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Pictures Black Bear and Wood Tank Fram

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Grover59, Dec 10, 2007.

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  1. Grover59

    Grover59 Member

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    I will try my hand at posting some pictures they are not that good but you can see my messy basement. Does anyone think this tank frame will hold water?

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  2. Nofossil

    Nofossil Moderator Emeritus

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    I'd wrap aircraft cable around the tank, spacing it out more in the center of each side to approximate a circle, then tighten the snot out of it with turnbuckles. I assume plywood and EPDM on the inside?

    I haven't seen pictures of 'known good' wooden tank designs. Any out there?
  3. Grover59

    Grover59 Member

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    Yes you are absolutely right water likes round and will seek its own level, I have done a lot of research and have found that this type of tank is very common. I did it this way because of cost and it will fit where I need it. I have a lot of screws and lag bolts in it and I was told to put the 2x8 on end all around it for added support, much like when building forms for cement. I have seen plans for another tank built with wood my design is big time over kill compared those plans, and that tank had an 2 8 foot long walls.
  4. Grover59

    Grover59 Member

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    Yes it will be 3/4" plywood and EPDM liner.
  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    The tank looks good to me, but I'm not an engineer like some of these guys. I'm more interested in those blue flames in the bottom chamber of that BBB. What point are you at in the cycle?
  6. Grover59

    Grover59 Member

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    When I took the picture the blower had just started about 10 minutes before, the wood in there now has been there for awhile so all of the quick burn stuff is gone and I see the blue flame. When I first stoke this up I will get a big orange blue flame for awhile untill all of the easy stuff is burned.

    Steve
  7. Nofossil

    Nofossil Moderator Emeritus

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    I'll play engineer for a minute. If I remember correctly, water pressure is about 1/2psi per foot of depth. At 4 feet, that's 2 psi, or about 300 pounds per square foot pushing outwards on your plywood. That's why I suggest the aircraft cable, and I won't swear that's enough. If your sides are 4 feet high and 6 feet long, that's about 3500 pounds trying to push each side panel outwards. Think about the possibility and consequences of catastrophic failure, and plan accordingly.

    I started out with a plan along these lines, and I finally opted for an external stainless tank that I got from a junkyard. The tank was cheaper, but I had to build an enclosure for it.
  8. Grover59

    Grover59 Member

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    Yes you are right that is about what the pressure would be, I belive it would be even more at the bottom of the tank. If I have to I could support the bottom and the top again with steel I have room to still get around the tank. Now the back walls of the tank are against the foundation walls so I may be ok there, I am more concerned about the other walls.

    Steve
  9. Nofossil

    Nofossil Moderator Emeritus

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    I see the 2x8 braces that you have on edge. The real need is near the bottom much more than at the middle.

    As someone mentioned earlier, water likes to be round. That's why virtually all above-ground pools are round. Any other shape requires much bracing. Since what you're doing is essentially an above-ground pool, perhaps you could get an idea of the amount of bracing required by looking at a rectangular above-ground pool. I think a company named Gibraltar makes them. The deck is part of the structure that's required to keep the sides straight. Steal shamelessly from their design.

    Can you tie the bottom plates together across the bottom of the tank? That would be absolutely critical. I'm thinking urethane glue, gussets, plywood, oak, steel, and anything else that can help ensure that the bottom edges can't flex outwards.
  10. Eric Johnson

    Eric Johnson Mod Emeritus

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    I don't know. I have a square concrete tank that has yet to see any water, so I'm just guessing, hoping and praying--all without the benefit of any engineering background or religious affiliation. However, my tank is a modified 2,500-gallon reinforced concrete cistern in my basement that I know held 2,500 gallons of water in the past. And when I say "reinforced concrete," I'm talking about old scrap iron, steel pipe and wood scraps, not a pattern of rebar. I know this because somebody knocked part of the wall out to get access to the space, so I can see what it's made of. I just blocked off one end with a cinderblock wall. So I've got a proven 6-inch poured concrete walls on 3 sides (independent of the foundation, by the way), and an insulated cinderblock wall faced with surface bonding cement making up the fourth side. I also plan to jack up the floor slightly and basically put the weight of the house on the new section of wall. I also have the option of bracing the wall against the foundation, which is about 6 feet away, but only if I see cracks starting to develop in the surface bonding cement once she starts to fill with water. The inside is lined with 2 inches of foam and lined with an EPDM pond liner. Here's a random pic, for what it's worth.

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  11. Grover59

    Grover59 Member

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    I could add another set of 2X8's at the bottom to stiffin that up, the bottom is bolted and screwed to 2 sheets of plywood that are screwed together with many screws.
  12. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    I said it last year. First person I ever heard of that is intentionally putting a thousand gallons of water in his basement. Seen it in a basement once, but it wasn't on purpose.
  13. Grover59

    Grover59 Member

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    I take your advece and put another set of 2X8's on the bottom, I knew this is where most of the load will be but thought in the middle was fine. So to be safe I wll add them, I will probably have to slde what have there now down and then add another set in the middle.

    Thanks,STeve
  14. verne

    verne Member

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    just as you said , concrete form , build it like one . pressure comes from height . so the shorter the side walls the better. typically ,the whallers are spaced twice as close at the bottom. also lace the corners and leave them long enough to add 2 vertical strongbacks at each corner.
  15. Grover59

    Grover59 Member

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    I am going to get that done tonight when I get home, how close to the bottom do you think the whallers should go?

    Steve
  16. verne

    verne Member

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    i would start at 12" or under . The verticalls at the corners are nailed double to each whaler both sides to stop the laceing or corners from opening. nails are stronger for shear strength also if you can tap -con the bottom plates to concreat slab
  17. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Guys, it's a lot of weight, but it's not that much. 0.433 psi per foot of depth. Under two tons on a 4x8 sheet of plywood.

    My garage is an old barn with wood plank floors (over a full basement). This is old wood, not in the greatest condition (due to moisture from dirt floor in said basement), and the last owner had a Suburban, with it's entire weight split up on a few square inches under the tires.

    This looks like a workable design: http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Tank.htm

    The recommendations of some cross-bracing are pretty good. I'm thinking of building that sort of tank, and using threaded rod. That way, I can fit the cover, then tighten the rods to "squeeze" the cover a bit, making a better seal.

    Joe
  18. Nofossil

    Nofossil Moderator Emeritus

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    I'm not worried about the floor at all. That same force is pressing outwards on the sides - none at the top, but 250 pounds per square foot sideways at the bottom. I'm imagining the tank suspended sideways, with a car parked on the inside of a side panel. That's the force I'm worried about. In particular, bowing out the sides or pulling the corners apart. Usually, we design wood structures to be loaded in compression. This is loaded in tension. I'm too lazy to do the hoop stress calculations, and I don't want to give advice without some confidence that the results are safe and satisfactory.

    I'm hoping someone has a time-tested example.
  19. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Sorry I didn't specify - the number I gave was for the sides. The pressure downward is 1.732 psi - four tons on a 4x8 sheet of plywood.

    That sideways car analogy is good. Think of a floor. Make a 4x8 floor, and park a car on it. What size framing do you need?

    The 250psf number exists at the very bottom, but diminishes rapidly as you climb the wall, to zero at the top.

    The real loading is going to be the tension that the floor is under, as the bottom tries to spread. I think that decent plywood should take a lot of tension loading. I'd probably use 4x4's for the bottom frame, just so the plywood sides aren't sitting against the narrow edge of a 2x4.

    Joe
  20. Nofossil

    Nofossil Moderator Emeritus

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    We're all on the same page. I want to see pictures when it's full of water.
  21. Eric Johnson

    Eric Johnson Mod Emeritus

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    The basement or the tank?
  22. Nofossil

    Nofossil Moderator Emeritus

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    C'mon - I was trying to be nice!

    Sometimes, we learn as much from failures as successes. I do try and share the things I've done that didn't work, even when they're pretty boneheaded in retrospect.
  23. Eric Johnson

    Eric Johnson Mod Emeritus

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    For the record, I was referring to my tank and my basement, not Maine's. Looks to me like he's getting some good advice and appears to know what he's doing.
  24. Grover59

    Grover59 Member

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    I have purchased the 2X8 for the second set of whallers on the bottom, the plywood bottom of this tank is 2 sheets of 3/4 " plywood laminated together. Then there is 2 2x4's laying flat and screwed together, they also overlap at the corners. At the corners everything is overlapped and screwed and lag bolted together. I do beleive that the extra whallers on the bottom is a good idea for the cost it is a no brainer. I have talked to a couple of talk show guys up here in Maine, Prof. Dick Hill and Tom Gosie not sure if I spelled that right, they eat drink and poop this stuff and have built many of these wooden tanks. They basically said the same thing, water wants to be round, and they suggested the whaller to help this problem. Here is a link to a tank that was constructed it is only 3 feet high and this makes a difference for sure, but I tried to build mine much stronger then this one.

    http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Tank.htm

    STeve
  25. SteveJ

    SteveJ Member

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    Steve,

    I, too, am doing the rectangular 4x8 storage tank based on the link you referenced.

    I have 2 layers of framing with corners reinforced with the simpson steel Ls as shown in the picture.

    On the bottom and top I bolted two steel straps side to side 3' from either end.

    I just used a weak sheathing bottom but am using 3/4" plywood at the sided and end.

    The tank will set on a concrete floor so I am not too concerned with the bottom.

    I have the steel corners at the bottom, middle and top (yet to be completed).

    EPDM 0.45mil liner with 2" foam board between the liner and the 3/4" plywood.

    Hope it holds - let me know when you fill and I will do the same,
    Steve

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