RIMS system woes

so i have my direct fire RIMS system almost where i want it but im still running into a major issue. I thought consulting the brain trust here before i go on a mission later today to fix things before brew-day Sunday would be wise.
I use a BCS-462 to control my entire brewery (full equipment write up here)
The issue is when i heat my strike water my blichmann thermometer and BCS temp. probe do not agree. Last brew-day i heated my strike water according to the blichmann analog thermo and i WAY overshot my mash temp. I usually end up going over on my mash temp and the 2 thermo's never agree, so far i have been using the BCS probe to control the mashing process but trusting the analog blichmann thermo for my temperatures. (basically i let the BCS think i want to mash at say 160 when im mashing at 155 according to blichmann)
On the agenda for today is running a new wire to my BCS temp probe to eliminate crosstalk from other wires, and to check both thermometers with 2 analog ones (picking up from the LHBS when i get ingredients)
One issue i have is i cant run boiling water through the RIMS system or i will destroy my flow rate meter, so can i do the thermo test with say 150* water ?
Any of the experts on RIMS systems here have any other ideas ?.
Thanks HBT

I trust my PLC reading over my Analogue therms, and test against the readings with a lab stick thermo mid mash column. Then I adjust the analogue to agree.

Maybe part of my issue is i feel like i should be measuring my center grain bed temp not the temp of the recirculating wort. The analog thermonator measures center grain bed and the BCS probe measures recirculateing wort

Can you back off the font size in your sig a bit?

The analogs are a ballpark measurement at best. I sell analog thermos and I'll admit that. You should grab a handheld digital to double check things. Have you ever put the blichmann in a pot of boiling water to see what it says? How about the BCS probe?

Dump the analog or tee in a temp probe...

Most analog can be calibrated using a salt water ice bath, I'd give that a try and see if that helps.

Most analog can be calibrated using a salt water ice bath, I'd give that a try and see if that helps.

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To what temp?

Put your probes & thermo close together in a container of water along with a digital hand held thermo (like a CDN) and test away. I have a BCS and a BlichPieceofcrap thermo and the most accurate of all the devices is the CDN $15 digital thermo. I can take the CDN to the ice water bath or pot of boiling water and be dead on accurate, none of those other devices are nearly that good. The one thing I hate about the BCS is the thermister probes, they just don't compare to the RTD's you can get from Auber to use with the PID.

Best bet if you are able is to try and calibrate the BCS probes to near the ranges they will be used at. So for a MLT or RIMS you obviously want to be accurate between 150-170F. btw - I pulled out the last of my hair trying to get this done and finally learned to live with the inaccuracy of it all.

mcl said:

To what temp?

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By using an ice bath you'll be calibrating it at 32F/0C. Here's a good link:
/www.ehow.com/how_5287987_calibrate-dial-thermometer.html

I have almost the exact same setup. I use the Blichman. when I'm heating the water for the HLT and recirculating 180 degree water the digital probe and blickman analog are almost always in agreement. When I put grain in it and mash the probe is a little hotter. (The probe is measuring the water coming off the bottom of the kettle so its going to be warmer)

I have used this setup for almost 2 years and I get consistent results. Short of constantly stirring your mash while you recirculate I doubt your ever going t get the center bed temp and the word coming out of the bottom to match up exactly.

So I really dont need to worry about the blichmann thermo ? I know my grain bed temp will motzerlla be constant due to hot spots and what not. Should I just check my calibration on my BCS probe and use that as my only control point. What it comes down to is I feel like I should be measuring the temp of the grain bed rather than the wort coming out of the tun.
In short I'm asking which is correct/ where I should be looking to make sure I'm hitting my mash temp ?
Thanks for the responses

Measure the wort exiting the RIMS to control the BCS. Measure the actual grains as a checkpoint to see how effective your set up is. I routinely found that I needed to be 1-2F higher on my set point to keep the mash temps correct.

I have a similar issue.
I calibrated my bcs probes, the blich thermo and a digital thermo in 3 different temp ranges. All of the in a container of water were very close.
BUT, the readings on the blich thermo in hte middle mash, the digital thermo stuck in the top of the mash, and the bcs sensor measuring the wort flowing from the kettle to the rims tube, are all very different. sometimes more than 10 degrees.
I have a bcs sensor at the top of Derrins rims tube to control the bcs, but hav no idea which of the other readings to use as THE mash temp.

UPDATE: so i brewed an IPA yesterday and I decided to go crazy and run a another temperature probe and measure the middle of the mash (required a bit of customization but worked well) additionally I monitored my RIMS output, blichmann thermometer and used a handheld digital lab grade thermometer.
This method worked MUCH better, my RIMS output always read 10 deg higher than the mash reading, however, with the strike water the two BCS probes eventually came into perfect agreement (actually all thermometers did) but the addition of grain threw some variables into the system. I missed my mash temperature by 2*F when mashing in but it cooled and when I averaged all my readings I only got a .5*F high reading, so not too bad there.
I think my next upgrade is going to be putting 3 temperature probes into the side of my mash-tun and controlling the mash by averaging the temperature readings from the 3 probes.

Consider an auto mash stirrer to equalize everything if the temperature stratification is an issue for you. You can build one really cheap with leftover parts.

HollisBrewCo said:

I think my next upgrade is going to be putting 3 temperature probes into the side of my mash-tun and controlling the mash by averaging the temperature readings from the 3 probes.

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I have a Brewtroller and average the output of my RIMs and one temp probe in the mash tun. I will eventually add a third probe and place it the the mash also and average the three. I can see the two temperatures independent of each other and the RIMs output is always 6-10 degrees higher.

pickles said:

I have a Brewtroller and average the output of my RIMs and one temp probe in the mash tun. I will eventually add a third probe and place it the the mash also and average the three. I can see the two temperatures independent of each other and the RIMs output is always 6-10 degrees higher.

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Does the Brewtroller do this, or do you manually average the output temps? And are you saying you intentionally set your RIMS set-point that much higher to account for the actual grain bed temperature? I've always set my PID for the mash-temperature called for in the recipe and let 'er roll. I have a seperate digital thermo probe stuck in the upper part of the grain bed, and eventually, the two jive. I'm not exactly sure how to handle temperature stratification with a RIMS, just as I was not sure how to deal with it with a traditional mash.

I measure the wort coming out of my MLT with the BCS and the Blichmann thermo measures in the middle of the grain mass. With the MLT doing continous recirculation, they usually agree within a degree or two. When the burner fires though to raise the temp, the wort will spike higher than the grain mass until they equalize after some recirc time.

Reelale said:

Does the Brewtroller do this, or do you manually average the output temps? And are you saying you intentionally set your RIMS set-point that much higher to account for the actual grain bed temperature? I've always set my PID for the mash-temperature called for in the recipe and let 'er roll. I have a seperate digital thermo probe stuck in the upper part of the grain bed, and eventually, the two jive. I'm not exactly sure how to handle temperature stratification with a RIMS, just as I was not sure how to deal with it with a traditional mash.

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The brewtroller does the averaging. It has a feature that can be enabled the will average up to 3 temp inputs to control mash temperature. I can flip to another screen that shows "Aux temps", Aux 1 is my RIMs output. It usually reads higher, I shouldn't say always. I don't always look at that screen but I have noticed it being much higher. I have since thinned my mash from 1.25 qt/gal to 1.5 for a few reasons and that has narrowed the margin.
I will pay closer attention next time I brew.

Consider an auto mash stirrer to equalize everything if the temperature stratification is an issue for you. You can build one really cheap with leftover parts.

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Thats going on the update list I know traditional RIMS theory says to put the control point on the output of the system closest to the heat source but my temperatures seemed to be much more accurate and stable measuring the center grain bed. I may also do a temperature probe at the wort return point but im not convinced its necessary. I just like data

vfinch said:

Most analog can be calibrated using a salt water ice bath, I'd give that a try and see if that helps.

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Salt water ice bath is a bad idea. That would drop the temp below freezing.

Thoroughly crushed ice plus water is what you need for a 32° F / 0° C calibration.

Or calibrate at boiling. 212° F / 100° C.

Agreed, when I was working in a lab build temp probe for environmental studies thats how we checked the probe.

Crush ice (a lot, you actually cal in ice, water is there to fill the space between ice shunk), distilled water, mix well, push the probe in the mix to actually puch the ice down, but not it the bottom.