need some advice on DigiQ

Tennisbum · July 2010

Yesterday I did a brisket. Had the egg up to 225 dome. Attached the DigiQ and set the pit temp to 225 and the food temp to 185. All seemed well. The DigiQ kicked in and before I knew it the pit temp was 247 and the darn thing kept alarming. The brisket temp went to 165 in no time however it did stall at 170. What did I do wrong?
Thanks
gp

Mike in Abita · July 2010

You may have had the vents too far open. The natural draft of the egg with vents set open will overshoot the setpoint of the Guru. I usually try to close the daisy fully and set the fan damper to half open.

Did you notice if the fan was coming on when you were above your setpoint?

Did you connect the Guru to a cool egg? If so then that may have been part of the problem also. The further away from the setpoint your temp is the more the fan will pulse to raise the temp. Once it gets near the setpoint it shuts off, but by then you have too much lump lit and the temp will climb past. I will normally let my egg stabilize with the pit probe connected and the Guru shutoff. Fan out of the EGG and daisy removed untill I get to 200-225. Once there I connect the fan to the lower draft door and turn the unit on. On goes daisy, and set to close. Fan may pulse on and off for ten minutes until temp is at 250.

BobS · July 2010

There is nothing inside the fan to keep air from being pulled through with the natural draft inside the cooker, so you need to keep the top vent closed.

I have the 10 cfm fan and run it 1/4 open on my large.

Rolling Egg · July 2010

Im my experience, I have noticed that it's better to light the egg and go ahead and hook up the Digi Q and let it bring the egg up to temp. This is the way I do it every time and have no issues. There is tons of people that will chime in and back me on this. If you get your egg to 250 and hook up the Digi Q and set to 250, It's going to have a little spike in temp before it realizes to stop the fan completely.

Eggtucky · July 2010

Why did you get the temp to 225 before you put the digiQ on?.. you should light the egg with the digiQ already set and running...the lag time it takes for the Q to realize you are already to temp allows the fan to run, this heats the coals further and causes the Q to overshoot the temp...same thing happens if you are using the Q to maintain a cook and open the lid..if you don't close the damper on the Q, the fan runs since after opening the lid it sees a lower temp and is trying to catchup, this extra run time of the fan heats the lump further and causes the temp to be overshot...

Rolling Egg · July 2010

Also, like Bob said, I run my daisy completely closed because I have a few bad places in my gasket that lets enough air push out to hold 250. If you have a new tight gasket I would run my daisy just cracked enough I could slide a toothpick through barely.

rzrrob · July 2010

Rolling

Do you keep the daisy closed also?

Rolling Egg · July 2010

Yes. To hold 250 I keep the daisy completely closed. I have a couple bad places in my gasket that lets air come out fine. The Digi Q will take care of itself. It will push air out somewhere. The only time I have cracked my daisy to hold 250 Is when I'm running a new gasket with a tight seal.

Tennisbum · July 2010

Thanks for all the help. Nope I did not have the daisy wheel closed. Now that makes a lot of sense to me. the gasket is just about shot and needs to be replaced. so I will do that for sure in the future.
thanks again

brisket did taste ok but not great. I will continue to work with the digiq.
gp

Grandpas Grub · July 2010

NMSG

Grandpas Grub · July 2010

There are a lot of good comments above.

When I have a problem with heat, too high or too low, I always check the lump to see if there is enough then I begin to think about the air flow. That works with or with out a powered vent system like the DigiQ.

I've had my DigiQII since they were first brought out by the Guru folks.

When I use the q2 or Stoker I light the lump as I normally do with a powered vent system. About 50° before target temperature I install the blower and turn on the q2 (or stoker) and let the q2 finish bringing the egg to temperature.

On the q2 the blower has a damper which when the blower is in the off cycle it will allow free air to pass through the blower into the egg.

Think about your settings at 250° without a powered vent system. I would think your lower vent would be open no more than 1/4" and probably 1/16" - 1/8" (on a large egg) with the DFMT slider closed and petals open maybe the with of a flat tooth pick.

When the q2 blower is attached if the blower damper is not restricted and there is very much of an opening of the DFMT the heat will overshoot target temperature.

I have the Viper blower (10cfm)on the q2. The gaskets on my large are old and leak quite a bit. I close the blower damper to about 1/4 (below the 1/3 mark on the blower slider). I do leave the DFMT slider closed and petals open about the width of a flat tooth pick. With those settings on my large the q2 will maintain as low as 190° even with the old gaskets.

Before understanding this I was always fighting overshooting temperature with the q2.

The stoker blower has a gravity flap door which closed off the free air flow. I use the same DFMT settings as I do when using the q2.

When you open the dome and the dome will be left open for a time, make sure the dome open option is functioning on the q2 (or stoker) or simply unplug the blower cable from the power source. If the dome is opened for very long after shutting the dome do not plug in the blower for about 5 to 10 minutes.

Watch how you light the lump as any powered vent system will not recover from a vertical lump burn.

Hope this explanation will help you in using the q2 better.

GG

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