Anybody else scorch wort with a RIMS element?

[wardenwheat]

In 5 batches with my 120 volt - 1500 watt element, I've scorched two batches of Hefe. I don't know why that is. Seems to work with all the other beers, but I do an acid rest at 110 then run it up to sacc rest temps. I'm going to quit using it to step my temps and just hold from now on. Any suggestions???

 

[samc]

Lower flow due to the wheat? Use rice hulls.

 

[trigger]

There's been some discussion recently on this topic. I've tried protein rests, adding water salts to "salt out" the protein that builds up on the element, and not heating for the first 10-15 mins of recirculation. All of them failed. My solution has been to increase wort velocity across the element so that it is pulling heat away before the element can create those little pockets of steam that allow the buildup to burn. Rice hulls will help with keeping the mash from sticking when recirculating fast. Other than that I haven't been able to prevent the buildup that's causing the problem in the first place.

 

[wardenwheat]

I've been using a thin mash - 5 gallons to 10 lbs of grain. I do an acid rest for 15 mins. Start the pump, (which is running about 1.5 to 2 gallons a minute) and let it run for another 15 mins and then start the heat. Even then it seems to want to scorch. I'm just going to use my element for keeping the sacc rest temp and for warming my strike water. Very dissapointed......

 

[ScubaSteve]

When you say scorch, what do you mean? Does the wort have a burnt taste? You WILL get some buildup on the element, and that's normal. Just wipe it off with a sponge after each brew.

Maybe you should get a low density element....it'll be folded over and have more surface area....so the heat at the element will be less intense but still transfer just as much energy.

 

[trigger]

When you say scorch, what do you mean? Does the wort have a burnt taste? You WILL get some buildup on the element, and that's normal. Just wipe it off with a sponge after each brew.

Maybe you should get a low density element....it'll be folded over and have more surface area....so the heat at the element will be less intense but still transfer just as much energy.

Yea, I get the buildup with all barley beers, but when I use more than 30%ish wheat or rye the buildup is so thick that it insulates the element. If the flow isn't fast enough the buildup literally burns on the element, like the inside of a dirty oven. I've probably had this happen in about 8 batches of beer, a couple were so bad I ended up dumping them. The bad batches literally tasted like burnt bacon. The not so bad batches had a smokey flavor. The really bad part is that if I didn't get every last little bit of burnt stuff off it would catalyze the same thing in all barley batches. I tainted a batch of american pils by not cleaning the element completely.

 

[wardenwheat]

I have a low density element. I have to soak my element in oxyclean every time to remove any residue between brews.

 

[shushikiary]

I have had this exact same problem. It's definitely scorching, a nice burnt grain smell and then POP goes the element if you let it go long enough, and by pop I mean it blows my GFCI sense its resistance to ground got below 3 mega ohm (I measured it) which at 240v (what I run at) is enough to cause enough leakage current to pop to the GFCI.

I tracked the problem down to 2 issues. One is too low a flow rate, the other is flow in the RIMS tube.

Originally I had a flow switch on the output of the RIMS tube and a flow control valve. First time I scorched it would happen any time I tried to restrict the flow so I wouldnt get a stuck mash. After some thought on it I realized that if I was restricting the output of the RIMS tube you could cause some very interesting circular flow issues inside the RIMS tube which can cause scorching even at high flow rates.

So I moved the valve to the input side of the RIMS tube and made sure there was enough tubing to balance out the restricted flow into a nice constant rate after the valve before it entered the RIMS tube. This solved the first time it poped.

The second time was the same issue, but due to the restriction of my flow switch. I removed the flow switch and didnt change the flow rate, problem solved.

So the lesson here is two fold. NEVER restrict the output side of the RIMS tube, only the input side, making sure that the flow is consistent and in one direction through the entire tube (aka let there be some tubing after your flow restriction valve to even out the flow before it enters the RIMS tube). Second, try to keep your flow rate around 1 GPM or higher if you can, go as fast as you can without compacting your grain bed.

A good way to measure the flow is to put a vacuum gauge on the input of your pump, and then always make sure to have very little to no vacuum there when restricting your flow rate, this will keep you from compacting your grain.

Next, get the largest area false bottom that you can, and use rice hulls. They help, A LOT. Use 2% of grain bill weight of rice hulls, aka 10lbs grain bill, add 0.2 lbs of rice hulls. This will help you keep your recirc rate up without getting vacuum.

The combiniation of all of the above is what solved the problem for me... it also upped my efficiency by 17% (due to no longer compacting the grain bed during mash).

As a final solution to the problem I'm going to switch to a true HEX, were wort gets its heat from RIMS heated water through a wood furnace hot water HEX, that way you CANT scorch the wort even at stupid low flow rates as the flow rate through the RIMS will be held at max the pump can do and so the output temp of the RIMS will be held at what you want it to, and so any wort that goes into the HEX cannot exceed that temp. You loose a little bit of energy efficiency due to lower heat transfer, but I think it's worth it.

 

[Walker]

POP goes the element if you let it go long enough, and by pop I it blows my GFCI sense its resistance to ground got below 3 mega ohm (I measured it) which at 240v (what I run at) is enough to cause enough leakage current to pop to the GFCI.

You've lost me here shushikiary.

Resistance of "what" relative to ground?

And what leakage current are you talking about?

 

[shushikiary]

So both legs of the 240v element, when they are brand new, have a VERY large resistance to the metal part of the element that has the threads on it. Usually in a house because the hot water heater is tied into the copper house pipe and the copper house pipe is used for earth ground, the threaded part of the element is tried to earth ground.

My rig is setup the same way, the entire thing is grounded, and so thus in my RIMS tube when the element is threaded in the threaded part is tied to ground as well. That's the ground I was referring to, earth ground.

So after scorching has happened I re-measured the resistance of both screws on the heating element and they both (duh it's a resistor) read under 2 megaohm of resistance to the metal thread part of the element, aka earth ground.

Thus due to this reduced resistance at 240v RMS we have 1 - 2 mA RMS of current that is leaking from the hot to earth ground. Where before it was well over 200 megaohm.

Sense the GFCI operates based on measuring the current difference between current leaving and returning on both hot wires (red and black) the return current will now be off by 1 - 2 mA because that much current is going to ground now through the 1 - 2 megaohm resistance. And that's enough to pop most GFCI's.

 

[Walker]

Hmmm.... I'll check when I go home, but I was under the impression that there is NO path the threaded base from the hot connections on an element. I 'll be getting my multimeter out tonight for sure.

That aside, the GFCIs we use trip at 5mA. To get 5mA of current from 240V, you would need a relatively low resistance path from to ground. Less than 50kOhm...

 

[shushikiary]

Class A GFCI's are set to break at a current no greater than 3 mA. Class A is what is supposed to be used for house hold GFCI in bathrooms, etc.

The GFCI I have is a class A but exceeds the requirement, I've measured its breakage current at 0.8 mA.

 

[Walker]

OK. I am seeing just tons of references to 5mA via google for a class A GFCIs, but that's a secondary thing at this point and not what I was most curious about. I'm more interested in the fact that there is an electrically conductive path between the hot connections and the threaded base of the element. That's news to me and I was totally unaware of it.

 

[shushikiary]

Yea, I was very weirded out when I would get scorch smell and the GFCI poping, haha. So I measured and sure enough...

I'm just regurgitating what I've been told about class A GFCI's here on the forums, so who knows what is right.

I did measure what it takes to pop mine just out of curiosity though after this whole thing was going down and sure enough, it only took 0.8 amps RMS, even though it's rated for either 3 or 5 mA. I guess in this case I'm glad its that way because I'd rather have it be that far off in that direction than the other, its much safer.

 

[Walker]

yeah, I think the GFCI requirements are stated that it must trip in X amount of time with Y mA or more, so as long as that is true, then the device qualifies. So... tripping at 0.8mA makes is in the class A range... WELL in it.

But, I think you're still off on something. If you have found the trip current to be 0.8mA on your 240V service, then it means you have a 300kOhm path or less (not 3MOhm) on your element. That seems wrong to me.

 

[shushikiary]

Yea, but also remember that the resistance might be changing with voltage. If there is a dielectric in the element that is the insulator to ground and it melted away due to over heating during the scorching event it's possible that there is an air gap of some kind. A very small air gap at a volt meters voltage could (like a few microns or something) look like 2 megaohm, but at 240 volt you could arc and make it much less, or if you say ionized the insulator so now you have a highly ionic gas in the gap that conducts much better once you arc but then doesnt at low voltage (like how air works).

What I know for sure is that if I take the whole RIMS tube apart after a scorch but leave the element hooked up to the hots and ground the GFCI pops the second I turn it back on, if I remove only one hot line the GFCI still pops, if I remove both it does not. If I put a new element in it does not. I also know that a new element measured over 200 megaohm (beyond the multimeters range to measure), but after the scorch event it would measure (on 5 different elements I've scorched in the process of figuring this out) between 1.2 and 2 megaohm on the elements, the measurement was consistent for each element on re-measure, but each one varied between that range.

So something in the resistance of the element to earth ground changed during the scorching event. I wish I had an O-scope at home so I could hook it up and watch what happens as the GFCI pops so I knew more, haha, but knowing for sure that the element is the issue and the thing that caused it is the scorching is enough for me. The goal is just to replace the element and stop the scorching.

It's also possible, depending on the design, that the GFCI may work on peak current and not RMS current... which would make a small difference as well.

 

[Walker]

I wonder if you actually dry fired your element? That would leave a horrible burnt smell as well as cause the inner workings of the element to heat up excessively (no liquid to carry the immense heat away.)

 

[shushikiary]

it doesnt appear that way. Looking at the element the entire thing is covered in black burnt material that I can scrub off, and the element its self smells very strongly of burnt grain, as if you put dry grain in a pot and put it on your stove too long.

I've dry fired elements in the past and everyone I've done that to they crack and open a small hole in which water gets into and then causes the GFCI to pop. If I let the element air out and turn the GFCI on then it doesnt pop on those guys, so it seems like the water getting in the hole is the issue on the dry fired ones in my experience, and they didnt have the black material that I could scrub off on them, and the smell was more of a brazed metal than a burnt grain.

On all the dry fired elements I've had if I over heat them the GFCI pops, but then if I turn it back on right away it doesnt pop. Put it in water and it pops right away. The scorched ones pop right away no matter how long I let them dry out, in water or out of water, etc, they always pop the GFCI.

I suppose I should state that I only turn off 1 leg of hot on my heating elements so when the GFCI is turned on there is always 1 hot side, the other side is shut off with a SSR.

The elements I buy for the RIMS are camco ones and on the boxing it says they can survive dry firing, so to me the evidence points to the scorching and not dry firing.

 

[Walker]

Beats me. Just thinking outloud.

I dry fired a 5500W camco element after a brew session. One of the black "incoloy" ones. ULWD, capable of withstanding a dry firing. It still had wort residue on it from the session (had not cleaned it yet). The garage instantly smelled like burnt organic matter and the element ended up with black crust on it that I was able to scrub off with a nylon scrubber.

The element did indeed survive and continued to work, but the plastic part on the back where the screw terminals are partially melted and I ended up replacing the element anyway.

 

[shushikiary]

Hmm...


Well, if it was dry firing you'd think that only one part of the element would end up burnt I suppose... Of the latest elements that have poped the GFCI from "scorching" there was actually a decent flow rate (over 1gpm) when it poped.

Though, I suppose that after removing the output restrictions on the RIMS tube it might have flushed air bubbles out better. I guess the only real way to tell would be to mount the RIMS tube vertically instead of horizontally like I have it now.

I'll also add that the last time it blew there was the high flow rate like I said, however it was a grain bill with a fair amount of flaked wheat, and when we took the RIMS tube apart there was a LARGE build up of what I'll call "slop" inside the tube that got stuck in there built up around the heating element, and that was very burnt. The slop near the end of the tube was still slop, but the slop that was on the heating element was burned black and the surrounding slop was decreasingly black leading away from the element.

It makes me wonder if in wheat grain bills the extra crap that gets past the false bottom makes that slop build up in the RIMS tube if you dont have a good clean consistent flow (the last one blew with the flow switch on the output of the RIMS tube, and then on the same batch, 2 hours later after I cleaned the tube and put a new element in to continue the brew day and removed the flow switch, it never scorched again and we finished the brew) the turbidity of the flow in the tube causes it to drop out the "wheat" particles in the RIMS tube and as they build up you reach a point where you scorch and/or technically dry fire as if the element was in stagnant "slop" as the rest of the flow goes over the "sand barge" of slop that lays to rest at the bottom of the RIMS tube.

If the above is the cause of the problem turning the tube vertical to get rid of air bubbles would exacerbate the problem as the slop would built up starting at the base of the element rather than where the temperature sensor is.

 

[trigger]

Here's my take after playing around with my own RIMS:

As far as the elements "popping" I think you're right on. I would wager that the element got hot enough to break down the insulative packing in the element, and provided a lower resistance path to ground. This path would be from the internal resistor to the metal jacketing around the element.

I have noticed that the sludge that forms around my elements only scorches when it gets thick enough. I believe that this is a function of the sludge acting as an insulator around the element. I propose that the sludge traps steam pockets formed on the surface of the element, separating them from the liquid flow. The element is then able to heat these pockets above 212 F, in turn burning the sludge and leading to the element overheating. There must be a separation formed between the liquid column and the element surface, otherwise the sludge wouldn't burn.

Finally, I agree that there is something special about wheat and rye that cause a greater amount of sludge to be formed. If you look at a malt analysis they don't contain that much more protein than barley. The difference must be in the nature of the proteins. For some reason they are less soluble than barley proteins, and I believe that they must have a higher net electric charge, causing them to be attracted to the element surface.

 

[pickles]

This is discussion is so timely. I was brewing a wheat beer this weekend while doing some yard work. I came back to check on the mash about 10 minutes in and the GFCI had popped, I reset it and the brewtroller started up and things went on. I realized a bit later that mash temps were dropping so I assumed that something happened to the RIMs element and it's fuse blew. I was really busy so I just let things go and the mash temp only dropped a bit and I haven't investigated the problem yet. When I randomly came across this thread it really got me thinking; when i first saw that things went wrong I noticed a little bit (1/2" circle) of black foam on top of the mash bed along with the typical tan foam. So I wonder what happened? My element is a low density version and it doesn't appear to be dry fired.

 

[bbognerks]

Both BuzzedBomber and myself have scorched wort when using our RIMS tubes. We had the LWD 1500 watt 120v from PlumbingSupply. We noticed a scorch smell on his batch several times through out the mash. I only noticed it once on mine. Either way, once it's scorched, it's ruined.

I should note that in both cases, the scorching happened because we were trying to ramp temps. He was trying to ramp temps because he thought he could. I was ramping temp because I missed my sacch rest temp. I also was making a recipe with a large wheat bill and dealing with a very slow recirculation.

We have both since switched to 240v 4500w LWD elements running on 120v. I ran my first test batch with it with no ill effects. He just brewed his first batch 3 days ago. We'll see in a couple weeks.

I really would have thought scorching was difficult to do. I saw very few reports of people scorching prior to having experienced it myself. With as many people that swear by using RIMS, I would have thought there would be a lot more people scorching wort as they were learning to use the RIMS tube...

If I had to do it over again, I would probably opt for a HERMS. I still may if I continue to have scorched wort.

 

[pickles]

I haven't had any problems before this wheat beer. I can typically run full throttle through the RIMs but the wheat had everything slowed down, almost stuck. I had to thin the mash to about 2 qts/lb to get it to flow, whereas I typically use 1.25 qts/lb. I definately think it is the wheat that caused the problem, not an inherent issue with the RIMs design.

 

[Sawdustguy]

I am going to get flamed but I have always maintained that RIMS is for maintaining mash temperature only. Thats why I always try to brew with fully modified malts. With a fully modified malt a single infusion mash is sufficient so I never to use the RIMS to step. I think we are seeing more and more that using a RIMS to step is going to lead to problems. I think that one has to consider that to step you need to introduce a lot of heat into the mash which demands a slow flow to transfer the heat into the fluid flowing through the RIMS Tube. Thats where the trouble begins. I think if someone wants to step with a RIMS some direct heating of the Mash Tun or decoction has to take place for the step and the RIMS with maintain the rest until it is time to step again.

 

[pickles]

I agree with you SawdustGuy, but in my case I wasnt step mashing and never have. Even when I mashout, it's the sparge water that brings things up to temp for the most part. The Only thing I did differently this time around was add wheat to the recipe. I've since looked things over and indeed I fried my element but it doesn't look split open like others I've dry fired.

 

[PaulHilgeman]

Are you sure that you didn't leave the element on after you were done with the mash etc ?

 

[pickles]

No that didn't happen. As stated above, the Brewtroller was in charge and it happened ten minutes in to the mash. The gfci tripped and I had to reset it.

 

[mattd2]

I wonder if you actually dry fired your element? That would leave a horrible burnt smell as well as cause the inner workings of the element to heat up excessively (no liquid to carry the immense heat away.)

it doesnt appear that way. Looking at the element the entire thing is covered in black burnt material that I can scrub off, and the element its self smells very strongly of burnt grain, as if you put dry grain in a pot and put it on your stove too long...

...The elements I buy for the RIMS are camco ones and on the boxing it says they can survive dry firing, so to me the evidence points to the scorching and not dry firing.

I'm still wondering if you did actually "dry" fire the element. If you are getting a lot of buildup on the element that could cause a similar situation (or even worst) to dry firing as the heat won't be taken away from the element quick enogh and cause it to pop. For this reason I would guess even a ULWD element could dry fire under these conditions. I also thought the dry firerable (is that even a word) element s could only survive for a short time, not being left on. Just my $0.02 on the whole situation and I apologies if this had already been covered as I'm at work and did not have time to read the last few posts

 

[Strongbad52]

This seems like an elegant solution that I saw on the "Rims for Dummies" thread (page 81 of thread) -There is no heating element in the pipe. It's basically an external version of a HERMS system.

He wraps the outside of the pipe with extreme heat tape (The tape is a heating wire inside of a shielding, which is powered by 110VAC). The heat is applied to the outside of the pipe, like the coil in a HERMS.The pipe with the heat tape is the enclosed in insulation.

here is his parts list from McMaster-Carr --

1 1 each 4550T141 Extreme-Temperature Heat Tape 13 Watts/Square Inch, 8 ft Length, 624 Watts, 120 V today $69.07 each 69.07
2 2 each 4464K51 Type 304 Stainless STL Threaded Pipe Fitting 1/2" Pipe Size, Tee, 150 PSI today $7.18 each 14.36
3 1 each 4813K124 Standard-Wall Type 304/304L SS Threaded Pipe 1/2" Pipe, 0.84" OD, 18" L, 13/16" Thread Length today $18.65 each 18.65
4 2 each 4464K234 Type 304 Stainless STL Threaded Pipe Fitting 1/2" Pipe Size, Square Head Plug, 150 PSI today $3.21 each 6.42
5 1 roll 9379K92 Ultra-High Temp Foil-Faced Insulation Strip 1/2" Thick, 2" X 12' today $11.39 roll 11.39

Merchandise total
$119.89 Of one section. I used two for a total of 1200 watts..

When I finally get around to fabricating a bottom drain keg for my mash tun, I think this is the way i will go rather than an internal element.