Fixed venting with a blower control

Jeepster47

Over the last year there has been some discussion about the lack of a damper in the Flameboss units.  Based on the growing pains I had with the Bubba Guru, the missing damper originally bothered me also.

The FB controls temp by forcing air into the bottom of the egg to overcome a top vent restriction.  If the fan doesn't operate, the correct top vent setting will drop the pit temp below the desired temp setting.  @stlcharcoal likes to set his top vent so that the FB runs a minimal amount of the time.  I prefer a top vent setting that makes the FB blower run, on average, about 25% of the time.  Both approaches work well, mine has a larger margin for error to correct for a flame up when the lump collapses during a long cook.

The main problem with a blower control is getting the top vent setting correct. If the blower never runs and the pit temp is just above your set point, then your top vent is set too loose.  If the blower runs 90% of the time and the pit temp skips along just below your set point than your top vent is too tight.  Since the top vent opening is very small it's easy for it to change from cook to cook.  Clean your top vent and, guess what, yep, your setting will be different on the next cook ... with either ugly daisy or Smokeware.  Because of that, here's an idea I've been playing around with:



It's simply a 1/2" thick plywood disk with a 13/64" diameter hole drilled through it.  It fits under ugly daisy or the Smokeware cap and provides a fixed restriction that doesn't change from cook to cook ... push a drill bit through it every couple of cooks and you're good to go.  I think the hole diameter needs to be changed to match the air leakage for each individual egg ... good felt line seal or bad.  Haven't had time to prove or disprove the need for a different size hole.

Here's my last baby back cook with this set up:



A little overrun on start up 'cuz I lit the fire, installed the FB, and walked away to prep the meat.  The first dip at 1:36PM is when the ribs were placed on the grid ... notice that the cold meat pulled the temp down to the set point. Sauced the ribs at 6:08PM and pulled them at 6:29PM ... did absolutely nothing else during the cook.

Notice the dip in temp at about 4:30PM and the rise in temp at about 5:20PM ... I'm guessing that that is the lump re-positioning itself as the center burns itself up.  The first time the temp dropped and the second time the temp flared.  Both times the FB reacted appropriately and quickly corrected the temp perturbation ... (love that word.)

A smaller hole will reduce the natural airflow and cause the fan to run more ... like wise, a larger hole will increase the natural airflow and reduce the fan run time.

If you've got the time, give it a try and see what you think ... please post your results though ... good or bad. 

RRP

Thanks for your research and effort, Tom. Makes for an interesting report and proven solution. I have to ask - how did you determine 13/64th would be the chosen size? That is such an odd number so surely you did come other calculation to settle on that.

fishlessman

what you have there is a mikeyt ring on steroids

ron, you might already have the right size

RRP

fishlessman said:

what you have there is a mikeyt ring on steroids

ron, you might already have the right size

LOL - nice to know my photo is in your scrap book! yes I still have those rings and they do work!

Jeepster47

@RRP ... calculations are good, but sometimes it's faster to simply cut and try.  I started with a smaller hole and gradually enlarged it until the results were acceptable.

@fishlessman ... Ron posted those on the forum a couple of years ago ... that's why one of the first snuff lids was made of wood.  Simply grabbed one of those and started drilling.  You'd think they would ignite, but they don't even char.

dougcrann

Teaching the wife how to use her Egg with the FlameBoss....this will come in handy...Thanks...

fishlessman

RRP said:

fishlessman said:

what you have there is a mikeyt ring on steroids

ron, you might already have the right size

LOL - nice to know my photo is in your scrap book! yes I still have those rings and they do work!

for some reason all the mikeyt ring pics from yesteryear are gone from google except yours

RRP

Sorry to have hijacked this interesting post. It deserves to see the light of day again!

blind99

I like that, especially for the DFMT.  I don't think I'd use it with the smokeware cap - it seems like it might not sit solidly and you'd get some leakage around the edges.  plus, the smokeware cap holds a fixed setting very well.

OTOH I pulled off my smokeware cap last night and ran with the DFMT.  I am still not completely sold on it.  sometimes it doesn't rotate easily.  and with three vents coming out sideways, you always get a face full of smoke. 

the important thing to know is the minimum possible temperature.  that is, blower in but not running, vent set, and fire at a stable state. your disc would make the vent settings easy, especially if you sandwiched it under the DFMT.

Jeepster47

@blind99 ... I've run with just the wooden disk, with felt around the bottom edge, and with a heavy weight on top of the disk to hold it down.  The cook posted above is with just the disk and felt.  The natural airflow seems to be gentle enough that leakage around the disk (especially with felt) doesn't seem to be a problem from cook to cook.

Either ugly Daisy or the Smokeware caps work well, you just have to adjust/tweak them each time.  With the wood cap, so far, I've been able to literally throw the cap on and walk away.

blind99

Adding the weight makes sense.  Sounds like a good setup.  Weren't you the inspiration for the smokeware snuffer?  Maybe you could make something similar, but with a hole in the middle.  It could even go inside, with the cap on but the vents wide open, so rain wouldn't be a problem.

Ragtop99

I don't have much issue using the DW with the FB200.  I set it closed a little more than I would have for a normal (unassisted) cook at that temp.  Since not all cooks use the same temp, I tweak the setting for each one.  

Seems like a good idea for consistency when doing a natural draft cook.