Help with Mash step, full volume herms.

[marjen]

So I am coming from the world of BIAB. I just setup a new electric brewing system and had my first pre day. I had a huge issue with my wort.

So I am using a 2 vessel + external herms setup. Using an exhilarator as my herms coil. I got everything up to temp, strike was set to about 160 f. I verified temp in the Mash tun by using a hand held thermometer. Put my grains in. Was 11 lb total. Pre boil gravity should have been 1.040, it ended up being only 1.024. I didn't realize this until I had sent it over to the boil kettle. So I actually transfered all the wort back and tried to let it go another 30 mins. No change in gravity.

A couple notes.

1. When I mashed in I kept the pumps and coil running. I watched a video from spike on their website and noticed they mashed right in with the mash tun recirculating. But I have seen others say you need to stop pumps to set a grain bed? Not sure which is correct or if either is wrong.

2. I did have 4.5 lb of questionable grains. I used some old 2-row. It has been stored in 5 gallon sealed bucket, but last year it was stored in a non climate controlled storage shed as we built a new house. SO I am sure it got quite hot in there over the summer. Additionally the grain was from early 2017. SO not sure if it was just bad. If I remove this from the recipe it says pre boil would be 1.024 which is exactly what I got.

Anyway hoping to get some feedback before the next brew day. Making sure I have new 2-row so I can eliminate that from the suspect list and I guess will see what happens.

 

[RM-MN]

2. I did have 4.5 lb of questionable grains. I used some old 2-row. It has been stored in 5 gallon sealed bucket, but last year it was stored in a non climate controlled storage shed as we built a new house. SO I am sure it got quite hot in there over the summer. Additionally the grain was from early 2017. SO not sure if it was just bad. If I remove this from the recipe it says pre boil would be 1.024 which is exactly what I got.

Even if the grains were old and had no diastatic power there should have been plenty of enzymes from the rest of the grain to convert the starches. I don't think the age of this grain is the problem.

 

[marjen]

When recirculating the mash through the coil should it be on the slow side like a trickle or a fairly steady to fast speed?

 

[day_trippr]

I recirculate as fast as the grain bed allows as that allows the smallest hlt vs mash temperature differential. I usually run my hlt 1.5°F over the target mash temperature while recirculating between 2 and 3 gallons per minute.

Generally, the slower the recirculation the hotter the hex exit temperature needed to counter mlt and plumbing thermal losses (which are pretty much fixed). At the low flow/high exit temperature extreme one may risk denaturing the enzymes necessary to fully convert the mash. High flow/lower exit temperature is less stressful in that respect...

Cheers!

 

[Bobby_M]

Shut recirc off while stirring the grains in, then start back up very slowly and then increase to about a quart per minute. If you're going to keep that CFC hex design, I recommend putting the controller's probe in a tee directly on the heat exchanger's wort output. Also change the controller cycle time to 1 second.

 

[marjen]

Shut recirc off while stirring the grains in, then start back up very slowly and then increase to about a quart per minute. If you're going to keep that CFC hex design, I recommend putting the controller's probe in a tee directly on the heat exchanger's wort output. Also change the controller cycle time to 1 second.

I currently have a T off the out on the boil kettle and the Brewcommander temp probe is on that tee. It then goes from there to pump to wort out on the exchanger. I am then using a hand held thermometer to check mash tun temp. I will look at playing with cycle time.

 

[acidrain]

After striking in at 160F, what was the actual mash temp?
It sounds like maybe (since your recirculating during strike) that the mash did not drop to the target mash temp, and that maybe some of the the enzymes were denatured or created sugars that are less fermentable.
Just checking... did the mash hit and hold at the target temp? What was the target temp?
Is your thermometer calibrated?

 

[Bobby_M]

I currently have a T off the out on the boil kettle and the Brewcommander temp probe is on that tee. It then goes from there to pump to wort out on the exchanger. I am then using a hand held thermometer to check mash tun temp. I will look at playing with cycle time.

That's not a great place for it. You probably overheated your mash. Whenever you target a new temp that is higher than the actual mash, your heat is going to come on for a long time and the wort coming out of the CFC is going to be potentially heated over denaturing temps. That heat will only shut off when the BOTTOM of the mash reaches your set point and by then the wort on TOP is going to be too hot.

1. Best place for the probe is on the CFC wort output.
2. Second best place is on the hot water coming out of the HLT before the CFC.

 

[marjen]

I guess this is where I am confused. I am heating the water in the boil kettle. I can tell you that was quite hot. Probably in the 180+ range. Also the temp on the boil out was showing 10-20 higher than mash temp for awhile till it finally caught up. I am only using 4 gallons in the boil kettle so it was getting really hot. I was measuring temps by hand in the mash tun. So I was checking temps on the top which should have been higher than the bottom. I have added a temp sensor on the out of the Mash tun for next brew day.

So even though the water from the BK is really hot I am assuming that it should be and the wort in the mash tun should never really get that high.

 

[day_trippr]

Ideally, one sets the strike volume temperature to account for grain temperature and the mash tun (and false bottom if used) temperature, with both accounting for respective mass, such that after a few minutes and a good stir the mash lands at the desired temperature.

Unless you were using an exceptionally chill mlt and pile of grain I can say with high confidence that if you struck using four gallons at 180°F+ you were wayyyy the heck over any conventional mash temperature. By contrast, my last imperial stout with 44 pounds of grain @66°F in a 20 gallon mlt w/fb averaging 78°F, my prescribed strike temperature was 167.5°F, and the mash stabilized five minutes post-strike at the planned 152°F...

Cheers!

 

[marjen]

Unless you were using an exceptionally chill mlt and pile of grain I can say with high confidence that if you struck using four gallons at 180°F+ you were wayyyy the heck over any conventional mash temperature. By contrast, my last imperial stout with 44 pounds of grain @66°F in a 20 gallon mlt w/fb averaging 78°F, my prescribed strike temperature was 167.5°F, and the mash stabilized five minutes post-strike at the planned 152°F...

Cheers!

Let me try to explain the temps better. The 180+ was temp in the boil kettle near the heating element. I am reading temps on the outflow from the boil kettle, thats where my temp sensor is, the highest that ever ready was 170. The 180+ I got by using a hand thermometer in the boil kettle.

For the wort I was using a handheld thermometer I would read the wort in as it dropped through the top port and the overall temp on top of the wort, that got to a high of 162 strike, then when I mashed in it drop to 156 and I kept around 154 for the hour. So I never saw a super high temp from the wort, just the in the boil kettle.

This time I will be making a couple changes. First all fresh malts to make sure that was not part of the issue. I am using a bag in my MLT and will probably squeeze it out as the mat empties. I am also adding a thermometer to the wort out on the MLT to see what the temp looks like on the bottom of the MLT.

 

[Bobby_M]

That's why I'm suggesting that the temperature controller, that is heating your boil kettle water, is being fed termperature data from the WORT output of the heat exchanger (CFC in your case). This is because your CFC is acting a lot more like a RIMS than a HERMS especially if you only have enough water in your kettle to more or less cover the element. It's more dynamic than a typical HERMS anyway.

Let's say the whole mash is 148F and you really wanted it to be 150. You set the controller to 150. System runs a while... controller is trying to reach 150 so it's going to apply some heat to the water. As the wort output temp climbs closer to 150, it will back off on the heating. Frankly you don't need to care about the temp of the boil kettle water since it doesn't matter. The controller will make it as hot as it needs to be so that the wort leaving the HEX is 150.

Ok so it's running at 150 stable for a while. Now you push a handheld probe into the core of the mash. Wait a minute, that's reading 147F.

THAT is what the RIMS OFFSET setting is for. You enter 3. Now when you set your controller to 150, it will heat the water in the boil kettle hot enough (don't care) to make the wort come out of the HEX at 153 so that it will eventually make the full mash 150F.

Eventually? How long? THAT is what the mash heat rate setting is for. Lets say your mash is rockin at 150F for a while. Now you want to run it up to a mashout. You set the controller to 168F. You can measure your mash ramp rate by leaving that thermometer probe in the core of the mash. Immediately set a timer and measure the time it takes for the core of the mash to go from 150 to 168. Take the time it took and divide it by 18 degrees.

 

[marjen]

@Bobby_M Thanks for the info. I see what you are saying and a lot of it is making sense. I just have a couple followups.

1. Since I only have a 2 ft hose from the HEX Wort out to MT Wort in, could the probe be put on the MT at the wort in connection?
2. I am assuming I don't care how hot the water gets in the boil kettle? Meaning even if its like 190 or something really high, it won't overheat the wort. And again while I was measuring really high temps in the BT near the heating element, I was only seeing 170-175 leaving the boil kettle.
3. If I move the temp sensor I will lose the ability to track temp in the BT. Having only used the brew commander once so far, I assume this is ok because in boil mode its just running at 100% until I manually reduce the % as it nears and gets to boiling. So temp does not really matter because I don't think the BC automatically dials back the % based on hitting 212. correct?

Thanks for your help. Looking to brew tomorrow and incorporate some of these new ideas.

 

[day_trippr]

Is that "24ft" a typo?
I have an 18 inch hose from hex out to malt in...

Cheers!

 

[marjen]

Is that "24ft" a typo?
I have an 18 inch hose from hex out to malt in...

Cheers!

It sure was lol.

 

[Bobby_M]

@Bobby_M Thanks for the info. I see what you are saying and a lot of it is making sense. I just have a couple followups.

1. Since I only have a 2 ft hose from the HEX Wort out to MT Wort in, could the probe be put on the MT at the wort in connection?
2. I am assuming I don't care how hot the water gets in the boil kettle? Meaning even if its like 190 or something really high, it won't overheat the wort. And again while I was measuring really high temps in the BT near the heating element, I was only seeing 170-175 leaving the boil kettle.
3. If I move the temp sensor I will lose the ability to track temp in the BT. Having only used the brew commander once so far, I assume this is ok because in boil mode its just running at 100% until I manually reduce the % as it nears and gets to boiling. So temp does not really matter because I don't think the BC automatically dials back the % based on hitting 212. correct?

Thanks for your help. Looking to brew tomorrow and incorporate some of these new ideas.

1. Correct, you don't want it too far removed from the HEX exit but 24" is nothing.
2. Kind of true. It shouldn't get to 190 unless your CFC is only a few feet long. It will likely only get a few degrees above your desired wort output temp. Make sure you have the cycle time set as low as it can go in the BC advanced menu.
3. The BC doesn't care about the temperature of the probe when it is in boil mode. It won't necessarily display the correct temp but the power output % is set by you manually no matter what.

Keep in mind that all of my comments are based on how I think you'll get the most accurate mash performance and repeatability out of the system that you've built here. In no way am I suggesting this is the best way to brew or even the best way to use a 2 vessel system. I think this is nearing a Rube Goldberg machine. Wanna know how I'd do it?

1. I'd put the temp probe in the boil kettle. I'd put a false bottom over the element and drop a bag in for the grain. Done.

2. If you MUST use two vessels, put the probe in the boil kettle directly. Pump the wort out of the boil kettle drain and into an Autosparge in the mash tun. Pump the mash into the boil kettle via a whirlpool return. Done... That's the Blichmann Breweasy.

Both of these options are easier to dial in.