PID Airflow Issue On UDS

[medicbiff]

I have built a PID setup on my UDS.  I love my UDS and it does great on its own, however I must leave my smoker unattended often while smoking.  After some initial programming complications I think I am getting it dialed in and it appears to be working pretty well.  The issue that I am having is that when the fan is not running the drum is still drafting through the fan and the fire continues to build.  As a test, when my smoker temp was rising without the fan running, I covered the fan with a rubber glove to prevent the airflow and the smoker temp began coming back down.  What is the best way to build some sort of damper or flapper that will help prevent this.  Here are pics of my setup below:

Fan:

fan.jpg

• medicbiff
• Jun 16, 2015

PID control Box:

PID.jpg

• medicbiff
• Jun 16, 2015

 

[radioguy]

You could get a solenoid valve the same voltage rating as the fan. Wire it to open when the fan kicks in. Be mindful not to exceed PID output rating.(fan + solenoid watts).

Or just try to elevate fan assembly and lengthen the draft pipe. Maybe the longer column of cold air will lessen the draw when fan is not running. This is just a guess on my part.

RG

 

[daveomak]

You could get a solenoid valve the same voltage rating as the fan. Wire it to open when the fan kicks in. Be mindful not to exceed PID output rating.(fan + solenoid watts).

Or just try to elevate fan assembly and lengthen the draft pipe. Maybe the longer column of cold air will lessen the draw when fan is not running. This is just a guess on my part.

RG

Very simple and great idea.....