Welcome!


This is a membership forum. As a guest, you can click around a bit. View 5 pages for free. If you would like to participate, please join.

[ Pitmaster Club Information | Join Now | Login | Contact Us ]

There are 4 page views remaining.

Announcement

Collapse
No announcement yet.

Lower Vent Shutter for the PBC

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Lower Vent Shutter for the PBC


    Click image for larger version

Name:	PBC Vent Mod.jpg
Views:	177
Size:	63.7 KB
ID:	61097
    There have been a number of posts regarding adjusting the lower vent opening on the PBC. I decided to toss the supplied circular cover and use one with a straight edge, basically a piece of thin aluminum sheet about 4" wide by 5" high. Now, how to place it to get the "right" area? The vent hole is 3" in diameter, so it has an area of 7.07 sq in. So the sea-level setting of "1/4 open" translates to 0.88 sq in, and "1/2 open", to 3.53 sq in. A little searching on the internet will yield formulas for the area of a Circular Segment as a function of its height. The height is the distance from the circle's circumference to the straight line cutting across the circle. (Now, aren't you glad you stayed awake in geometry?) Here's an abbreviated table; the first column is the fraction of the full open area, the second column is the segment height IN MILLIMETERS.

    Open Height
    1/8 5.5 mm
    1/4 9 mm
    3/8 12 mm
    1/2 15 mm
    3/4 24 mm

    At 9mm, opening or closing the shutter 1 mm changes the % of full opening by about 4%, so it's pretty fine control. It's not a linear relationship because, well, a circle is not linear. If you want a full table, email me.

    To make the vent shutter, get a piece of thin Al; Home Depot has 1 foot squares 0.020 thick. Cut a piece with strong scissors to about 4" wide and about 5" tall. Gently roll it to fit the curve of the barrel. I made some guide rails for mine as shown in the picture, but you can just use a magnet (also at HD) to hold it in place. Measure up from the bottom of the vent hole to your desired set point (9mm for 1/4 open), and file a notch in the edge of the vent hole as reference. I marked a mm scale on my guides.

    Now you can reproducibly set and adjust the vent opening. The bonus is, you can easily close it completely after the cook, plug the hanging bar holes with wine corks, and save the charcoal for next time. If you need help emptying 4 wine bottles, let me know.
    Attached Files

    #2
    Thanks for the info!

    Comment


      #3
      Nice post Doc H. How has this worked for temperature control? How does the temp profile differ from a standard PBC? What temps can you cook at with your mod?

      Comment


      • Doc Hazard
        Doc Hazard commented
        Editing a comment
        It shouldn't be any different from the standard PBC, given the same opening area. The comments I've read seem to say that the temperature is not a strong function of the lower vent size. That's generally been my experience as well. It has an effect, but modifying the upper, exhaust vent area is much more effective. I guess that makes sense, since for a fixed and relatively small exhaust, as in the PBC, it doesn't matter much how big the possible input is: no matter the size no more air is going to go in than can get out. Now, if you cracked open the top, or took it off, to get searing temps, then the results would be much more sensitive to the input area. I like the shutter primarily because I know what the setting is and I can reproduce it. And mostly, because I can easily close it completely to snuff out the fire after a short cook.

      #4
      Looks good, been planning something similar myself once the current version wears off

      Comment


        #5
        So you rolled it to conform to the barrel shape. But the original is not rolled correct? Mine is flat and does not hug/conform to the barrel.

        Comment


        • Doc Hazard
          Doc Hazard commented
          Editing a comment
          I threw away the original round vent cover. The shutter is made from very thin Al sheet (0.020 inches). I'm sure you could use a couple thicknesses of heavy Al foil. "Roll" is too strong a word: I kind of bent the sheet to match the curvature of the barrel, and of course, my rails force it to match. But you can just use a magnet to hold the sheet of foil. The real info here, such as it is, is the area vs. segment height. ---Doc.

        #6
        IMO the lower vent design on the PBC seems like an afterthought. It's not cut to fit (can't completely close), every few cooks the nut inside seems to come loose during a cook and I end up propping it open with a little wire or nail or whatever is around.

        Comment


          #7
          That is neat. I'd like to have 4 very small vents, whatever would equal the 1/4 gap. See how that would roll with 4-6 briskets hanging in that sucker.

          I'm with Whitey for now. My lower is set for everything. I manipulate upper vents for temp control, if necessary.
          Last edited by Jerod Broussard; February 10, 2015, 04:41 PM. Reason: I does not equal I'd

          Comment


          • Doc Hazard
            Doc Hazard commented
            Editing a comment
            Well, 4 holes each 0.53 inches diameter would give you the 0.88 sq in opening of a 1/4 open vent. Given the mods you've done, this should be easy for you. How about a similar shutter in the top, or near the top of the barrel? ---Doc.

        Announcement

        Collapse
        No announcement yet.
        Working...
        X
        false
        0
        Guest
        500
        ["pitmaster-my-membership","login","join-pitmaster","lostpw","reset-password","special-offers","help","nojs","meat-ups","gifts","authaau-alpha","ebooklogin-start","alpha","start"]
        false
        false
        {"count":0,"link":"/forum/announcements/","debug":""}
        Yes
        Rubs Promo

        Spotlight

        These are not ads or paid placements. These are some of our favorite tools and toys.

        These are products we have tested, won our top awards, and are highly recommend. Click here to read how we test, about our medals, and what they mean.

        Use Our Links To Help Keep Us Alive

        A big part of this site is our unbiased equipment and product reviews. We love playing with toys and we have no problem calling them the way we see them. Some companies pay a finder’s fee if a reader clicks a link on AmazingRibs.com and buys a product. It has zero impact on our reviews, zero impact on the price you pay, and the sites never tell us what you bought, but it has a major impact on our ability to keep this site alive! So before you buy, please click our links. Here’s a link that takes you to a page on Amazon that has some of our favorite tools and toys: https://tinyurl.com/amazingribs


        Our Favorite Backyard Smoker

        The amazing Karubecue is the most innovative smoker in the world. The quality of meat from this machine is astonishing. At its crux is a patented firebox that burns logs above the cooking chamber and sucks heat and extremely clean blue smoke into the thermostat controlled oven. It is our favorite smoker, period.
        Click here for our review of this superb smoker


        Bring The Heat With Broil King Signet’s Dual Tube Burners

        3 burner gas grill

        The Broil King Signet 320 is a modestly priced, 3-burner gas grill that packs a lot of value and power under the hood. Broil King’s proprietary, dual-tube burners get hot fast and are able to achieve high, searing temps that rival most comparatively priced gas grills. The quality cast aluminum housing carries a Limited Lifetime Warranty.

        Click here to read ourácompleteáreview


        The Pit Barrel Cooker May Be Too Easy


        The PBC has a rabid cult following for good reason. It is absolutely positively without a doubt the best bargain on a smoker in the world. Period. This baby will cook circles around the cheap offset sideways barrel smokers because temperature control is so much easier.

        Click here to read our detailed review and the raves from people who own them


        Fireboard: The Ultimate Top Of The Line BBQ Thermometer

        Fireboard Labs Product Photo Shoot. Kansas City Commercial Portrait and Wedding Photographers ©Kevin Ashley Photography

        With the ability to monitor up to six temperatures simultaneously with either Bluetooth or Wifi on your mobile phone, tablet, or computer, Fireboard is the best digital thermometer we’ve tested.
        Click here to read our detailedáreview


        The Good-One Is A Superb Grill And A Superb Smoker All In One


        The Good-One Open Range is dramatically different from a traditional offset smoker. By placing the heat source behind and under the smokebox instead of off to the side, Open Range produces even temperature from left to right, something almost impossible to achieve with a standard barrel shaped offset.

        Click here to read ourácomplete review

         

        Comprehensive Temperature Magnet With 80+ Important Temps

        Amazingribs.com temperature magnet
        Winner of the National BBQ Association’s product of the year award. This 8.5″ x 11″ magnet contains more that 80 benchmark temperatures for meats (both USDA recommended temps as well as the temps chefs recommend), fats and oils, sugars, sous vide, eggs, collagens, wood combustion, breads, and more. Although it is not certified as all-weather, we have tested it outdoors in Chicago weather and it has not delaminated in three years, but there is minor fading.

        Click here to order.


        Is This Superb Charcoal Grill A Kamado Killer?


        The PK-360, with 360 square inches of cooking space, this rust free, cast aluminum charcoal grill is durable and easy to use. Four-way venting means it’s easy to set up for two zone cooking with more control than single vent Kamado grills. It is beautifully designed, completely portable, and much easier to set up for 2-zone cooking than any round kamado.

        Click here to read our detailed review of the PK 360

        Click here to order directly and get an exclusive AmazingRibs.com deal