RIMS mash efficiency issues

[Pintabone]

I just recently switched to an electric system. I have a 5500W/240V element in my kettle and a 1650W/120V element in a RIMS tube. I recirculate through the RIMS tube the entire 60 min mash duration and have the return through a silicone hose running into the mash tun right around the top of the wort level. I fly sparge generally over 30 - 40 minutes.

I've only brewed on it twice but my efficiency has suffered significantly since making the switch. I brewed probably 20-25 batches on my old propane system with a single infusion mash. I think it's a combination of a reduced boil off rate since using the electric vs propane and my mash efficiency suffering. I'm not sure if it is something with how I'm recirculating and returning the wort in the mash.

Any thoughts are appreciated. I just brewed a Dubbel and missed the OG by about 12 points. It looks like it might be a session Dubbel.

 

[ProblemChild]

Mine went up. Good crush, fresh grain, and mash ph are keys obviously.

My mash thickness is often run at 1.125 to get a good sparge. constantly running the RIMS makes a tight grain bed. Not a problem, but is seems to affect the sparge. I generally run a thicker mash, drain the mash tun so no liquid is showing on top of the grain, fill back up to 2"
above the grain bed then start the sparge. Mash efficiency is steady at about 82%

 

[Pintabone]

I've generally run the mash at around 1.5:1. How do you return the wort when you recirculate?

 

[Genuine]

Definitely check your crush and you should be able to really dial in your boil off rate depending on what sort of power you're using. Once I get to boil on mine, I reduce power output to about 55-60% and I hit 1 gallon of boil off each time.

 

[ProblemChild]

I've generally run the mash at around 1.5:1. How do you return the wort when you recirculate?

MK-II wort pump. sits about 18" below the mash tun. inside the mash tun is the SS Brewtech recirculation manifold. use the fitting on the side of the tun to fit a valve and barbs. no splashing or spraying. THe manifold gets slightly submerged under the surface of the wort so there is no splash or spray.

 

[Pintabone]

Definitely check your crush and you should be able to really dial in your boil off rate depending on what sort of power you're using. Once I get to boil on mine, I reduce power output to about 55-60% and I hit 1 gallon of boil off each time.

Yeah I'm thinking my boil off is likely around a gallon now since moving to electric. I drop down to about 55 - 60% as well. I know that is a component but definitely not responsible for the 12 point miss. I think that may account for 5-6 points. The other must be from the mash.

 

[Smellyglove]

How do you use your rims? I've read that some people run it at full power and adjust temperature in the mash with the amount of flow, this denatures the enzymes. The rims should be at max just a little warmer than your target temperature in the mash.

 

[Pintabone]

How do you use your rims? I've read that some people run it at full power and adjust temperature in the mash with the amount of flow, this denatures the enzymes. The rims should be at max just a little warmer than your target temperature in the mash.

I run it probably medium flow through a Riptide pump. The temp probe is reading at the output of the RIMS tube and is set at the target mash temp.

 

[mongoose33]

I recently converted to all electric; same situation as you, 5500 boil element, 1650 RIMS element.

I struggled with lower efficiency at first too, what I did was tighten up the gap of the mill a bit, and I do a stir at the outset of recirculation (I underlet the grain to start), and then again after maybe 30 minutes.

To accommodate losses in the system (mash tun losses, hose losses, trub losses), I bumped up the recipe about 10 percent. When I did BIAB, I typically would use 7.25 gallons of water; with the new system, 8.0 or maybe a bit more.

The boiloff is less, but that's me turning down to a simmer and running the steam through a steam catcher.

 

[Smellyglove]

And you're getting the same post boil and preboil volumes as before?

At which point in the process do you first measure that you're off?

 

[Pintabone]

And you're getting the same post boil and preboil volumes as before?

At which point in the process do you first measure that you're off?

Pre boil volume is the same as I manage that through sparging until reaching preboil volume. Post boil is definitely higher as I think I'm not boiling off as much as I throttle down the element power. I know that is impacting the efficiency as the equipment profile still had my old boil off rate. I will adjust that going forward. However I'm definitely losing efficiency in the mash.

I measure I'm off in the pre boil gravity first. Although the Dubbel indicated I was a point below target. However I think that was a bad reading because I can't imagine how boil off would raise 12 points. My boil off is likely only maybe half a gallon lower from about 1.5 gallons where I was with propane. I filled the kettle to target volume and let it get up to a boil hoping to get a good mix of the wort. Then took a sample from the drain valve. I'm guessing that the wort wasn't fully mixed up and may have sampled more dense wort leading to an artificially inflated gravity.

 

[FunkedOut]

1st thought is to confirm that you are, in fact, losing efficiency.
Just because your OG is 0.012 low, doesn't mean you've lost efficiency. If you have more wort volume, due to less boil off, your efficiency might not have changed at all.
Compare gravity and volumes before and after the adoption of the new equipment to find out what has changed.

2nd thought is about the mash tun design.
Channeling can be a cause for efficiency loss.
A false bottom and pick up location that promotes evenly distributing the collection of the wort beneath the grain bed will reduce the likelihood of channeling.
By the same token, so will distributing the sparge water (or recirc return) evenly across the top of the grain bed.

Next thought is about flow rate.
Once, you've reached even distribution of supply and return, flow rate is paramount.
If you are pumping too fast, you will compact the grain bed enough to impede flow and create channeling.
Flow rate is largely dependent on the parameters mentioned above as well as the grist (amount, composition and crush).
Because of all those variables, it's hard to give a recommendation or even a rule of thumb for flow rate.

Just as a single data point, I recirculate at a rate of 2 quarts per minute.
18" diameter mash tun.
I have a false bottom over a 5° sloped mash tun floor draining into a centered bottom hole.
Return is distributed over the bed with a 12.6" diameter manifold.
My grist is usually 10lbs - 15lbs, 85% - 100% barley, crushed with a 0.035" gap (fairly fine).
Never had a stuck sparge until recently, with a 28lbs grist.

Final thought is about temperature.
With a steady flow rate selected, you should tune your PID controller for the RIMS tube.
Flow rate will greatly affect your PID parameters, so I find it best to keep it constant.
Monitor the RIMS tube with a probe a couple inches away from the heating element.
That will be the hottest temperature your wort will see, and should be kept at the target temp (or just a couple of degrees more) to avoid denaturing enzymes.

 

[Pintabone]

1st thought is to confirm that you are, in fact, losing efficiency.

2nd thought is about the mash tun design.

Next thought is about flow rate.

Final thought is about temperature.

Didn't want to quote your entire message but thank you for the long thought out reply. I know the boil off component isn't necessarily tied to the efficiency of extracting the sugars into the kettle. I will adjust my equipment profile to get closer to the boil off rate so that should account for some of the loss.

I'm using a 10gal SS Infussion mash tun with their false bottom and sloped bottom drain in the center. However I'm recirculating through the top return port to a 1/2" silicone tube that I lay in the tun to return near the top of the wort. When sparging I swap the tubing for a piece of PEX water line with holes drilled. I don't use this while recirculating the mash because the bits of grain would clog it.

RIMS probe is set up exactly as you comment.

 

[doug293cz]

In order to actually diagnose efficiency problems, you need to know it it is your conversion efficiency that is low, or your lauter efficiency that is low, or maybe both.

Mash Efficiency = Conversion Efficiency * Lauter Efficiency​

You can determine conversion efficiency using the method here. Most brewing software can calculate your mash efficiency based on your grain bill, pre-boil volume, and pre-boil SG (or alternatively post-boil volume and post-boil SG [i.e. OG].) You then calculate your lauter efficiency with the following formula:

Lauter Efficiency = Mash Efficiency / Conversion Efficiency​

Ideally conversion efficiency would be between 95% and 100%. If you are below 90% then there is something wrong with your mashing process.

Conversion efficiency depends on the ratio of grain bill weight to pre-boil volume (this is different than mash thickness) and the sparging process you use. The chart below summarizes this.

The solid lines are appropriate for a traditional MLT, and the broken lines for a well squeezed BIAB bag. With a good fly sparge, you should be able to get better lauter efficiency than the top (green) solid line. If not then your sparge process is deficient.

Once you know where the problem lies, you will have a better idea where you need to look to fix it.

Brew on

 

[FunkedOut]

@Pintabone
I am using the same mash tun!
I am using the SsBrewtech recirculation manifold up top.
When I used just a hose, it basically bore a hole in the grain bed. When your grain bed runs dry, is it level?
What’s your flow rate?
What’s your crush?

Looks like you’ve covered most your bases already.
Agree with @doug293cz , you need to figure out if you have a lauter issue or conversion issue.

I just brewed a 10lbs grist for 60min that was 10% wheat and managed 90% effeciency with a much quicker sparge; less than 30 min.

Last place you could look is pH, but I’d rule out process first.
Specially since that’s what’s changed.

 

[Vale71]

I second the advice of using SSB's manifold to ensure a more even distribution of recirc water.
I'd also recommend milling with malt conditioning in order to preserver the hulls better. This will give you a grain bed with higher, more uniform porosity which will work towards preventing compaction and channeling, besides possibly allowing for higher flow rates overall.

 

[Pintabone]

Thanks guys, I have some leftover pex that I can make a better recirculation manifold out of similar to the SS version. Hopefully that will help distribute a bit better. Does that manifold just kind of float above the grain bed near the top of the wort volume?

The grain bed definitely isn't even after I'm done filling the kettle so channeling may be more of an issue than in the past when I wasn't recirculating. The flow rate is mid level on the Riptide, haven't measured it exactly. Crush is probably just above .035 probably. I'm not looking for an outrageous efficiency in the end. Just to get back to a more consistent level.

 

[FunkedOut]

...The Infusion Mash Tuns were originally designed to operate with a lautering/run-off velocity up to 1.5inches/minute, which is equal to about 1.4 gallon per minute. You can potentially increase your efficiency by slowing down the run-off rate, yet testing has indicated that a rate of less than 0.5 inches/minute is considered to be slower than necessary. Conversely, run-off rates greater than 1.5 inches/minute will be less efficient and elevate the risk of a stuck sparge....

https://ssbrewtech.zendesk.com/hc/en-us/article_attachments/202260693/Infussion_MT_WP_V1.0.pdf

That Riptide is capable of close to 7 gallons per minute at a couple feet of head. Midway would be 3-4.
That’s 6-8 times my flow rate. Coupled with the hose that’s washing your grain bed around, I think you found room for improvement.
I measured the flow rate with a large measuring cup and the second hand on my watch.

I use gravity to drain into my kettle. And when I do that, ball valve completely open, it drains at about 0.5 gallons per minute. I don’t want to recirculate faster than I lauter, although many do. Trade off is being patient with any steps on the mash schedule. It takes my rig about 1 min per degree temp raise.

That manifold doesn’t float at all. It sits on the bed. If the bed is still floating, like right after underletting and stirring, it will sink about a 1/2”. I will pull it up by the hose, rotate it 45* and let it back down at about the 20min mark, when I’m pulling a pH sample from the return port.

 

[brewbama]

My setup is similar to yours. I use a cooler mashtun with a false bottom and a Brew Bag as a filter. I use a RIMS tube and recirculate thru the entire mash. I found three variables thru research, trial, and error that has resulted in consistent mash efficiency: 1) I use a fairly thin mash 1.75 qts/lb. 2) I use a fairly coarse crush to allow permeability of the grain bed. 3) I use a consistent setting on my pump output linear flow valve (5/16”). These three variables allow flow across the heating element without getting stuck causing pump cavitation while simultaneously giving me good mash efficiency (routinely 92 plus or minus 2).

This is what I learned on my system: Crushing too fine promotes channeling around the grain bed vs flowing thru it by pumping the fine flour unto the top of the grain bed. This layer has to be permeated to allow flow thru it otherwise the wort flows around the impenetrable layer. Pros use knives to cut what the Germans call ‘Tieg’. The starches will convert even when not ground to flour. A fine crush was OK when I did set it and forget it single infusion but not with my continuous recirculation. I base this on a study by Rock Bottom breweries and Darcy’s Law.

The thin mash is based on Kai Troester’s research. The pump setting is based on trial and error over several brew days.

I should also mention I use a Hockhurz style mash. I use 145*F for 30 min, 150*F for 30 min, 160*F for 45 min, and mash out at 170*. I pump crystal clear sweet wort into the boil kettle.

I get very consistent predictable results with this setup on my system. I believe each system is unique and requires an individual setup.