Pol" clone for my HERMS system so the depth of water in the HLT is influenced by the height of the heating element installed vertically through the bottom. I have considered rebuilding to orient the element on the horizontal.

I just did a complete overhaul/rebuild of my operation:

https://www.homebrewtalk.com/f11/its-done-testing-commence-tomorrow-198694/

I decided to go HERMS soley because of the scorch wort risk and my inability to do anything with electrical other than lighting myself up (mans gotta know his limits)...so building a PID was out of the question.

ALthough I do like the RIMS approach as well...

Is 25x1/2" the common path to take for building a HERMS?
I had seen somewhere that someone had used rigid 1/2" tubing, has anyone tried it before?
Any close ups of their HERMS connections and returns? (simple parts list)

SAMPLER said:

Is 25x1/2" the common path to take for building a HERMS?
I had seen somewhere that someone had used rigid 1/2" tubing, has anyone tried it before?
Any close ups of their HERMS connections and returns? (simple parts list)

Click to expand...

There are quite a few places on the forum where guys have posted up their HEX coils repleat with connections/returns...simple search would yeild a lot of information- it did for me!

I am so glad this is being done. I am still up in the air between RIMS and steam injection, so reading more and more review information on the RIMS vs. HERMS will help.

I HERMS so no input on a RiMS, 20ft 1/2 copper and both fired and 1500watt 220v elemt. controlled by a Johnson A419, probe in the mash tun return,
I strike in a round 149 to 151 and can hit 153 or 154 in less than 20 mins. the 1500watt can hold what ever for over an hour in a 50L HLT. w/ 13gal water constant recirculating with a Little Giant md2-sc pump

.

all copper silver Brazed permanent mounted, I flow top down cleans easy and completely drains

Henrythe9th said:

all copper silver Brazed permanent mounted, I flow top down cleans easy and completely drains

Click to expand...

Do you recirculate top down too? I go bottom up because I was worried about trapping air although I'm not sure if it would or not.

Thanks Bobby for starting this thread. Right now I'm a traditional three tier brewer, but I have been kicking around the idea of going with either a RIMS or HERMS in the next year.
This is helping a lot with my planning.

Bigscience said:

This is exactly why I went to the trouble of having mine enter and exit through the side of the keg. PBW recirc, water rinse, gravity drain + air for good measure.

Click to expand...

Ahhh, grasshopper! Very smart.

Don't mean to hijack this thread...From your pics it looks like you have a probe in the HERMS chamber as well as on the "out" side; is that correct? Do you mash-in via the HERMS or bypass it? Are you doing anything to stir/agitate the water?

caskconditioned said:

Ahhh, grasshopper! Very smart.

Don't mean to hijack this thread...From your pics it looks like you have a probe in the HERMS chamber as well as on the "out" side; is that correct? Do you mash-in via the HERMS or bypass it? Are you doing anything to stir/agitate the water?

Click to expand...

I'm not sure I follow you. I have a probe on the out flow of the MLT, one in the chamber to regulate the HEX via PID and another one on the out flow to see what the return temp is.

For dough in, I heat strike water in the HLT and drain the desired amount into the MLT and then add grain and mix. After it's well mixed, I start to slowly recirculate to hold the temp. I recirc the whole time.

I don't do any stirring for now. I did some initial tests to see if it made any difference and it did help the outflow temp to be a little higher but only when there was a larger differential to begin with. It also dropped the HEX temp. For maintaining a mash temp or even for mashout/ramps, I just turn up the HEX temp. I know there are other people who use a air pump to stir up the water but it seems like that could actually be robbing heat from the system. If I do go with a mixing system, I'd go with an overhead stirrer.

Bigscience said:

I'm not sure I follow you. I have a probe on the out flow of the MLT, one in the chamber to regulate the HEX via PID and another one on the out flow to see what the return temp is.

Click to expand...

Gotcha... I (currently) take the reading on the out flow and that's what the PID uses to turn the heating element on/off. When I built it a few years ago I thought it would be better since the out flow temp is really what's important. But on my new build I'm planning on doing something similar to what you have and incorporating a BCS controller. I think knowing both the chamber and out flow temps is better.

caskconditioned said:

Gotcha... I (currently) take the reading on the out flow and that's what the PID uses to turn the heating element on/off. When I built it a few years ago I thought it would be better since the out flow temp is really what's important. But on my new build I'm planning on doing something similar to what you have and incorporating a BCS controller. I think knowing both the chamber and out flow temps is better.

Click to expand...

Having the PID probe in the HLT is the way to go. In the event of a stuck sparge/pump failure, measuring the HEX output could lead to a massive overshoot in the HLT.

i'm in the process of building my first sculpture and chose to go hex over rims, mostly because i already had the IC, it's nearly impossible to scortch (rumor or not), and i can work it as a manual system until i get the automation in place.

I'm sure it is a newbie question, but why are we not including direct fire RIMS in the discussion?

There really is no particular reason. I guess it's because I already use a direct fire RIMS (manual mode) so I was thinking towards the future and picked the two most common alternatives. I'll start.

Direct Fire RIMS:
Pro:
Shortest recirculation path (little to no impact though).
Fastest heat steps.

Con:
Stuck recirculation for too long will scorch, no question.
Automating harder than electric options (pilot lights, etc).
Requires full false bottom to keep thick mash off heatable surface.
Requires heat resistant insulation on tun.

zymurgy101 said:

I'm sure it is a newbie question, but why are we not including direct fire RIMS in the discussion?

Click to expand...

Well, he did say electric in the title.

Boerderij_Kabouter said:

HERMS:


Cons
•mostly useless for step mashes or adjusting mash temp, unless you use a vessel other than HLT or overshoot sparge temps

Click to expand...

NOT arguing... just saying that I do just what you've suggested and use a third vessel... my boil kettle for my HERMS system.

I heat my HLT to a few degrees over my mash temp and then heat my boil kettle to my strike temp (plus a couple degrees for loss in transfer).

To mash in, I fill the MT from the BK and then just circ through the HLT.

If I want to do steps, I simple shut off the circ through the HLT for a few minutes, bring the temp up in the HLT... I do a small infusion from the BK and then circ through the HLT to finish off the step. It can be done very quickly (five minutes) if done right and you don't end up with a million gallons in the MT.

I think adjustments are easy on my HERMS... too low I just bump up temp in my HLT and for small adjustments it doesn't take long. For big adjustments, again, I'll just do a small infusion along with raising the temp in the HLT.

For downward adjustments... that's easy... jsut add a small amount of cold water to the HLT and it'll drop the mash temp quickly.

Bobby_M said:

There really is no particular reason. I guess it's because I already use a direct fire RIMS (manual mode) so I was thinking towards the future and picked the two most common alternatives. I'll start.

Direct Fire RIMS:
Pro:
Shortest recirculation path (little to no impact though).
Fastest heat steps.

Con:
Stuck recirculation for too long will scorch, no question.
Automating harder than electric options (pilot lights, etc).
Requires full false bottom to keep thick mash off heatable surface.
Requires heat resistant insulation on tun.

Click to expand...

Okay, newbie help here...So, if I were to have this sort of set up (http://www.brew-magic.com/rims_brwy_classic.html) and wanted to do step mashes manually, my biggests risks would be that the recirculating wort could become a stuck mash and cause scorching? (how often does this happen if you have a good false bottom?) Is heat resistant insulation absolutely necessary (couldn't you just keep your burner turned on low enough to maintain the temps)? Would the above system work well without any modifications if I'm interested in doing step mashes in the future?