BBQ Guru fan froze

Jeepster47

bigalsworth said:

I think part of the problem will be using a flapper light enough to open (may need to adjust the guru fan gate a little wider open) but also be strong enough to take the heat inside the egg.  Will the flapper open all the way or will it matter if it doesn't?  I would think that the algorithms should be able to compensate based on the fact that it just turns a fan on and off based on temperature rising and falling.

It would be hard to say if the egg can limp along with a power outage.  With the right flapper (weight) it might, the natural draft may have just enough oomph to slightly open the flapper, especially if you need to open the guru gate a little more to get desired results.

edit: maybe with the downward leaning of the adapter the flapper will hang slightly open when there is no positive pressure in the egg

My assumption has been that the flapper is just strong enough to restrict the natural airflow to almost zero ... and, not restrict the airflow when the blower is functioning.  @NPHuskerFL was kind enough to send me some pictures of the Stoker flapper, and that's what it looked like from the pictures.  If you're not going to greatly restrict the natural airflow, then why have a flapper?

I suspect you're correct on the algorithm being able to compensate, but you never know with those IT engineers ... they're really a weird lot.

The adapter leans downward as it exits the egg and the Stoker flapper uses that angle to hold the flapper "tight."  If the flapper is mounted on the egg side of the adapter plate, then it should also be closed in it's natural state.  You could "tune" the flapper to the correct on/off functionality by using heavier or lighter flapper material.  I think it could be made out of brass sheeting from Ace or a hobby store which has various thicknesses of brass.

bigalsworth

Jeepster47 said:

bigalsworth said:

I think part of the problem will be using a flapper light enough to open (may need to adjust the guru fan gate a little wider open) but also be strong enough to take the heat inside the egg.  Will the flapper open all the way or will it matter if it doesn't?  I would think that the algorithms should be able to compensate based on the fact that it just turns a fan on and off based on temperature rising and falling.

It would be hard to say if the egg can limp along with a power outage.  With the right flapper (weight) it might, the natural draft may have just enough oomph to slightly open the flapper, especially if you need to open the guru gate a little more to get desired results.

edit: maybe with the downward leaning of the adapter the flapper will hang slightly open when there is no positive pressure in the egg

My assumption has been that the flapper is just strong enough to restrict the natural airflow to almost zero ... and, not restrict the airflow when the blower is functioning.  @NPHuskerFL was kind enough to send me some pictures of the Stoker flapper, and that's what it looked like from the pictures.  If you're not going to greatly restrict the natural airflow, then why have a flapper?

I suspect you're correct on the algorithm being able to compensate, but you never know with those IT engineers ... they're really a weird lot.

The adapter leans downward as it exits the egg and the Stoker flapper uses that angle to hold the flapper "tight."  If the flapper is mounted on the egg side of the adapter plate, then it should also be closed in it's natural state.  You could "tune" the flapper to the correct on/off functionality by using heavier or lighter flapper material.  I think it could be made out of brass sheeting from Ace or a hobby store which has various thicknesses of brass.

well you have the flapper not to restrict natural airflow but to restrict blow back due to a pressurized egg, isn't that what we are discussing?  the flapper will work on differential pressure between the guru adapter and the egg, so on either side of the flapper.  the fan needs to overcome the effect of gravity on the flapper to open it and then, with the cap probably mostly closed, the egg will slightly pressurize.  When the fan cuts out the pressure will drop causing the pressure inside the egg as well as gravity to close the flapper and hold it there until the pressure equalizes to atmospheric through the top vent (or other leaky areas) at which point only gravity will be holding the flapper down.

yeah you are right it leans downward so the flapper would sit completely closed, I was confused.  And natural draft likely will not be able to lift the flapper.

I might also look into this myself,  mild steel is a little less dense than brass and might work as well, you may be able to make it a little more robust for the same weight, but access to materials is definitely a large factor

Jeepster47

@bigalsworth ... there's the concept where we diverge.  Most folks control a manual cook by adjusting the bottom vent.  With a flapper to restrict natural airflow, it's not unlike a manual cook except that the blower becomes the "door open" setting.  If that's true, then the top vent could be opened more with a flapper in place ... less back pressure.

@NPHuskerFL ... you have a Smokeware cap ... how open do you set your cap when running the Stoker at 250*?  Or, anyone else know their settings with the Stoker at 250*.

bigalsworth

Jeepster47 said:

@bigalsworth ... there's the concept where we diverge.  Most folks control a manual cook by adjusting the bottom vent.  With a flapper to restrict natural airflow, it's not unlike a manual cook except that the blower becomes the "door open" setting.  If that's true, then the top vent could be opened more with a flapper in place ... less back pressure.

@NPHuskerFL ... you have a Smokeware cap ... how open do you set your cap when running the Stoker at 250*?  Or, anyone else know their settings with the Stoker at 250*.

I see what you are saying, then we will not be able to call it a check valve and won't sound as cool