Rims temp tube v mash

[immuneone]

I've constructed a rims system and have made several batches of brew. All have come out well albeit a bit inefficient. I have my pid set temps for either step brewing or single conversion. The tube keeps the temp in the tube spot on. The cooler (mash tun) is always about 10 degrees cooler. Is this "normal"?
Thanks

 

[stlbeer]

What are you using for a mash tun? Is it insulated? Are your thermometers calibrated and indicating the correct temp?

A couple of degrees off is one thing, but 10 degrees is too much in my opinion.

 

[cfrazier77]

I use a cooler and I don't have this problem. A couple of things come to mind.

I use the RIMS tube to preheat my mash tun, it heats up the metal tube too.

I calibrated the temp probe with an accurate thermometer. If the thermometer that you are using to take the mash temp does not read the same as your sensor for your pid then you will always have a problem.

One last thought, my tun is a 10 gallon drinking cooler. I get less temp swings when I put the lid on.

 

[immuneone]

I didn't think to check the calibration of the thermocoupler or the temp gauge ( duh). The mash vessel is the 10'gal igloo cooler modified with a false bottom.

 

[cfrazier77]

It happens, I realized how much of a factor this is when I had the same issue after building my RIMS tube. I had been brewing for years and all of my thermometers were off by different amounts. My two handheld ones differed by 6 degrees. The dial ones mounted to my boil kettle and HLT were both off.

I bought a scientific glass thermometer, 18" I believe, from Amazon for around $10. I used this to calibrate all of my thermometers and the sensor for the RIMS tube. I had to adjust it by 4.3 degrees. For my handhelds I sharpied how much they were off at 150 degrees. Not to long after this a got a thermapen. But for consistence, it helps if all of your temp measurements are the same.