Brand New Damper Design - "The Micro Damper"



TVWBB Member
Thanks for this design, the jack was a little tricky to get in, but it worked great once I got it. I like to solder a little piece cat5 wire to the end if the fan and servo wires so they punch down better.
good idea! Mine didn't punch down in the block well enough at all to make any contact, so had to do some ugly modding lol

John Maloney

New member
My fan finally arrived and had a few tested cooks on my WSM 18. It seems to work best with the top damper 1/4 open. When I increase to 1/2 open I struggle to get the temps back down. What are others doing? Also I have been trying different pids and adjusting. I seem to get it right than a few hours later I get oscillation. If some one could provide their PIDS that work for them, that would be great. Thanks


TVWBB Member
Hello all, I need help. I purchased this damper back in 2015 for my Vision Classic B. I've always had issues with it maintaining the temp while using the micro damper. Sadly I have better luck not using it. I do know a year after I purchased this, Steve upgrade the fan that's in mine. I'm very frustrated with it and would like it to work. Wonder if I should start over with this project.

Yesterday after I smoked a meatloaf, I dug out the damper to try and get it to maintain 225. I played around with my PID settings, but didn't see any improvement. I let it run over night and it did as expected and put the fire out.

Attached are pictures of coal basket this morning, my damper setup, heatermeter activity when I put damper on (I took pit temp sensor out at 9am, now its just reading ambient temp), and PID settings.

I use a charcoal chimney to start a 1/4 chimney of coal. I pour that in the middle and then surround it with fresh charcoal. I buildup the fire to 300, then dial it back till it gets where I want it.

Any advice you can provide would be great.


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TVWBB Member
@RWilloughby how windy was it? where do you set the vent at the top? it looks to me that you may have ran low on fuel but hard to tell since there's no before pic. it could have also gone out due to piling fresh on top. That graph looks like loss of fire to me... I fill mine (green egg, same style grill) and light the top center of the pile with a hot air gun. you shouldn't let your grill overshoot, aim for 225 and maintain until the ceramic seems like it's warmed up. unless it's windy or not holding temp, the top vent should be wide open. you might still need a new fan, one with insufficient static pressure seems to underperform, especially when there's a breeze. Mine tops out at about 300. I love it for low & slow cooks but it struggles when the weather is not ideal. I'm planning on changing my fan too. I left my PID settings alone, they are stock.


TVWBB Member
The way you are necking down the output of the damper will definitely cut down the output with such a small fan. I also don't understand why you have the max fan output set to 40%. Maybe try setting it to 100. Seems like you are not getting enough air and fire is going out, or you ran out of fuel. Can't read the time scale so not sure how long this is going.


TVWBB Member
@KeithC - My top vent was 1/4 of an inch open. I would think having the top vent all the way open would make it uncontrollable? I'll put my hot embers on top of my coal, instead of under and see how that does. The damper is superglued shut so it will be hard to see what fan I'm using. I'll also go back to the stock PID settings.

@GSpinelli - I agree not enough air is getting through. My max fan output has been all over troubleshooting this. I'll bump it up to 100% and see how that does. I haven't done that in a while. For connecting to my grill, what are your suggestions? Should I remove the 2 pieces and find 1 to remove the step downs? That plastic fitting is superglued in so it might be futile.


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TVWBB Member
@RWilloughby that's closed down too much you need to open it up because you're not getting enough air like @GSpinelli stated. air in the bottom, exhaust out the top. If you don't vent the top, you won't have airflow and the fire will go out. top vent should be wide open to start and adjust from there. it's just like a car, you block the exhaust, the engine will die. same thing here really. it won't be uncontrollable because the fan & HM control the air going in, which controls the grill's temp.

Bryan Mayland

TVWBB Hall of Fame
You might also try setting the damper "fully open at" to 50% and the fan's "on above" to 50%, which makes the damper open fully before the fan comes on. That makes the fan more effective since it only runs when airflow is not restricted, and the time when it doesn't need it more gentle by only using natural convection through the open damper. The little fan isn't super powerful but it gets the job done on my egg no problem, however the extra restriction from the smaller tube might make it a little less effective, so having the outputs staged like this will help make it more consistent in output and linear in response.