HERMS, Fermentability, and mash temps

I've done quite a bit of searching, but I figured I would start a new thread on this.

What is everyone's thoughts on fermentability of recirculated mashing, and more importantly how your mashout effects it?

Related to my setup: prior to building my HERMS, I just did infusion mashing in a insulated igloo cooler, and that worked great. A 1.055 beer fermented with say WLP001 would attenuate as follows: 148mash ~ 1.009, 152mash ~ 1.011, 155mash ~ 1.014. I always batch sparged, and used the first batch sparge as my mashout( heated the sparge water enough to raise the grain bed to 168). Now I realize with this approach my first runnings were still converting.

With my new HERMS, my attenuation has sucked. I've verified my new RTD therometer with the known good one I used to use. I've also verified the temp of the mash using my known good thermometer. I've mashed batches at 151-152, and 1.055 beers fermented with WLP001 are finishing at like 1.015-1.016. This has happened for three batches in a row, so i'm obviously creating less fermentable wort.

My Process:
Strike at my desired mash temp, or a degree or two less.
Recirculate for the length of the mash, HERMS controls the temp.
Start a 15min ramp to mashout temp of 168*
Begin fly sparging, sparge water at exactly 168*


Now my belief is since I have a 15min ramp to mash-out temps, my wort spends enough time in the alpha amalyse temp range(155+) to create a good amount of unfermentable dextrins. So where do I go forward from here? I like to mash thin, so doing a dedicated mash-out really isn't practical, and I'd really like to continue fly sparging. My two thoughts are:

A. If my intended mash temp with my old system is: 152*. Recirculate at around 148* for 60min, then do my 15min ramp to mash out. I feel like the lower rest will offset the dextrins created in the 155+ range.

B. If my intended mash temp with my old system is: 152*. Recirculate at 152* for 60min. Skip the ramp to mash out, just start sparging with 168* sparge water.


What are your thoughts on this? Anyone else running into similar issues, and if so, what have you done to fix it?

Recirculating the mash makes the temperature more even in the mash process, this basically is great if you expect it. Going from a non-recirculating system however means that you did have a heat dynamo going and most likely (in fact I can guarantee it) different temps depending on where you took your reading. I would try (if you want to get the most fermentable wort) to recirculate with 146-148 for about an hour. That will hold the temp steady at 146-148 and not have you get the 148 in some parts of the cooler and 152 in others.

Oh, I know all about temp stratification, but I don't think that's really the problem here. I did have a little bit when I did infusion mashes, but it was never more than a degree either way

I'll bite. I dove head first into AG with a HERMS, so I know no other way. I have a very similar procedure to yours. However, I have the opposite problem and seem to now be getting TOO low of FG (I am always at 80-85% efficency). My pumpkin ale ended up at 1.004 with 001. My pliny just ended up at 1.008 with 05. I actually don't mind, I prefer dry beers, but the pumpkin I at least wanted at 1.014.

I assume you are using a false bottom. I usually recirculate during the mashout and ramp up to temp also. I have however thought about turning off recirculation, and raising the HTL to about (174 -- what I need to get to 168 grain bed), and then recirculating. I am hoping that this would cause the grian bed to raise temperature much faster without slowly raising the entire time during recirculation.

By mash out, the grain bed is usually so compacted that I feel I could run almost wide open valves to recirculate without messing up the filtering of the grain bed, and therefore go from 150 to 168 in a few minutes.

"Start a 15min ramp to mashout temp of 168*
Begin fly sparging, sparge water at exactly 168*"

I just realized, I set my HTL to 174-176, so then my sparge water is a couple degrees too hot technically-- (I have about a 3-4degree temp loss coming out sparge hose) but I don't have any issues with it. I also do about a 1 hour sparge.

Thoughts?

I like your idea ramping the temp in the HLT, then running the valves wide open. I might try that next time before I make any other drastic changes to my process. I'd bet I can probably flow at least 3-4 gallons/min at wide open, and I'd bet that would raise a mash up in just a couple minutes.

As for your beer finishing at 1.004, unless you had a severe amount of adjuncts in that beer, I'd bet you picked up a wild yeast, or a bug somewhere. I've never had WLP001 attenuate that well. That's like 3711 territory.

Wow -- it's interesting you post this. I just realized this myself with my HERMS -- the slow ramp-up to mash-out temps is definitely doing something to my fermentability profile. I'm using Safale-05, ferment 62F for 7-10 days, and then slowly ramp up to 70F for another two weeks or so -- but I'm usually getting only 68-70% attenuation. I always primary for 2-3 weeks, never use a secondary. This has happened for the past 15-20 brews I've made over the past 6 months. It always amazes me when people talk about > 75% attenuation with Safale-05. I've *never* seen that -- ever. In fact, in the two years I've had my HERMS, I've never hit above 72% with Safale05 -- and have only hit that once or twice. In some cases, I've seen as low as 65%. I'm always slightly higher FG than I'd like. I've been thinking about this for a while, and finally narrowed down to my mash-out ramp-up. I always mash for 90 mins.

If, say, I mash at 152F, it takes 18 mins to ramp my mash temp up to 170 (1 degree per minute with my 5500W heating elements in a 15 gallon HLT). I set my HLT temp to 173F, and this means I get 170F in my MLT-in -- a 2-3 degree differential between my HLT and MLT . So in this case, it's 18 mins to ramp up, then another 10 for mash out.

What I did last weekend was simply ramp up to 168 (from 148 to 168 in the case of a dry Irish stout I was making) -- and then start sparging. No mash out. I'm hoping this shortened mash out -- skipping it essentially, and simply replacing it with my usual 45-min fly-sparge -- will increase my attenuation. Still -- that ramp was 18-20 mins, so that might still impact me. The stout's only 4 days into fermenting -- and is hovering around 1.020 -- so it still needs to drop to 1.012-1.013 (from 1.051) to see if it worked. (It'd be nice to get it within the style's 1.007-1.012 recommendation, but I doubt that will happen given my OG.) I'll take 73% attenuation, though, to 1.013!

If this doesn't, then my Plan B is to skip the ramp-up altogether, start fly-sparging at the end of my 90 min mash, and then ramp up to 170F *as I'm sparging*. (I've done cold sparging before when I was using a cooler, so I suspect I don't need to ramp up at all -- I could probably fly-sparge with my 15xF water since I recirc the entire mash and have no issues with stuck sparges, etc. I'm willing sacrifice a few points of efficiency if I can increase my attenuation. I routinely get 75-85% eff. with my system.)

Don't know. Not sure. But one thing I'm concerned about is losing mouthfeel. My finished beers have been pretty tasty -- good, sturdy mouthfeel -- and all within the finished pH of 4.0 to 4.2. If I lose mouthfeel due to the skipping mashout (which I doubt, but I wonder if the mouthfeel might be a benefit of the slow ramp up and unfermentable sugars in the wort), I may raise my mash pH a bit and see if that helps. (Current mash pH at room temp is anywhere from 5.3 to 5.4 -- although I suspect I could go to 5.5 and still have good, full flavors. Obviously, anything beyond 5.5 will probably not be good -- and will be back to my cooler days when I was using FiveStar 5.2 instead of adjusting pH, but it's something to watch and figure out, I guess.)

It's interesting. I love my HERMS and can't imagine brewing without it, but the slow temp ramps and their impact on fermentability is a thing I've not really seen written about before. I know I can't really do a step mash due to the slow ramps, but I can't recall reading anything about the impact of fermentability due to the slow ramps to mash out. This may mean that it's not an issue -- and this is a red herring -- I don't know. But it's something that's been bugging me about my process. I have three thermometers to monitor mash -- two digital, one analog (one in my HLT, one at my HEX-out, and one in my MLT-in) -- so I know my temps are spot-on and I'm not mistakenly mashing at a higher temp than I think.

bobby: That's exactly the kind of feedback I was looking for!

This hypothosis struck me when I was doing some reading about alpha and beta amalyse, and remembered that alpha works much quicker than beta, usually only needing about 15-20 minutes. I realized that's how much time it took me to ramp to mash out temps, and during that ramp I was in the temp range that alpha is active the entire time.

I've ruled out nearly everything else because nothing else in my process changed other than recirculating, and fly-sparging, I'm even using the same mash tun, same manifold, and the same boil kettle.

I think i'm going to try option B next time I brew. Mash at my intended temp, stop recirculating for a few minutes to raise the temp of my HEX to 170, then just begin sparging 170* water on top of the 15x mash. Plenty of the still-converting wort will drain out well before the temp of the mash is raised enough to matter. Asuming I can hold my typical 82% efficency with that method, and attenuation goes back up, I'll probably stick with that.

The other viable option was what trent recommended. Stop recirculating, raise the temp of the HEX, then recirculate on full blast to very quickly raise the mash temp. I'm working with 5gal batches, so I could probably step up temps fairly quickly if I run the pump as fast as I can get away with.

I might try that tomorrow -- stopping recirc, letting the mash sit while the HLT temp rises, and then start the sparge with 170F water from the HLT.

My only concern is that my MLT is not insulated, so that 20 mins (or thereabouts) that I spend raising the temp on the HLT will mean the mash will steadily lose a few degrees -- not much, I suspect -- but it'll definitely be a drop. Although -- thinking back to my original dilemma of not getting the attenuation I want -- this drop certainly won't hurt anything in that regard.

Great thread. I suspect there are more RIMS users out there than HERMS, but I always like reading about HERMS issues. As I say, I've been brewing with my electric HERMS for 2 years, and it's awesome (both the electric part and the HERMS part)!

I think the same issue applies with RIMS or HERMS. My HERMS started off as a RIMS. I scorched a batch when the mash stuck, then built a HERMS HEX right after. My HERMS coil sits in a separate 2gallon HEX, so I can heat my HEX from 15x to 170 in about 2-3 minutes if i'm not circulating. Same benefit with RIMS, you can transition from re-circulating to sparging much quicker.

My MLT is the same igloo cooler I used when I did infusion mashing, so ya, I didn't think about the possible temp drop while heating the HLT because it isn't an issue for me. Your HLT should heat up much quicker though if you aren't re-circulating through it. If your mash out takes 18min normally, I'll bet you can get your HLT to 168 in about 10 minutes.

I forgot to comment on the mouthfeel thing too. Your mouthfeel will take a little bit of a hit, you're going to lose some of those dextrins, but that's the compromise for a drier beer. I think you can have a beer with good mouthfeel and it still be dry, but the drier beers are much more drinkable.

I will also be trying my idea the next time around. As for the 1.004 I had with 001, it was with a pumpkin beer, and to me, I cannot taste infection or anything else with the beer. I was also puzzled, but it just came out very dry tasting -- nothing bad!

I brewed an amber yesterday and did what Scottland suggested: shutting off recirc after the mash (90mins), cranking the HLT to 173F (for 170 at the MLT-in), and then immediately started fly-sparging (for my usual 45 minutes).

Temp in the MLT dropped only a couple degrees during the recirc cutoff (took about 20 mins to go from 150 to 173F), and my efficiency stayed pretty much the same: 78%.

So I'm happy with the process, but now I'll wait and see if this changes the fermentability profile and increases attenuation a bit. The other good thing was that seemed to cut my brewday down by 20 mins or so -- a nice bonus. Normally, it takes me 7 hours or so -- including all clean-up (running OxyClean free through all the pumps and hoses for 20-30 mins at the very end)-- so anything that cuts off time is a plus.

bobbytuck said:

I brewed an amber yesterday and did what Scottland suggested: shutting off recirc after the mash (90mins), cranking the HLT to 173F (for 170 at the MLT-in), and then immediately started fly-sparging (for my usual 45 minutes).

Temp in the MLT dropped only a couple degrees during the recirc cutoff (took about 20 mins to go from 150 to 173F), and my efficiency stayed pretty much the same: 78%.

So I'm happy with the process, but now I'll wait and see if this changes the fermentability profile and increases attenuation a bit. The other good thing was that seemed to cut my brewday down by 20 mins or so -- a nice bonus. Normally, it takes me 7 hours or so -- including all clean-up (running OxyClean free through all the pumps and hoses for 20-30 mins at the very end)-- so anything that cuts off time is a plus.

Click to expand...

I did a very similar today. 45 minutes into the mash (150) I turned off recirc. At that point I pumped my HLT to 173. After the HLT was at temp, about 20 minutes, I started to recirculate.

Too efficient. The HTL (120V 1500watt) could not keep up, and its temp dropped to about 168 in the tank, and the grain bed stalled out around 162. I had to just keep recirculating anyway to get the grain bed up to 168. Maybe next time I will not try a "mash out", but just sparge with the 170 water like you do.

Update:

I double checked my thermometers, and also bought a second RTD to take temps at the mash tun exit. My two RTDs and one dial thermometer all read within 1* of each other at both 32* and 210*(boiling here). Armed with accurate temp probes, I'm finding that the temp exiting the herms coil is only 1-2* higher than the temp measured exiting the mash tun. I'm perfectly happy with that considering I'll lose a little heat on the way to the mash tun, and the fittings at the exit of the mash tun will lose a little heat as well.

I brewed a pumpkin ale last weekend. 1lb of Crystal in the grain bill. Mashed at 151* for 60min. After a full 60min of recirculating, I killed the pump, and let the heat rise in my HERMS HEX to 168*. Then I began sparging 168* sparge water on top of the 151* mash. It took about 5-10min before the exit temp on the MLT went up a single degree. At the end of the sparge my exiting wort was 165*.

OG came in at 1.055, I anticipated this to finish around 1.012 to 1.013 (Safale US-05). Fermented at 64*, then raised the temp to 68* on the 4th day (my normal procedure with US-05). Now on day 8 we're at about 1.014, which is a definitely improvement over my last couple beers, but still not quite where I want it to be. Hopefully it will drop one more point, and I'll be back where I expect.

I can't believe I forgot about this, but my hydrometer broke right around the time I built my RIMS/HERMS system. I finally realized I never checked the new one with pure water. Sure enough, it reads 1-1.5 points high.

So that combined with my new sparge technique seems to have fixed the problem. My latest beer finished at 1.012-1.013 which is exactly where I expected it to finish. Whew, I feel much better now.

Update:

In retrospect, this is not especially shocking, but since I've skipped the slow temp rise to mash-out, shutting off re circulation from HLT to MLT to prepare for the sparge (thereby letting the HLT rise on its own from mash temp to 173F for the sparge and skipped the mashout altogether) my attenuation levels have been fantastic.

I just brewed an Amber Ale that went from 1.061 to 1.014 in five days with Safale-05 -- the first time I've gotten over 74% attenuation on my system with Safale-05 (fermenting at 62F for all five days no less!).

So I'm realizing that HERMS is not great for stepping up temps (if you're looking for attenuation). The ramp-up for most HERMS systems *with recirculation* is pretty slow and is obviously introducing a lot of unfermentables going from mash temp to mash out. I've been doing this slow ramp-up to mash out for over a year -- well over 35+ brews -- so I'm glad I finally figured this out. I thought it was something I was doing during fermentation or even with the boil (even though my eHERMS has a wicked vigorous boil and can easily boil off 1.5 gallons an hour if I don't adjust it down slightly) -- but this idea of skipping the mashout and going directly to the sparge never dawned on me. My efficiencies are still in the mid-70's to mid-80's -- so skipping the mashout didn't impact that too much.

I brew outside in Chicago (on a TopTier), so my brew season is slowly coming to an end -- maybe another month or so into mid-November -- and then I'll pack it in for the winter. But it's definitely going to change my last few brews -- and definitely something I'll look forward to tweaking even more in the coming spring.

Between my experiments with pH control and now figuring out my attenuation issues, it's been a pretty kickass brew season!

Bobby, i'm right there with you, I can't tell you how excited I am that we figured this out.

Gents-

My rig:

20g insulated mash tun
26g boil kettle
3.6g 240VAC 5500w heat exchanger (cut down corney keg)
T-type thermocouple

I get about 3f temp rise over 90-120 seconds when recirculating. If I mash in at 140 and raise 2 degrees every 10 minutes to 162 I get a FG of about 1.009 with Nottingham. It's my favorite yeast. The grist is 90% pale, 4% rice and 6% crystal 10 roughly...

Changing the heat exchanger and being able to effect rapid temp changes was key to ultra low finishing gravity beers. Lawnmower Lager (17lbs pilsner & 5lbs rice) finishes at 1.006 and (if you use a good hop schedule) quite tasty if you happen to be serving lightweights. If you ferment that using nottingham at 62 it tastes just like a lager.

It's also a COOL thing to experiment, doing SMaSH Ales (Single Malt and Singl Hop) and changing only the hop to get a feel for how they taste in a beer that has little malt character...

bobbytuck said:

Update:

In retrospect, this is not especially shocking, but since I've skipped the slow temp rise to mash-out, shutting off re circulation from HLT to MLT to prepare for the sparge (thereby letting the HLT rise on its own from mash temp to 173F for the sparge and skipped the mashout altogether) my attenuation levels have been fantastic.

I just brewed an Amber Ale that went from 1.061 to 1.014 in five days with Safale-05 -- the first time I've gotten over 74% attenuation on my system with Safale-05 (fermenting at 62F for all five days no less!).

So I'm realizing that HERMS is not great for stepping up temps (if you're looking for attenuation). The ramp-up for most HERMS systems *with recirculation* is pretty slow and is obviously introducing a lot of unfermentables going from mash temp to mash out. I've been doing this slow ramp-up to mash out for over a year -- well over 35+ brews -- so I'm glad I finally figured this out. I thought it was something I was doing during fermentation or even with the boil (even though my eHERMS has a wicked vigorous boil and can easily boil off 1.5 gallons an hour if I don't adjust it down slightly) -- but this idea of skipping the mashout and going directly to the sparge never dawned on me. My efficiencies are still in the mid-70's to mid-80's -- so skipping the mashout didn't impact that too much.

I brew outside in Chicago (on a TopTier), so my brew season is slowly coming to an end -- maybe another month or so into mid-November -- and then I'll pack it in for the winter. But it's definitely going to change my last few brews -- and definitely something I'll look forward to tweaking even more in the coming spring.

Between my experiments with pH control and now figuring out my attenuation issues, it's been a pretty kickass brew season!

Click to expand...

ok kicking an old thread but saw this on my first HERMS brew

this is the same probelm i had
have you tweek the process further????

I stopped doing a mash out, and that fixed the problem for me. It's been like 14months, roughly 30 batches, and zero problems.

I recirculate at my mash temp for 55min. Then I shut off the pump, and allow my HEX to rise in temp in anticipation for the hot sparge water. After 5min, I start sparging with 170* water without a mash out. It's worked great

Very nice Scottland;

Another thing to consider though is that the BIGGEST benefit you get out of HERMS is that the amylase is in suspension with the wort, and the point of highest heat ( exit of the heat exchanger) is the conversion point of the enzymatic activity. Being able to recirculate at wide open throttle has been a big benefit for my rig, as it raises the temp inside my mlt pretty quickly too allowing conversion to continue in there.

Another benefit, I don't bother milling dark grains (like 80+srm) I just dump them on top of the grain bed...crushing them tends to make a dusty mess and I get all the flavor out if it like this w/o the hassle....

Great Scotts!

thanks for the quick response now to brew better beer
prost!

I could never get consistent attenuation out of 05. I would make 15 gallon batches and split the wort into 3 different primaries. I would pitch them all with 05 and put in the ferment freezer. I wouldn't get the same attenuation. Never used Nottingham, but have been thinking of using it for my summer beer for ease. When I built my HERMS I ran into some attenuation problems. I figured in part that it was my thin mashing. I thought I needed to be thin to recirc my mash. I now mash at about 1.38 qts/lb and mash in starting with a Beta rest around 145-148 for 30 min. I raise the temp for an Alpha rest at around 156-158 for 30 min and then raise slowly to mashout temp. I added a tee to the cooler drain so I can recirc at full open and trickle to the kettle during my sparge of 60 min. I use 007 for most of my IPA/dry beers and I usually get 78-80% attenuation. I think when using a HERMS the key is really paying attention to your own system. Design, temp loss, speed of temp rise, makes the results a bit different. I'm not sure that the HERMS is what made my beers improve so much. I think it had more to do with learning to build the water and paying close attention the the mash ph. I do like having the ability to change temps. For some reason, it makes me enjoy the brew day a bit more.

very interesting.....
I thought HERMS would be the savior, what it did was add to the complexity of the brew day.

i just gotta brew more and learn the system as suggested