Breaking in HERMS system

[Zgreens]

Hi Homebrewtalk! I did my first brew on my HERMS system on Saturday, and I have an issue that I've been pondering. I used a ToP to sense the temperature of the sweet wort returning to the mash tun. I struck the grains to my mash temp of 152, and set the ToP to 151. After about 10 minutes of circulating, my mash had dropped to 140! I adjusted the temp of my returning wort all the way up to 168 (the highest I dared). And the temp only climbed to 144 by the end if the mash. I would have kept going, but it seemed to me that I got decent conversion. The wort tasted sweet, and my refractometer read 1.086 for my first runnings. (Target Og 1.072). I calculate 70% efficiency.
I cannot figure out where I went wrong. In my mind, 47 lbs of grain and 15 gallons of strike water should not be capable of losing a degree per minute under constant recirc. I am wondering if you guys could help me troubleshoot.

 

[atoughram]

Pardon my ignorance.... What do you mean by ToP?

 

[poptarts]

sounds like your a recicurlating too slow. 15 gallons and 47lbs of grain is a hell of alot of thermal mass that needs to be heated it will take alot of energy.

 

[ryan_george]

I agree with poptarts. Also, your big pots (steel? aluminum?) are massive heat sinks and you are losing a lot of heat to the surroundings. I'd highly suggest wrapping your MLT in some sort of insulation to retain that heat.

 

[Zgreens]

I was full bore with the pumps, pots are stainless. I thought that because of the large thermal mass, that they would only be trying to drop a few degrees over the hour... Higher volume to surface area and all that.

Sounds like you guys are right. I'll hit it with reflectix, and see if that helps. Should I have my temp probe in the circulation post HEX, or in my HLT do you think?

Any thoughts about the fact that I have 73% pre boil efficiency with what was presumably a seriously under temp mash? Both thermometers agree with each other in a water bath.

Thanks for the advise!

 

[poptarts]

I put mine on the output of the hex right before the wort enters the mlt.

 

[Zgreens]

Ok, that's where I had it... I guess it just wasn't enough heat output to account for the loss.

 

[ellijo89]

So maybe I misread this but you wanted to mash at 152, but your strike temp was also 152 correct? If so I think it makes sense that your mash temp dropped to 140's and struggled to catch up. Your burner had to heat 15 gallons of strike water, 47 lbs of grain, and lets say 15 gallons of water in HLT? That is a lot of mass to heat up. With my system I calculate my strike temp by putting the strike water amount as my total water in mash, and total water in HLT combined. That way after a few minutes of recirculating I hit almost exactly my mash temp once everything hits equilibrium. Hopefully I understood your post correctly about your strike temp, if not ignore all I wrote!

 

[Zgreens]

Let me clarify: I put 14.5 gallons in my mash tun, heated it to 164 degrees (or thereabouts, don't have my notes), and mashed in. My HLT was at 152, recirculating the water. Upon starting recirc, my ToP started reading about 144, and my mash temp dropped significantly while my HLT heated to about 162 to compensate. Maybe I just need to know the differential between my mash temp and hlt temp, and shoot for it in my hlt at mash-in? Also I suppose expecting the mash to be the same temp as the HEX output is a big assumption...

 

[inkedfireman]

I'm facing the same thing. BrewSmith predicted that I needed a mid-160's HLT temp to hit my mash temp of 150 with 30.5# of grain at 65F in a 15 gallon Sanke. When I mashed in, I was in the low 140's, took me about 45 minutes to get up to 150, but to be fair I had to refill the HLT and get it up to temp. I'm looking forward to the control panel that I can run two elements on, so that I can get the initial mash liquor up to temp in the BK and have the HLT up to temp for the HERMS coil.

Good luck!

Denny

 

[sandyeggoxj]

I only have a 30 amp feed into my panel right now so I can only run 1 5500watt element at a time. I put 10ish gallons of water into my BK and heat it to about 170 or so, depending on the mash temp of the beer I am brewing. Once that is warm I switch the heat to the HLT. That goes to 164-168 depending on my desired strike temperature. Once I pump my strike water over to the MLT I dough-in. I give it a good mix and then cover it. Then I pump my pre-heated water back into my HLT to cover the herms coil. In my kettle that takes 21 gallons. I then move onto my mash process in the BCS. That will heat the water with a PID controlled output back to my mash temperature. If I want to mash at 150 I heat the HLT to 153 or so. It will be higher with lower ambient temperatures and vice versa.

One thing I didn't see above was the diameter and length of your HERMS coil. It would be good to know the metal too.

It has taken me several batches to figure out how to run the system so that I hit, and maintain,my mash temperatures. I undershot them several times. I can now run a batch and mash at 156 +- .5 degrees every time. Even with a BCS it is not as "automated" as I expected. I do love my BCS controller though. I would only replace it with a true PLC with touchscreen HMI. Much like the panels that brewmation produces.