FB Vent to Grate Height

[FredyzBBQ]

I'm trying to determine if this firebox door vent height
and fire grate height from floor is a good enough
setup to work. This is the second one, the first one I
had to come back and raise the fire grate as it was only
an inch off the floor of the firebox.

I see offsets and reverse flows with firebox vents on sides
and on doors or one or the other. The side is not an option
for me on this build.

The two red hashed holes for the vent (with the butterfly
behind) are more than big enough according to the pit calculator.

CC 18"W x18"H x38"L Octagon

FB 18"W x18"H x18"L Octagon

1 1/2" firebox floor to bottom of first air vent.

2 13/16" floor to fire surface of fire grate.

5 1/2" floor to center of butterfly vent.

14 3/16" Bottom of firebox to top of door without flanges

The green is the fire grate material and is supported by angle
iron that will go up the side and build a short grated box for the fire.

[Dirtytires]

I always like my vents lower...why not rotate your butterfly so the holes are left/right instead of top/bottom?

[FredyzBBQ]

Give me a few days to draw that in Vizio (the only reason I have a Microsoft VM). I've found if I can draw it everything comes out better. I never made mechanical drawings with it before the first grill. Takes the guess work out and parts magically fit. Maybe there is another easier and better drawing app for Linux I haven't found (in another thread).

Thanks for the idea! I'll update with the results.

[Kcd2016]

Sketchup can be run in your browser. It's easy to learn and pretty intuitive.

Librecad is simple 2d cad that's pretty easy that runs in linux. It works but I don't think it's under development anymore.

You could check out freecad but it's relatively complicated.

[FredyzBBQ]

Sketchup can be run in your browser. It's easy to learn and pretty intuitive.

Librecad is simple 2d cad that's pretty easy that runs in linux. It works but I don't think it's under development anymore.

You could check out freecad but it's relatively complicated.

Thanks for the ideas. Actually I've tried all 3. Sketchup is $120 yearly... the other two, same thoughts. Not supported and too complicated. guess I'll stay with what I got for now. I got a license of Visio 2013 while taking some classes and it's so easy for me to use... problem is I switched my computer to Linux to keep from paying subscription fees to MS anymore. I'm on a FOSS mission you might say. Free Open Source Software... Maybe I'll try and tackle free cad soon.

[FredyzBBQ]

I always like my vents lower...why not rotate your butterfly so the holes are left/right instead of top/bottom?

Ok, back to the grind, literally! I tried what you said, a 90 degree rotation to horizontal. However that didn't work out as good as we thought. both openings were at grate level and not a bit below.
So I tried lowering the whole butterfly assembly vertically, and at 45 degrees and 30 degrees.

One factor affecting things is included in this new drawing. It's something I call my rolling coal catcher to catch fire and coals accidentally rolling out the floor of the fire box when the door is open. It extends up from the floor at the opening of the FB 1". I was a scout "be prepared" was the motto. Hell now it might be .... who knows I'm afraid to ask.

So with that said, I drew it at the 30 degree angle shown here, plus I lowered it the most I could and still have a coal catcher lip at the door.

So with this setup I'd grind the coal catcher to leave an un-impeded opening for the lower port. The upper port will be lower than if at the vertical minimum height position too.
This setup will leave the bottom of the lowest portion of the intake 11/16" from the floor of the fire box and the fire grate surface 2 13/16" for a 2 1/8" air flow space from intake lowest point to grate surface.

This will also require I put the moving part of the butterfly on the outside of the door, which has pros and cons. I do like the pros though. easy cleaning, less dirt and debris to foul it.

What do you think? Is the hole low enough and the grate high enough?

[Dirtytires]

It definitely gets a little more air under the fire basket.

As far as ash and coals go, a fire basket does a pretty good job of keeping anything from rolling around and the pieces that falls thru can be stopped by a small lip on the firebox floor. In many cases, an ash pan does this job nicely.

[Brewmaster]

Looks like you're building a really nice beast! Personally, I'm a fan of this style round vent.....

[Brewmaster]

I should have mentioned that's not mine! Pic of my own attached below, it works great also.

[FredyzBBQ]

It definitely gets a little more air under the fire basket.

As far as ash and coals go, a fire basket does a pretty good job of keeping anything from rolling around and the pieces that falls thru can be stopped by a small lip on the firebox floor. In many cases, an ash pan does this job nicely.

Good thoughts, you have me thinking. Thanks appreciate it!

[FredyzBBQ]

Looks like you're building a really nice beast! Personally, I'm a fan of this style round vent.....

firebox vent 1.jpg

That's a pretty door too. I like both of them. Decisions decisions.... Thanks for the input and photos. I'd be interested in seeing more if you have them. Appreciate it!

[Kcd2016]

Thanks for the ideas. Actually I've tried all 3. Sketchup is $120 yearly...

no, there's a free version. Im using it. not open source though.

[FredyzBBQ]

Cool, I'll have to check it out again. Free versions of software are not always easily visible as the pay versions .

I hope it will do calculations, that's one thing I've gotten spoiled on, clicking on a shape I draw and then in the view menu, viewing the square inches of area it takes up. Makes calculations so easy.