HLT / MLT temp disparity

Squid · Joined: 09 Apr 2016 Posts: 33

Hello all,
Just wondering what temp difference they are getting between their HLT and MLT when recirculating. I have to run the HLT 15 deg hotter than desired MLT temp typically. I'm only asking because I saw a pic of Kal's setup and the temp readout for HLT was the same as MLT which I find extraordinary.

Edit: Realised as I hit submit that this is probably the forum section to post it in. Sorry.

**kal** · Posted: Sun Jan 15, 2017 6:09 pm Post subject:

15 is high (I'm assuming fahrenheit). Many have 2-3 degrees difference. Make sure to calibrate both MLT and HLT temp probes in a cut of warm water at around mash temp (150-160F) first using a known accurate thermometer like the ThermaPen.

Can you tell us more about your setup?

Was the 15 degrees when testing with water or when brewing? If brewing it could be you have flow issues.

The temperature differential question comes up a lot. Here are some previous threads about it with hints to look for to try and figure out why you have such a large difference:

http://www.theelectricbrewery.com/forum/viewtopic.php?t=25474
http://www.theelectricbrewery.com/forum/viewtopic.php?t=26408
http://www.theelectricbrewery.com/forum/viewtopic.php?t=28283
http://www.theelectricbrewery.com/forum/viewtopic.php?t=25474
http://www.theelectricbrewery.com/forum/viewtopic.php?t=30387
http://www.theelectricbrewery.com/forum/viewtopic.php?t=26722

Give them a read and please post back here if you have any questions.

Things people will want to know:

- What kettles / false bottom you use
- Mill gap setting / grist composition during this 15 degree difference
- What the ambient temp is when you brew
- Hose types and wall thickness
- Hose lengths
- How fast you recirc (I run two March 809 pumps both 100% open)
- Where your temp probes are
- Any other differences to your setup

Good luck!

Kal

Master · Posted: Sun Jan 15, 2017 7:09 pm Post subject:

I have a 3-4F degree difference once steady state. 15m of 12mm tubing in the HERMS coil.

I normally have my strike water in the MLT, Have the HLT to about 1" above the coils, and as the system is heating (HLT and MLT both circulating) I lag about 12-13F during heat up, and then have about 3-4 degree delta once up and mashed in.

As my MLT is a Keggle with a less than optimal false bottom, I mash in with good flow, and about 15-20 minutes in with a normal grain bill, say 10-11 pounds of nothing too gummy, it will start to lose heat, and it's usually due to flow issues.

I give the false bottom a scraping with the mash paddle, and it comes right back to the 3-4 degree delta in short notice.

For the Stout I brewed yesterday, I had the following grain bill:
9 lbs Pale Ale Malt 2-Row (Briess) (3.5 SRM) Grain 1 70.6 %
1 lbs Caramel Malt - 20L (Briess) (20.0 SRM) Grain 2 7.8 %
12.0 oz Caramel Malt - 60L (Briess) (60.0 SRM) Grain 3 5.9 %
12.0 oz Munich 20L (Briess) (20.0 SRM) Grain 4 5.9 %
12.0 oz Roasted Barley (Briess) (300.0 SRM) Grain 5 5.9 %
8.0 oz Black (Patent) Malt (500.0 SRM) Grain 6 3.9 %

My mash profile was a single infusion, 60 minutes.
Using the infusion calculator in BeerSmith, I took the total water volume in the HLT (10g) and MLT + HERMS (5g) and figured out the correct total temp to hit my 156 Mash Temp.. Worked out to about 160.

I set the HLT control to 164, and when the MLT hit 160, I reset the HLT PID to 160 and then mashed in. Restarted circulation, temp settled in at 155, and it flowed well.. About 15 minutes in, I saw it go from 156 and slowly start dropping 155, 154.. I then get out of my chair, Stir the mash some, note that it is "gummy" and make sure I scrape the false bottom.. As I'm doing that, I can see the flow rate pick right up again, and within a minute it's back at 156.

As the mash continues, it hits "max gummyness" at about 30-35 minutes, which is about when the bulk of the starch is in the water, but hasn't finished breaking down all the way yet. At about the 45 minute mark, it gets noticeably clearer, and thinner, and at this point, I give the grain bed one last big stir, and then basically have the last 15 minutes plus the mash out be the "vorlauf".

When it's 60 minutes in to the mash, I increase the HLT control to 172 for my 168 mashout.. Once the MLT gets to 168, I hold that for 15 minutes, then reconfigure for the sparge/transfer to Boil Kettle.

At about 10 minutes into the mashout, I reset the HLT element for 168 for sparge.

Each system is going to be slightly different due to environmentals, etc.

On a warm day, my temp difference may be only 2.. And the having to scrape the false bottom is basically due to me being cheap and recycling a Keggle to save money. The Blichmann or SS False Bottoms probably won't have that problem.

Squid · Joined: 09 Apr 2016 Posts: 33

Gentlemen - thanks for the replies. I think both of you have made very applicable points in that I too am using a keggle with sketchy false bottom. and am having flow issues, such that all my hoses kink just after the quick release fitting and often the pump sucks the kinked portion flat. New thicker walled hoses have been ordered so hopefully that cures most of it. As far as stirring the mash - interesting as I always thought to leave it be after the initial stirring.

Just calibrated the probes and found them within 1 deg of the thermopen.

JeffW · Joined: 19 Jan 2020 Posts: 19

Going to move my MLT/HLT temp lag issue from my first post to jump onto another thread instead of starting an additional thread with the same issue. I have a 2-3 degree temp difference between the two.

Setup:
15 gal Blichmann
March pumps 115v (809-ss-hs-c)
Tubing is silicone (1/2" ID, part # 92-4389A from AIH)

Will attach a couple photos if I can figure it out.

My first brew day the MLT never got up to HLT temp (lagged by 2-3 degrees). Grain was milled at 0.045.

I tried with just water and had the same issue. HLT heats up ok (set to 152), MLT is circulating through HERMS, but temp in MLT never gets above 149/150 (gave it an hour and it maxed out at 150, barely). I confirmed that the temp probes were reading accurately with my Thermapen. Heating elements are getting 240V.

I could shorten my hoses by a small amount (maybe 6-8"), but from reading the other threads about this issue, I suspect this won't result in a fix.

I could increase the temp of the HLT by a few degrees to correct, but I would prefer to fix the problem, if possible.

Appreciate any suggestions.

Thank you!

**kal** · Posted: Fri Sep 18, 2020 1:05 am Post subject:

JeffW · Joined: 19 Jan 2020 Posts: 19

Hi, apologies for not replying to your previous response. I found your suggestions very helpful in the troubleshooting process. I worked my way through the threads you listed and, after some rearranging, still wasn't quite able to figure out the temp lag issue. This time around, I tried to include all of the information relevant to my setup, plus a couple photos.

The only thing I haven't done yet is re-check all of the PID settings on the control panel. Given that the temperature probes seem to be reading accurately (according to my Thermapen), I figured there was an issue I was missing somewhere in the setup/transfer. I will verify the PID settings and try the run again with water. I'll also go through the threads you suggested once more to make sure I didn't miss anything obvious.

Thanks! Greatly appreciate the help. Will let you know if I'm able to figure it out.

**kal** · Posted: Fri Sep 18, 2020 12:14 pm Post subject:

JeffW · Joined: 19 Jan 2020 Posts: 19

OD of my hose is 3/4" and both pumps are running full open.

Checked my PIDs today and they were all messed up. I thought for sure that would fix the problem, but I still have a 2 degree delta - seems very consistent, at least. Easy fix by just increasing the HLT by 2, but still very annoying. If it bothers me enough, maybe I'll try some 7/8" OD hose.

Appreciate the suggestions. Will update if I find the problem.

BTW: the Ruthess Rye clone was outstanding! Brewing the blonde ale tomorrow.

**kal** · Posted: Fri Sep 18, 2020 10:36 pm Post subject:

I would reset the PIDs to the defaults and use what's recommended here:

http://www.theelectricbrewery.com/control-panel-setup

Cheers!

P.S. Glad you enjoyed the Ruthless Rye!

Kal