So with my RIMS system happily circulating, where should I check the temperature? The wort coming out to the pump inlet? In the grain bed somewhere? Also, what about accuracy of all the thermometers? I buy countless digital thermometers to calibrate my equipment, but how do I know the accuracy? If we are talking 153 degree mash temperature for instance, I don't want close enough at 155.
RIMS system temperature sample
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you need to put the probe going into the wort, it will be lower coming out thats normal, its up to you to set it higher or not, I personally don't, some people split the difference out and in, eventually it all catches up thats why I don't
processhead
Well-Known Member
I have the temperature probe located down stream of the heater element in the liquid line where it enters the top of the MLT. Others may disagree with this location for the temp probe, but it has worked well with my system.
The goal is to maintain the temperature of the mash, and also respond properly to set point changes. Almost any location will work to maintain a constant temperature. But not all probe locations will give optimum responsiveness when a temperature set point change is made. The location of the probe can significantly impact the response time and overall responsiveness of the PID when temperature set point changes are made.
The goal is to maintain the temperature of the mash, and also respond properly to set point changes. Almost any location will work to maintain a constant temperature. But not all probe locations will give optimum responsiveness when a temperature set point change is made. The location of the probe can significantly impact the response time and overall responsiveness of the PID when temperature set point changes are made.
The best place for the temp probe that drives the controller in a RIMS system is 1/4" - 1/2" from the tip of the heating element at the exit end of the RIMS tube. This maximizes system responsiveness (minimum lag time), and minimizes the the possibility of overheating the wort due to differences between the measurement point and the hottest point in the system. You may also want to install probe(s) in the bulk of the mash so that you can measure the temp deltas in your system.
Brew on
Brew on
Wizard_of_Frobozz
Well-Known Member
The best place for the temp probe that drives the controller in a RIMS system is 1/4" - 1/2" from the tip of the heating element at the exit end of the RIMS tube. This maximizes system responsiveness (minimum lag time), and minimizes the the possibility of overheating the wort due to differences between the measurement point and the hottest point in the system. You may also want to install probe(s) in the bulk of the mash so that you can measure the temp deltas in your system.
Brew on
I agree with this for the probe that controls the heater. I have mine set up this way and it works well.
I also have a thermometer on the outlet of the mash tun that I monitor (but it doesn't control anything). That helps me see the difference between the actual mash temperature and the heater outlet temperature. It's really useful when doing a step mash (or just raising up to mashout temperature); you know you have reached the next temperature when the two probes agree with each other.
I considered putting the probe directly into the mash tun but I decided against it; putting another hole in the mash tun didn't seem worth the trouble; measuring the tun outlet temperature works pretty well for this purpose and is easy to install into the piping.
augiedoggy
Well-Known Member
Ditto. besides being safer and less likely to scorch or explode if theres a flow issue you also get real time response and control which is always better to prevent overshooting. if the system is designed correctly it shouldnt perform any better with the temp probe at the inlet of the mt. If it does than something else is likely off like the flow being too high causing very inconsistent liquid temps as it leaves the heat exchanger tube (and equalizing in the hose before reaching the mt sensor)..
Putting it at the exit of the mt can cause a large overshoot because the element will be on 100% until the overheated liquid travels all the way through the grainbed which should take a couple mins at least. if this doesnt happen than your rims is functioning extremely inefficiently and not able to do much heating on each pass... the system will work but for other benefits like less channeling and less likely to have stuck sparge problems, the flow speed should probably be reduced. more is not better in this case. I average 86% efficiency with a mere 1.5-1.8 gallons per minute flow rate on my inline flow meter.
Dont forget to calibrate your temp probe
I brew 11gallons at a time on my system with an uninsulated mash tun and use a long rims with a mere 1800w element... when maintaining a mash temp of 151 the highest power percentage my pid every reaches during the whole mash is 21%... I can also step mash at just over 2 degrees a minute rise... many people with shorter 5500w elements still cant seem to accomplish this without problems and I believe probe placement , rims element length and flow speed all are contributing factors.
I should add that I experinted with 4 different rims tube configurations and lengths while tweaking each one for better performance and found it was longer contact time on each pass that makes the most difference not element wattage. the 1800w element I have now outperforms the 2000w element it replaced because its 1 ft longer. The other benefit is theres zero buildup or chance of scorching on the element plus since my flow level is so low I have never needed rice hulls or had recirc flow problems (and I use a tiny p38i $18 pump which could plug easily)
Definitely measure wort temp directly downstream of the heater. That helps prevent wort overheating and premature enzyme denaturing. Don't worry about the temperature of the mash bed. It will reach your desired wort temperature eventually. It takes time for the 'wave' of hot wort to work its way through the bed.
Wizard_of_Frobozz
Well-Known Member
Augiedoggy is correct that if the system is designed correctly, it shouldn't matter. As he points out, things can get "off" pretty easily. It's been my experience that the nature of homebrewing is too inconsistent to have a "correctly designed" system because what works for one type of beer doesn't for another. Consider this:
Brew Session # 1: a low gravity session ale; 8 lbs of grain and a water to grist ratio of 1.25 qts/lb. You carefully tuned your PID controller with water ahead of time, and everything works pretty well.
Brew Session #2: a Barleywine; 16 lbs of grain and a water to grist ratio of 1.00 qts/lb because you can't fit it all into the mash tun with a higher ratio. Now your carefully tuned PID burns your wort. What happened???
Your system was tuned for very little grain and a lot of water. It worked ok as long as the beer you brewed was close to that. With the Barleywine, the higher amount of grain combined with relatively less water means flow rate was a lot lower. The higher sugars in the fluid burned on the heater because it was tuned for a higher flow condition.
Our processes change too much from batch to batch to be able to have consistent temperature control if the control probe is measuring the mash temperature directly. Putting the probe just after the heater makes the system able to respond almost immediately to changes, and this minimizes the impact of the the differences between batches.
I'm direct fire RIMS and believe principal is same although I'm not able to use PID mode on my PID...solenoid is on/off only. I measure at outlet of recirc pump with RTD sensor. I don't worry about mash temperature at any other location as I am only designing my recipient to be repeatable by me on this system. If I were brewing pilot batches intended to be scaled up to a larger system I'd want to track temperature in at least the mash as data for, although I'd still drive the burner from the same spot to avoid risk of overheating the wort.
augiedoggy
Well-Known Member
This is why tuning EVERYTHING for the lower flow rate works best IMO. This way if its a barely wine or a pilsner you still have the same or close to the same flow rate and the same pid values still apply... I find that my flow rate varies between 1.2 to 1.8 gallons per minute depending on grist/ and adjucts as well as grainbed depth so I tuned my pid at 1.5gpm flow and I have no issues at all with my rims.
