Scorching issues? w/ 4500W ULWD element?!?

[StrngBrewer]

Long time lurker, first time poster...

I've recently switched my 2 vessel electric system to a single vessel eBIAB. I never had any issues with scorching with my original element (LWD 4500W 240V). But that burned out in the middle of a boil last fall (not sure what happened), so I ran out and just got a replacement at the local hardware store to finish the beer (Surly Darkness clone). Didn't get any time to brew over the winter.

First spring brew day I brewed a 10 gallon batch that I split into an IPA and an Amber Ale, and had terrible scorching issues. I thought it was a mix-up at the LHBS w/ the smoked malt because they both were undrinkable. Next batch, tried a Little Sumpin' Sumpin' clone, same problem. At this point, I started to suspect the cheap-o replacement element, so I ordered a new 304 SS, 4500W, ULWD ripple element and tried again.

During the brew, I went upstairs for 5 minutes during the boil and coming back down caught the very noticeable smokey smell. After transfer to the primary, noticed the milk chocolate colored gunk on the element. And, I just opened the primary to transfer to secondary and it smells like an ash tray.

I've verified supply voltage is within a couple volts of 240V. The element was clean or brand new with all of these. I have a PID controller (Omron E5CK) with on/off control of an SSR only (no PWM), but this has never given me a problem before.

I have no idea what could have changed... or apparently how to fix it. Any ideas?

 

[jeffmeh]

Is the element active under PID control throughout the mash? Are you recirculating during the mash? Are you recirculating or stirring after the mash until the boil is enough to keep particulate matter in suspension? Did you interrupt the boil and restart it?

 

[StrngBrewer]

Is the element active under PID control throughout the mash? Are you recirculating during the mash? Are you recirculating or stirring after the mash until the boil is enough to keep particulate matter in suspension? Did you interrupt the boil and restart it?

To make replies easier, I'm going to refer to:
Brew 1- The old single element, HLT/BK & separate MLT set up.
Brew 2 - the eBIAB set up. Dough in @ 150F.
Brew 3 - same as brew 2 but with new ULWD element. Also didn't want to add acid, so tried to do an acid rest so grain was in bag from 95 F.

Brew 1 didn't recirc because of a severely stuck sparge. Normally would have been recirc'ing once sparge water started to flow.

Brew 2- I recirculated during the mash, but not thru the bag. My thermocouple enters the tank thru the same fitting as the outlet flow, so almost have to in order to get accurate temp. PID active for whole mash & boil (continuous).

Brew 3- recirc thru the bag (thinking it would filter better).

Other stuff:
All 3 had high particulates. Brew 1 due to the crappy lauter. 2&3 due to a grain bill of about 50% wheat. Water/grist ratio was a pretty stiff 2 (for BIAB).

So is scorching only caused by burning particulate on the element?

 

[jeffmeh]

I believe that with a ULWD element scorching would be highly unlikely unless there were particles settling on the element.

Let's just focus on Brew 3, as that is your current setup.

Did you begin recirculating immediately after dough-in? If you are going to recirculate, then definitely do it through the bag for the entire mash.

How coarse or fine is the material for your bag? More coarse allows larger particles to pass through, more fine is more finicky to get a good recirculation. You want to get the maximum flow possible without it getting stuck in the bag.

What kind of pump are you using, where does the recirculation loop exit and enter the kettle, and how are you controlling the pump output?

Another option is to bring your mash water up to temp, dough-in, turn off the element, and throw some insulation over the kettle. But that is giving up, as you should be able to figure out a way to get this to work with recirculation.

 

[StrngBrewer]

Ok, took me a while to gather info...
Bag I bought from here: http://biabbags.webs.com/
It's a pretty fine mesh. I can't comment on whether it's too fine or too coarse or just right since this is the only one I've used.

Recirculation started immediately after dough-in and went through the bag (this time).

Attached a pic of the general setup & view in the kettle. I've got a standard March magnetic pump that I built with a home-made counter flow heat-exchanger into a bucket (based on a BYO build). The outlet of the pump always flows through the 3/8 copper inner tubing coil and I turn on the cooling water when I want to cool. There's a valve that I can use to knock the flow down, but I've never needed to with all that tubing restriction. It enters back into the kettle in the back left and, in theory, flows across the element to get to the outlet. Not shown is the 14.5" grill cover that I bolted some 3" SS legs (ie, 1/4-20 bolts) onto in order to keep the bag off the element.

You can also see that after seven days soaking in PBW I've still got a hefty layer of scorch (granted, I haven't applied any elbow grease to it yet).

The "other option" is essentially what I used to do, except do the mash in the Igloo MLT -- ie, Brew 1. So it seems even giving up might not be an option.

 

[lschiavo]

Not sure if I'm following exactly but it sounds like switching to biab was when the issue started. How are you keeping the bag off the element? Seems like a bag of grain wrapped around an element could be an issue...I don't biab so I may be way off.

 

[StrngBrewer]

lschiavo,
I don't think that's it. Brew 1 was before switching to biab & I've got a converted grill grate to keep the bag off the element

 

[lschiavo]

Sorry, totally missed that in your previous post.

I see your temp probe is on the outlet of your kettle. it seems it could take a while for the temp change to register that way and maybe the pid overshoots.

 

[StrngBrewer]

yeah, it sits inside the outlet Tee so I have to run the pump in order to get an accurate reading & control. I'd like to get a beefier one (so I don't whack it) and get it moved to internal, it's just low on the priority list.

 

[raysmithtx]

I've had one scorching issue with BIAB. I recirculate during the mash and one time the bag slightly clogged. The pump was pumping the water into the bag but it was not draining fast enough to keep the element covered. Some grain ended up on the uncovered element and scorched. I noticed the liquid level getting higher and higher in the kettle and realized what the problem was. Now I make sure I watch the volume level when I have the pump and element on. When I see the volume level going up I stop the pump and stir/scrap the side of the bag until the volume level is back to normal. As added insurance I just turn the element one for about 45 seconds when the temp. drops over 1 degree, then turn it off and stir.

 

[StrngBrewer]

I noticed the liquid level getting higher and higher in the kettle

OH! That reminds me, I did see some weirdness with the liquid level when I first doughed-in on Brew 3. Mine actually went down, but only for a while. It looked like I temporarily lost about 3 gallons for about 10 minutes but I couldn't figure out where it could have gone, what with the conservation of mass law. I'd just assumed it was absorbed into the grain, did it's magic and then came back out.

 

[LarMoeCur]

I don't do BIAB. With my EHERMS setup the pump will run my MLT dry when I do 5 gallon batches. I've got to throttle it back quite a bit to keep the water levels right. I think you've found the problem.

 

[jddevinn]

So the mash flows through the pump, through the heat exchanger (with the cooling water not on) and then back into the mash ton? How big is the 3/8" copper coil in the heat exchanger? Assuming 30' it holds about 1/2 gallon. You are essentially 'removing' the volume that remains in the cooler from the mash. The volume under the 3" tall bottom also will not be mixed with grain at 14.5" diameter thats 4.25gal. Are you accounting for this ~5 gallons or is the mash too thick?

 

[StrngBrewer]

So the mash flows through the pump, through the heat exchanger (with the cooling water not on) and then back into the mash ton? How big is the 3/8" copper coil in the heat exchanger? Assuming 30' it holds about 1/2 gallon. You are essentially 'removing' the volume that remains in the cooler from the mash. The volume under the 3" tall bottom also will not be mixed with grain at 14.5" diameter thats 4.25gal. Are you accounting for this ~5 gallons or is the mash too thick?

I'm not sure I'm following you. I account for the "pump loss" by recirculating while I fill the kettle. The volume below the bag is what the element sits in and is constantly being recirculated out by the pump and back in down through the bag. My mash was definitely thicker, but that's because I miscalculated grain absorption.

 

[TexasWine]

OH! That reminds me, I did see some weirdness with the liquid level when I first doughed-in on Brew 3. Mine actually went down, but only for a while. It looked like I temporarily lost about 3 gallons for about 10 minutes but I couldn't figure out where it could have gone, what with the conservation of mass law. I'd just assumed it was absorbed into the grain, did it's magic and then came back out.

I'm assuming when you say the volume went down, you mean it went down in the sight glass. Is this correct? If so, then you were pumping from below the bag faster than the bag was allowing the wort to flow through it. What most likely happened is you dried out your "sump", partially exposing the element and causing scorching.

You have to be careful with a few things to avoid this. One thing I do is turn off the element until I get a good stable circulation flow going, meaning no changes in volume in my sight glass. Once stable flow is established I will then turn on the element.

There are several other best practices I've discovered when using a recirculating eBIAB. Just let me know if you're interested in hearing me ramble on about them.

 

[StrngBrewer]

Yes, "down" in the sight glass...

I'll run as TexasWine suggested next time and, hopefully, never run into this again.
Or I'll let you all know if it does.
Thanks for all the help.

 

[jeffmeh]

I think you have your answer.

Seeing the volume go down in the sight glass does indicate that your bag "stuck" and your pump emptied the liquid below the bag. Good luck.

 

[Bobby_M]

Recirculated BIAB has a sweet spot in the grind/crush and it has to be a little coarser than what most people advocate for BIAB. Another way to do it is make sure you dial the pump flow back a LOT. I mean, run it at less than 1 liter per minute. I watch my sight glass and when it's pulled down to about half the actual volume, I leave the pump valve there.