what am I doing wrong?


 

Mike Smith DFW

TVWBB Member
right now Im just using the P factor, and not I or D.

with my old iq120, it would blow the fan, wait a few seconds to a minute, activate the fan again, until temp was reached and it would basically maintain it.

with the heater meter, using the same air inlet as the iq120, when the HM shows low temp, it activates the fan, the temp cools a little, so it increases fan output, which cools temps a little more, which increases fan output.

Its basically a mess.

is it possible to have a pause in the output of the HM to allow the pit temp to start rising?

THANKS
 
Can you supply more details? What kind of smoker? what are your current fan settings?

Sounds like you have your max fan set too high, or pointing in the wrong place. Sounds like you're pushing all of the heat out of your smoker because of your fan settings, and where you may have it mounted.
 
that would be possible except the iq120 fan was mounted to the exact same inlet.

I did get a 15cfm fan and at 100% it was acting as a cooler and not a heater, so I have set it all the way down to 15% which is better.

I am smoking on a UDS. I stopped using that cooker because I was still having to go out and mess with it even with the controller.

I guess I could try a damper only solution but the iq120 worked fine as fan only.

edit: clarification- I dont have a working damper, so Im relying on just the fan,.
 
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It seems like the larger fan is just too much for the UDS. The logic can't really say "if it is getting cooler then lower or stop the output" because then it wouldn't work to maintain the temperature at all. It can't do any sort of running the blower then stopping to wait and see what the effect is, that's not how PID control works. The iq120 sounds like its algorithm has a minute long period and the output % is how much it runs the fan in that minute so it just sort of luckily works out because the control period is so long.

You could try setting a negative D parameter, which would lower the output if the temperature is dropping, but I think you need a lower output blower, or put a ball valve on your input to reduce it that way.

EDIT: But the PID logic is in grillpid.cpp
 

 

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