Can't get RIMS to autotune

[BBBF]

I have a DIY RIMS tube, made out of tri clamp parts, with a thermowell near the return side of the tube. I can not get the the pid to autotune. It is a Cal 3300, not an Auber, but I have seen a few references to issues also tuning to an Auber. If this is a universal issue, what has everyone done? Did you find a way to make it work or just set it manually?

 

[augiedoggy]

I have a DIY RIMS tube, made out of tri clamp parts, with a thermowell near the return side of the tube. I can not get the the pid to autotune. It is a Cal 3300, not an Auber, but I have seen a few references to issues also tuning to an Auber. If this is a universal issue, what has everyone done? Did you find a way to make it work or just set it manually?

as long as the flow is consistent and closed loop you should not have an issue (according to common sense anyway) my mypin pid /rims had no issues with this...

 

[BBBF]

That is what I would think, but real world application seems to say otherwise. And I did autotune my other PID to the boil kettle, so have one point to compare.

 

[trimixdiver1]

Is the temperature crossing your set point and cooling back down? Usually to tune a PID loop the controller will drive the output across the set point like 3-5 times, may take a while, but if your output isn't doing anything or if it just stays at 100% and never goes lower then there is an issue with your probe or maybe the controller. Look at eBay for a nice watlow controller.

 

[BBBF]

It would cross the set point, take hours cooling down and never start heating up again.

 

[augiedoggy]

Well my cheap mypin td4 was able to autotune... I didnt need to autotune at all untill I increased my rims element to a 1800w 36" long element... now that I have autotuned it works better than ever. I have a low 2gpm flowrate when recirculating though which may help?

 

[BBBF]

I think I figured out the problem. I did a factory reset and started out with a clean slate. I think some of the settings remained from an earlier failed tuning, which made future autotuning next to impossible.

 

[BBBF]

By the way, where did you get a 36" element?

 

[trimixdiver1]

Cool, the PID probably don't reset to a default state on those, when doing a auto tune.

 

[augiedoggy]

By the way, where did you get a 36" element?

http://www.ebay.com/itm/390993852374?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Absolutely no carmelization or buildup on the element and the longer element ensures longer contact time so a better temp rise with gentle ULWD heat... I can get 2 degree rise per minute out of 5 gallons of liquid this way too...

pics are in my build thread at the end of the link below.