RIMS exit temp vs mash temp

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logdrum

logdrum

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OK, so this is just from a preliminary water test with my EZ Boil controller, but when I ran a recirculating trial (tap water in my Spike mash tun, to a chugger, through a RIMS Rocket, back to mash tun) the temp probe at the exit of the RIMS Rocket read 133ºF (my set point) but the water in the mash tun (measured with a Thermapen) was at 122.xºF. I am a total RIMS newby, so I'm curious if this behavior will carry over to a real life mash, or will the thermal mass of the grains alleviate the offset? Thanks in advance!
 
How long did you run it. The rims is not for heating the mash it is for maintaining temperature. If you got the water in the tun to 133F it should hold it there. Given time, and with the small amount of heat to water contact it would take a long time, the temperature should equalize.
 
Thanks, I was thinking as much; I plan on gas firing for my strike water, but wanted to be able to do a mash out w the RIMS. Is this not feasible?
 
You can use the RIMS to heat as long as the element is powerful enough and your flow rate is sufficiently high. I do it every single time on my electric system.
 
Well, it's the 110v model, so that might be an issue, I'm just trying to work through logjams so the first brew on the new system isn't a complete nightmare.
 
Actually I am wrong about just holding the temperature. They are often used for step infusion mashes.

You say the tun temperature was 122 and the rims was 133, and it was run for 20 minutes. Was the tun temperature 122 at the start?

If you want to do mash out. You will need to raise the temperature from about 150 to 170 relatively quickly. If it will not do that you will not be able to use it for mash out.

Are you doing a fly sparge? If you are batch sparging you don't have to do a mash out.
 
No it was 88, I just did a quick trial before work, so this is all preliminary stuff, plan on continuing with batch sparge
 
logdrum said:
No it was 88, I just did a quick trial before work, so this is all preliminary stuff, plan on continuing with batch sparge
Click to expand...

If you went from 88 to 122 in twenty minutes, it should be able to handle step infusion mashes and mash outs. Insulation on the tun will help a lot if you don't already have some.
 
Do some tests with plain water first. Make sure your controllers are tuned and you know how to dial in your flow rate.

You can do a lot with 120V, especially with 5G batches. Over that you really need 240V.
 
I know how to tune a guitar, but how do I go about tuning the EZ Boil? Also what sort of flow rate should I look for-chugger pumps w ball valves
 
Great question @logdrum!

I just picked up a 120v RIMS as well... First brew I ran without a temp probe in the tube (don't do this).

I'm planning a second brew for Sunday (with a thermometer inline) and have some skepticism on tube temps aligning w/ the tun. Especially w/ insulation pockets that can occur in the grain..?

On my first batch (10 gallons), I was seeing temp swings as much as 6-8 degrees in the grain bed depending on where I placed my 24" ThermoWorks probe.
 
The temperature of the wort at the outlet from the RIMS heater is the thing you want to control. The temperature of the wort at the mash bed outlet will lag the heater temperature, but it doesn't matter nearly as much. If your system is well insulated, then its likely that the mash outlet temp will get to the heater outlet temp. Give it time.

Don't overheat your wort in a quest to get your mash outlet temp to your target temp.
 
mabrungard said:
The temperature of the wort at the outlet from the RIMS heater is the thing you want to control. The temperature of the wort at the mash bed outlet will lag the heater temperature, but it doesn't matter nearly as much. If your system is well insulated, then its likely that the mash outlet temp will get to the heater outlet temp. Give it time.

Don't overheat your wort in a quest to get your mash outlet temp to your target temp.
Click to expand...

I would agree. If you monitor the temp of the mash for your PID control, their will be an unavoidable lag time and there will be a tendency to overheat the the mash at the inlet side of the MLT until the temperature rises at the point where the RTD probe is monitoring temps. Same applies if you were monitoring at the outlet of the MLT, only an even longer lag time.

Wet testing your system with only water is OK, but remember the temperature rise time with just water will probably be different than a grain bed, primarily because the solution flow rate through the grain will be slower during an actual mash
 
mabrungard said:
The temperature of the wort at the outlet from the RIMS heater is the thing you want to control. The temperature of the wort at the mash bed outlet will lag the heater temperature, but it doesn't matter nearly as much. If your system is well insulated, then its likely that the mash outlet temp will get to the heater outlet temp. Give it time.

Don't overheat your wort in a quest to get your mash outlet temp to your target temp.
Click to expand...


So if I have a recipe with a mash target of 150, this needs to be the temperature at the outlet of the RIMS tube correct?

The reason I ask is I'm wondering if there's any value to overshoot a few degrees higher if the mash tun is not insulated...
 
No don't overshoot. Set it exactly where you need it. You need to recirculate the entire mash volume at least once over to raise the temp of the whole thing.

So you want the highest flow rate you can achieve in your system without sticking the mash. This is going to depend on your vessel, false bottom (or braid), crush, grain bed depth, etc. you can figure this out with trial and error but reasonably it needs to be between 2 and 6 quarts per minute.
 
What are the odds that my probe is reading higher than actual temps? I'll do an ice water test soon
 
Depends on the type of probe, but most electronic probes are accurate to better than a degree. Usually it's the wiring that adds an offset.
 
As part of any wet testing, I like to check calibration of the MLT temp probe at, or near mashing temperatures. That way, I know it is right.



Trying to compensate for system inaccuracies is a bad deal. You need to be able to trust what your equipment is telling you.

Calibrating in an ice water bath is ok as long as the temp probe characteristics are linear through its range. That is not always a given, though.

Testing and calibrating at mash temps with a good, lab grade thermometer or other temperature standard, assures that the probe is accurate in the temperature range you are concerned about.
Make sure your temperature standard is positioned in the same location as your temp probe so you don't introduce an error by measuring a spot in your MLT that is a lower or higher temperature.
 
I have a 120V RIMS tube for my keggle mash tun with a full false bottom. After mashing in I let the grain sit for ten minutes before starting to recirculate with my chugger pump. I'll start at half open and increase the flow over a couple minutes to full open. There is a temperature sensor at the RIMS tube exit to control the RIMS and an analog thermometer at the pump inlet.

Initially the RIMS temperature sensor is at (and stays within one degree of) the set point and the pump inlet thermometer reads five degrees lower. This pump inlet temperature increases over twenty minutes to one degree below the set point. The pump inlet temperature never reaches the set point, it is always one degree lower. I posted about this when I first got my RIMS tube and this is how most other systems perform.
 
CanAm said:
I have a 120V RIMS tube for my keggle mash tun with a full false bottom. After mashing in I let the grain sit for ten minutes before starting to recirculate with my chugger pump. I'll start at half open and increase the flow over a couple minutes to full open. There is a temperature sensor at the RIMS tube exit to control the RIMS and an analog thermometer at the pump inlet.

Initially the RIMS temperature sensor is at (and stays within one degree of) the set point and the pump inlet thermometer reads five degrees lower. This pump inlet temperature increases over twenty minutes to one degree below the set point. The pump inlet temperature never reaches the set point, it is always one degree lower. I posted about this when I first got my RIMS tube and this is how most other systems perform.
Click to expand...

I suspect your PID tuning may be causing what you are experiencing. One possible cause is if the error dead band is set at too large a value.
 
I have one DS18B20 probe controlling my RIMS and one in the middle side wall of a 15gal stainless mash tun (compression fitting). The mash tun probe is always 2deg F lower than my RIMS at equilibrium. I know the probes read exactly the same because I have put them both in the same liquid a few times. I use strange brew elsinore, which doesn't have auto tune function. I have used a few different PID settings that I have found on the web, and none of them seem any different. They all work fine. Unless it's way out of whack, this shouldn't make much difference.

I would be leary of comparing two different types of temp sensors, dial/digital/PT100/mercury. Unless you have a thermapen or a Fluke, it's just going to be a ballpark. Many of the cheap digital thermometers are +/- 2deg accuracy.
 
CanAm said:
I have a 120V RIMS tube for my keggle mash tun with a full false bottom. After mashing in I let the grain sit for ten minutes before starting to recirculate with my chugger pump. I'll start at half open and increase the flow over a couple minutes to full open. There is a temperature sensor at the RIMS tube exit to control the RIMS and an analog thermometer at the pump inlet.



Initially the RIMS temperature sensor is at (and stays within one degree of) the set point and the pump inlet thermometer reads five degrees lower. This pump inlet temperature increases over twenty minutes to one degree below the set point. The pump inlet temperature never reaches the set point, it is always one degree lower. I posted about this when I first got my RIMS tube and this is how most other systems perform.
Click to expand...


Full open?! What false bottom do you use? I also have a bottom draining keggle, and ended up with a stuck mash when I very slowly opened the pump all the way...

Edit:
After the stuck mash happened, I followed up on the chugger pump flow rate which came out to 7 gpm! This seems like overkill and maybe even harmful for a mash..?
 
golfindia said:
I have one DS18B20 probe controlling my RIMS and one in the middle side wall of a 15gal stainless mash tun (compression fitting). The mash tun probe is always 2deg F lower than my RIMS at equilibrium. I know the probes read exactly the same because I have put them both in the same liquid a few times. I use strange brew elsinore, which doesn't have auto tune function. I have used a few different PID settings that I have found on the web, and none of them seem any different. They all work fine. Unless it's way out of whack, this shouldn't make much difference.

I would be leary of comparing two different types of temp sensors, dial/digital/PT100/mercury. Unless you have a thermapen or a Fluke, it's just going to be a ballpark. Many of the cheap digital thermometers are +/- 2deg accuracy.
Click to expand...


I am using a thermapen to confirm temps
 
logdrum said:
Hmm, could you elaborate on the wiring issue? It's this probe from Auber:

http://www.auberins.com/index.php?main_page=product_info&cPath=20_15&products_id=249
Click to expand...

Auber aghh... i hate those fu(ktards. Worst company ever.

Anyways, they are just reselling cheap stuff from asia. RTDs are good because they are 3 wire connections. 2 of those wires actually form a feedback loop that is used to compensate for the resistance of the wire. Neat trick actually. As long as you use all 3 wires and connect them as they are designed no problem.

Thermocouples are a bit trickier. They work by having specific metal junctions and relay on the voltage created at the junction. However, you can create additional junctions by as simple as making an electrical connection, which adds an offset. The wire material has to match the junction material. They make special terminal blocks and connectors with matching metals if you have to break the connection.
 
That comment about waiting 10 minutes before starting recirculation is interesting. I start recirculation as soon as the grain is doughed in since I want to fully mix all the water with the bed and make sure the wort temperature is more uniform.

My tun has a manometer tube ported into the bottom so that I can monitor the head at the bottom of the grain bed. With that instrument, I have found that all mashes have low permeability initially and its permeability increases during the mash. I have also found that I don't create a stuck mash if I limit the head drawdown to about the bottom of the bed. If you don't have a manometer in your tun and you try to run the pump at too high a rate, you can pull a great deal of negative pressure on the bottom of the bed and that can compact the bed. Wide open is NOT a good idea in RIMS and HERMS. You should have a way to monitor the head at the bottom of the bed.
 
logdrum said:
What are the odds that my probe is reading higher than actual temps? I'll do an ice water test soon
Click to expand...


Your better off calibrating @150 with a good thermometer. If your mashing at 152 then 32 degrees is 120 degrees away. If you check it against a boil your 60 degrees away. Your really only concerned with a range of 113 to 170 with most of your time spent around 144-158. So that what your calibrating too. If your off by 2% your going to be ok but 2% of 120 is a lot more of a spread.
 
mabrungard said:
That comment about waiting 10 minutes before starting recirculation is interesting. I start recirculation as soon as the grain is doughed in since I want to fully mix all the water with the bed and make sure the wort temperature is more uniform.
Click to expand...

I've noted a similar issue before where if i immediately started to recirculate i'd always end up with a stuck mash. No amount of stirring ever seemed to fix it. I'd always have to dump the mash tun out and blast out the false bottom. If i waited 10 minutes and started slow it would settle the grain bed and start to clear within a few minutes.

More recently i've been underletting the mash initially, targeting 131F. The dough-in procedure takes about 12 minutes, and as soon as it's done, i stir it, put on the mash cap, and crank up to the first beta rest right away. In my 15G boiler maker G1 mash tun i recirculate at 1.5GPM. Even more recently i tried to maximize the amount of grain in the tun and above about 28 lbs I can't recirc above 0.9-1 GPM without sticking it.
 
I'm underletting about as fast as a 24V little tan pump will let me, and I can immediately start recirculating at about 20% of max flow rate. I bring that up to fully open in about ten minutes.

This is with conditioned grain and a domed false bottom. If there's wheat in the mix, I'll throw a big scoop of rice hulls in before putting the grain in and underletting.
 
mabrungard said:
My tun has a manometer tube ported into the bottom so that I can monitor the head at the bottom of the grain bed. With that instrument, I have found that all mashes have low permeability initially and its permeability increases during the mash. I have also found that I don't create a stuck mash if I limit the head drawdown to about the bottom of the bed. If you don't have a manometer in your tun and you try to run the pump at too high a rate, you can pull a great deal of negative pressure on the bottom of the bed and that can compact the bed. Wide open is NOT a good idea in RIMS and HERMS. You should have a way to monitor the head at the bottom of the bed.
Click to expand...


Just to be clear, the manometer is purely to monitor if the grain bed is compacting and preventing flow correct? I'm thinking of doing something similar, but using a vacuum gauge instead so I don't have to buy a more expensive false bottom or bother punching more holes in my keggle...
 
brewApprentice said:
Just the be clear, the manometer is purely to monitor if the grain bed is compacting and preventing flow correct? I'm thinking of doing something similar, but using a vacuum gauge instead so I don't have to buy a more expensive false bottom or bother punching more holes in my keggle...
Click to expand...


Yes a manometer measures the relative vacuum created under the mash bed. I'm not sure how you'd get a vacuum gauge to measure that unless it's placed under the mash. I sight gauge will show you the same thing to a certain extent.
 
As a follow up, I programmed an offset into the EZ Boil & it holds the (water) temp rock steady. Looking forward to the first RIMS brew!
 
brewApprentice said:
Just the be clear, the manometer is purely to monitor if the grain bed is compacting and preventing flow correct? I'm thinking of doing something similar, but using a vacuum gauge instead so I don't have to buy a more expensive false bottom or bother punching more holes in my keggle...
Click to expand...

I see this same effect with both my sight glass and my electronic volume measurement (via hydrostatic pressure sensor). Makes having a sight glass worthwhile.
 
Dcpcooks said:
Yes a manometer measures the relative vacuum created under the mash bed. I'm not sure how you'd get a vacuum gauge to measure that unless it's placed under the mash. I sight gauge will show you the same thing to a certain extent.
Click to expand...


Correct-- the vacuum gauge will go inline just upstream of the wort outlet flow valve on my bottom draining keggle. We'll see how it works in reality, but the idea is any suction pressure that would occur between the pump and a compressed grain bed, should display on the gauge indicating a vacuum is occurring and needs to be corrected for.

For now, I'm trying to avoid a sight gauge based on reasons already mentioned, and it's just one more thing to clean...

Still waiting on parts, but once it's setup I'll post pictures if anyone's curious.
 
dyqik said:
I'm underletting about as fast as a 24V little tan pump will let me, and I can immediately start recirculating at about 20% of max flow rate. I bring that up to fully open in about ten minutes.

This is with conditioned grain and a domed false bottom. If there's wheat in the mix, I'll throw a big scoop of rice hulls in before putting the grain in and underletting.
Click to expand...


Those tan pumps max out at just over 1.5 gpm correct?

If this is the case I way overkilled my first RIMS run with a chugger pump! No wonder I ended up with a stuck mash at 7 gpm [emoji13]
 

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