RIMS inline water heating question

I have a RIMS system I built with knowledge gained from amazing people in the forum (pics below)! I absolutely love my system and I've probably brewed 15 or so batches using the system. My efficiency went from the high 60's to high 80's low 90's which is what I was after.

The issue I seem to have is in the sparging. When I'm heating sparge water inline with the RIMS tube the temp is all over the place. If I set the PID 172*, the temp will climb past 172* and then I can see the element is turned off and as soon as the temp drops below 172 the element will come back on but the cool water coming from the tap (~72*) will have already passed the element while it was off so the temp drops to ~130* before climbing back up passed 172* and the process is repeated. This gives me an average sparge water temp around 160*. Raising set temp will fluctuate between boiling and 140*.

If I put the PID in manual mode the sparge water will eventually reach boiling temps which a quick increase of water flow will mitigate momentarily before climbing back to boiling.

When I'm sparging the 5500w element is running at 240V. If I run the element at 120V (quarter power) it is unable to heat the water to 172* at the sparge flow rate.

I'm able to mange this by watching closing but it's definitely not set it and forget it - which is what I'm trying to achieve.

Are any of you with RIMS systems able to set the sparge temp you want and leave it?

Your thoughts and suggestions are greatly appreciated!

A question first - are you heating your sparge water directly from the tap via the RIMS tube and adding that to your MLT? It could be a change in water pressure that's causing the problem.

stlbeer said:

A question first - are you heating your sparge water directly from the tap via the RIMS tube and adding that to your MLT? It could be a change in water pressure that's causing the problem.

Click to expand...

Yes, the water goes from the tap to an inline filter to the RIMS tube to the MLT.

I don't mean to sound like I'm knocking RIMS setups but I think this illustrates an advantage of a HERMS setup. Since a HERMS has more thermal mass it doesn't fluctuate as much. But they probably also respond slower than a RIMS when you want to increase temp (e.g. step mash). How high is your flow? If it is pretty high, perhaps slowing it down a little so that the given portion of liquid is in contact with the sensor and element a little longer.

That's a pretty cool idea. My RIMS tube only at a 2000w 240v element in it. I would think your flow rate would have to be fairly slow and with the variability of water pressure that could make for the difference you see. Also, it could be inadequate mixing of the heated portion of water at the temp probe. Is your temp probe long enough to get into the main column of water? I see it's in the side of the tee, but that could be part of the problem as well. Have you considered insulating your RIMS tube? There is heat loss there as well. Possibly a water regulator on the input side (ball or gate valve) separate from the valve at the tap?

I too am having the same problem with my new Rims setup. When run in auto, I would get huge swings, so I switched it to manual. Now my problem is trying to get a 1/2 ball valve to open the exact amount for the flow I need. After playing with it for a while, I was able to get it steady at about 165-170, but it is extremely touchy. I will either need to put in a smaller valve, or something with better ability to fine tune it. Really though, I just need to figure out how to program the PID better.

If I'm not mistaken, user Sizz had the best success by injecting incoming tap water on the input side of a recirculation loop. For example, say you have a gallon of water in your MLT and you start pumping it through the RIMS as if it was in mash mode (controller set at desired strike temp). Meanwhile, the incoming tap water is injected post pump, but pre RIMS via a tee and valve. The incoming flow rate remains generally slow to allow the filter to remove chlorine, etc.

He was using a BCS through so even in auto temp mode, he was able to fine tune the duty cycle to a very short period to avoid swings.

phreaky said:

I too am having the same problem with my new Rims setup. When run in auto, I would get huge swings, so I switched it to manual. Now my problem is trying to get a 1/2 ball valve to open the exact amount for the flow I need. After playing with it for a while, I was able to get it steady at about 165-170, but it is extremely touchy. I will either need to put in a smaller valve, or something with better ability to fine tune it. Really though, I just need to figure out how to program the PID better.

Click to expand...

I did the same thing and put a stopper on the tap line ball valve so I could hit the same flow rate every time. The issue is I have to get a pretty good flow rate in order to stay at 175-180 so the flow to my kettle is less than the flow to MLT. If I were to make them the same flow rate the sparge would be over in less than 30 minutes...I'm not sure if this is a problem or not but I assume it will decrease efficiency.

What size is your element? I wonder if I drop to a 4500w will correct the issue.

stlbeer said:

That's a pretty cool idea. My RIMS tube only at a 2000w 240v element in it. I would think your flow rate would have to be fairly slow and with the variability of water pressure that could make for the difference you see. Also, it could be inadequate mixing of the heated portion of water at the temp probe. Is your temp probe long enough to get into the main column of water? I see it's in the side of the tee, but that could be part of the problem as well. Have you considered insulating your RIMS tube? There is heat loss there as well. Possibly a water regulator on the input side (ball or gate valve) separate from the valve at the tap?

Click to expand...

The probe is approx 3in. I think I'm getting good readings and adequate heating at my flow rate given the sparge water will reach boiling if I put the PID into manual mode. The PID controller is on its most sensitive setting and I don't see anything in the manual that leads me to believe I can fine tune it further. I'm really starting to lean towards replacing the 5500w element with a 4500w to see if lower wattage element will heat the water to the desired temp without reaching boiling.

Bobby_M said:

If I'm not mistaken, user Sizz had the best success by injecting incoming tap water on the input side of a recirculation loop. For example, say you have a gallon of water in your MLT and you start pumping it through the RIMS as if it was in mash mode (controller set at desired strike temp). Meanwhile, the incoming tap water is injected post pump, but pre RIMS via a tee and valve. The incoming flow rate remains generally slow to allow the filter to remove chlorine, etc.

He was using a BCS through so even in auto temp mode, he was able to fine tune the duty cycle to a very short period to avoid swings.

Click to expand...

So the wort from the mash tun is mixed with fresh water from the tap before hitting the RIMS tube? If I'm understanding this correctly I would have to add all my sparge water before emptying the MLT because I can't drain the MLT at the same time I'm mixing, correct?

brewsme said:

So the wort from the mash tun is mixed with fresh water from the tap before hitting the RIMS tube? If I'm understanding this correctly I would have to add all my sparge water before emptying the MLT because I can't drain the MLT at the same time I'm mixing, correct?

Click to expand...

Not really mixing the existing wort with the fresh water. He has fresh water come in the Rims tube, get warmed up, then exit, and part goes into the kettle, while part goes into a pump, which puts it right back into the rims tube with the fresh water. The idea is that the element has lots of water flowing over it, but only a little fresh cold water being added, and the same amount of hot water exiting the loop.

https://www.homebrewtalk.com/f51/rims-build-129646/

I bought a 4500w lwd element and replaced the 5500w ulwd element. I figured for $11 shipped it was the cheapest option to try. So far in my testing at .25 gpm the water heating inline would not reach boiling. It would reach the 190s after 30 minutes or so but I will only be sparging for approximately 20 minutes. I have a brew lined up this weekend so I'll report back after an actual brew day.

I have a 2000w 120v element. But, I heat my sparge water in my HLT to about 150 to 160. The tube just bumps it up to 168 and holds the temp pretty well.

sounds like we are having the same exact problem, at the same time. My RIMS looks exactly like yours, except in tri-clamp form. Probe placement and in/outlets.

we had a eureka moment this morning, and I am dying to test it out. WHAT IF I could reverse the outlet section of the tube so that the sensor is in the middle of the tube, very close to the heating element? so then, there is no delay from the element heat to the sensor, like you have in your tube. for me, this is not a problem because the probe will not protrude into the element leads at all.

to visualize this scenario, visit the brewershardware.com rims tube section. the main page has a disassembled view of how i currently have it configured. i plan on swapping the right side of the tube, so that the tri clamp is in the center, and have the outlet be at the new end of the tube.

https://www.brewershardware.com/images/RIMS15.jpg

kinggoo said:

sounds like we are having the same exact problem, at the same time. My RIMS looks exactly like yours, except in tri-clamp form. Probe placement and in/outlets.

we had a eureka moment this morning, and I am dying to test it out. WHAT IF I could reverse the outlet section of the tube so that the sensor is in the middle of the tube, very close to the heating element? so then, there is no delay from the element heat to the sensor, like you have in your tube. for me, this is not a problem because the probe will not protrude into the element leads at all.

to visualize this scenario, visit the brewershardware.com rims tube section. the main page has a disassembled view of how i currently have it configured. i plan on swapping the right side of the tube, so that the tri clamp is in the center, and have the outlet be at the new end of the tube.

https://www.brewershardware.com/images/RIMS15.jpg

Click to expand...

I think there would still be temperature swings but having the probe closer to the element will make them smaller. The problem is when the element is on at 5500w with .25 gpm the water heats up beyond your set point so the element is turned off. Cold water starts filling the tube until it reaches the probe turning the element back on but at this point you have x number of inches of cold water that was only heated from the heat exchange in the tube.

The problem here is not related to your input water pressure fluctuations. I would suggest installing a flowmeter, so that you can monitor the rate of flow. Using this, you could figure out a rise in temperature per rate of flow. Something along the lines of - degrees per minute per gallon per minute, or degrees per gallon. It would be an inverse relationship - where you might get a rise of 5 degrees per gallon, which would mean that 1 gpm gives you 5deg/min and 5 gpm gets 1 deg/min. Once you've figured out these relationships, you just dial in your flow rate, and let it go.

I also apparently should have installed a ball valve on the RIMS outlet, to regulate the flow. i will be trying a butterfly valve as i am just fresh out of on-hand tri clamp ball valves. i was able to get the temperature on sparge between 161-169 by relocating the probe midway through the tube, and basically on top of the element. i imagine that when i am able to actually regulate the flow on the outlet of the rims with a ball valve, the swings will go away entirely.

I had success this morning running a water test for mashing and sparging with the same PID values after:

1. Relocating temperature probe to the middle of the tube.
2. Changing my fresh water source to a lower flow spigot.
3. Placing a valve on the outlet of the RIMS tube.
4. Tinkering with the valve on the outlet of the RIMS tube and the water-in shutoff valves on my manifold.

For reference (although your system will be different), my PID values for P,I,D were:

I=265
P=14
d=25

Hope this helps.

So after changing the element from a 5500w to a 4500w I recalibrated the PID using the auto tune feature and this eliminated the temperature swings! :rockin:

When doing the auto tune I put the system (valves) in sparge mode, set my gpm to .25, and set the set point on the PID to 180*F. Once the temp reached 180*F I started the auto tune by switching At=2 and let it run until it stopped flashing on its own. During this time there where huge swings (130*F - 186*F). After the auto tune completed the swings were (176*F to 182*F) which is good for my purposes. I'm happy to report Saturday was a great brew day with no issues!

brewsme said:

So after changing the element from a 5500w to a 4500w I recalibrated the PID using the auto tune feature and this eliminated the temperature swings! :rockin:

When doing the auto tune I put the system (valves) in sparge mode, set my gpm to .25, and set the set point on the PID to 180*F. Once the temp reached 180*F I started the auto tune by switching At=2 and let it run until it stopped flashing on its own. During this time there where huge swings (130*F - 186*F). After the auto tune completed the swings were (176*F to 182*F) which is good for my purposes. I'm happy to report Saturday was a great brew day with no issues!

Click to expand...

One more thing, I'm not sure I needed to lower the wattage of the element and I didn't see the need to switch it back to a 5500w to find out since everything works smoothly at this point.