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Storage Tank Top and Bottom Bosses

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Tennman, Jul 26, 2013.

  1. Tennman

    Tennman Minister of Fire

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    Do you guys think it makes any difference if the boiler supply 1 1/2" boss is on the very top of the storage tank dome vs being down the side of the dome... say 1 o'clock. Just wondering about circulation with the top supply line entering at somewhat of an angle vs straight down vertically. It gut says its in the noise and doesn't make any difference, but if there is an advantage of the hot entering from the very top of the dome I'd like to know. On the bottom I'll have a small emergency drain, but plan on putting the 1 1/2" boiler return slightly up from the very bottom just to conserve height.

    Plan on having the demand supply/return bosses just below and above the dome to barrel welds (welded to the barrel section). Also adding a mid-tank cross feed line... just because I've seen it in the sketch and what the heck, can't hurt.

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  2. JP11

    JP11 Minister of Fire

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    My input and output from vertical stacked tanks is just prior to the start of the dome. Figured it was easier to have them weld on the flat steel instead of the dome. I guess I it didn't matter, they were pros. But that's what I did.
  3. JP11

    JP11 Minister of Fire

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    I didn't do any dedicated cross feed lines on my two vertical stacked 500s. I was shocked at how fast heat went from one tank to another. I was trying to charge just one. but didn't close one of the 1.25 lines. Heat was moving FAST between the two.

    JP
  4. Bob Rohr

    Bob Rohr Minister of Fire

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    I have seen of number of tanks built with a curved or bent dip tube installed in a side port to divert flow to the far reaches of the tank. It is easily done with a double taped bushing. You lessen the potential for thermosiphoning by using side ports and not the top of the dome. But that high point on the dome is an excellent location for a float style air vent.

    Here is a diverter tube I built for a tank.

    Up size the port you weld on to get good flow in the double tapped bushing.

    Attached Files:

    ewdudley likes this.
  5. Tennman

    Tennman Minister of Fire

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    Thanks JP and Bob, It didn't occur to me to mention that I'm stacking the tanks vertically beside each other, but it looks like you guys figured that out. So the tanks are ~118" long top to bottom. I have 121" floor to ceiling joists. So my tanks will be just like yours JP. Maximum height, minimum floor space.

    So JP, if I understand, the hot from the boiler and cold return to the boiler is below the dome to barrel weld? That's where I intend to put my hot supply to the house and the return from the house.

    Bob, My understanding was to insert the hottest water at the highest point to maximize... I guess the temp differential top to bottom. I have this impression from reading over the years about this guy Siggy having an very tall tank that was a good thing. I still intend to have an air vent at the top of the tanks but was planning on installing it in the black iron manifold connecting the top fittings. Thermosiphoning... I can see how your diverter would help. I understand the design and apparently it's not that critical to introduce the hot supply water at the very top of the tank. Tank is ~37" in diameter with makes the dome height ~18". Your diverter is maybe 6". Thanks for the help. Welding commences next week.
  6. Bob Rohr

    Bob Rohr Minister of Fire

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    I got the idea when I saw some of these Swiss tanks. They use that angled side port connection detail to eliminate any ghost flows, sort of like the heat trapper nipples installed on most water heaters that you purchase. The heat trapper nipple has a small rubber flapper to act as a check to prevent thermosiphon. I thought the side port idea was a better solution.

    Some wild tank ideas and video on this site including taking a tank up the mountain under a gondola.

    Attached Files:

  7. JP11

    JP11 Minister of Fire

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    Yes, you have it right. Not sure if you can find some of my old posts showing pics.

    There are 5 taps on each tank.. on the "barrel" portion as you call it. The part made with flat steel. Mine have 2 taps at the top of the barrel, and two taps at the bottom. I used 2" on those. I also added a 1" for probes. I used 1.5 inch copper to attach the boiler to storage. The lines were near identical lengths.. I did put T's and ball valves to be able to isolate and balance flows.

    I used 1.25 plumbing to go from tanks to storage.

    Bottom of the dome I put a fitting in for drain. Top of the dome I put a fitting in for a float type air vent.

    I gotta tell you.. You are gonna be CLOSE on ceiling height. I had to get the dome up BETWEEN the joists to stand up. I know I posted pics of how I stood em up. I had feet welded on.. The issue is you gotta get that bottom drain with a elbow on it. I think I had 10'4" to the bottom of my joists, and I almost gave up while doing it.
  8. ewdudley

    ewdudley Minister of Fire

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    If you go in at points on the barrel, all volume above the top port and all volume below the bottom port will be lost for heat storage purposes. Unless you use piping inside that tank to get the drawing/injection points up nearer the ends of the domes, as Bob Rohr shows above.
    mikefrommaine likes this.
  9. JP11

    JP11 Minister of Fire

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    I disagree. Now you might not pull the absolute hottest water in the tank that there is... but I'm pulling and pushing 25gpm out of those holes. The water does conduct the heat. It doesn't just go to the top of the dome and stay there, never to be seen again.

    JP
  10. Tennman

    Tennman Minister of Fire

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    EW, yes my boiler manifolds will be at the top and bottom. My situation is exactly the same as JPs.

    JP, I searched for pics of your tanks here but struck out. It sounds like I need to duplicate you're manifolds. Fortunately there's not a ceiling in my boiler barn so I think the tanks will rotate up between the joists... I hope. So if your boiler supply and return manifolds are between the floor and ceiling I'm guessing those ports on the domes can't be on the very top and bottom. I will have height for small drains and air vent ports, but not my 1 1/2" black iron manifolds. I think what I'm hearing is that its not a big deal if those top and bottom ports are not on the very top and bottom. Bottomline, sounds like yours work well and I'd like to copy them! You know what they say about imitation and flattery. Once I get the flow ports straight, I'll ask about sensor ports. Thanks all.
  11. ewdudley

    ewdudley Minister of Fire

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    Then just put two ports on opposites sides of the middle of the tank and let conduction and wishful thinking do the rest. Float some warm Guinness gently on some cold pilsner and judge for yourself.

    You can either go in at or near the ends of the domes, or you can go in the side and use a riser or dip tube to reach near the ends of the tank. The nearer the ends the better, but since the volume decreases so fast as you get closer there's no need to worry about the last couple inches.
  12. JP11

    JP11 Minister of Fire

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    Found some.

    http://www.hearth.com/talk/threads/two-tanks-in-and-upright.84893/#post-1091580


    http://www.hearth.com/talk/threads/...e-before-plumbers-show-up.85565/#post-1103225

    Dudley.. Those two liquids have different specific gravity, thus their "floating" Put cream in your coffee? Do you get "cold spots?" In my situation, I didn't feel it necessary to chase the dome. I seem to get the tanks 195 top to bottom, and it heats the house till the top gets to 135. Now, is there warmer than 135 water up in that dome when it kicks off. Likely yes. Is it enough for me to chase it. No.
  13. ewdudley

    ewdudley Minister of Fire

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    You're right, bad example because after all, hot and cold water have the same specific gravity.

    Believe what you like, my advice is directed at those who need to avoid the mistake of porting into the sides and expecting it to work.
  14. JP11

    JP11 Minister of Fire

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    You mean just like mine is set up? It's in the sides. Probably 8 feet separates the in and out ports. I just finished a burn.. so it really hasn't stratified much. But it's 196.2 on top and 193.3 on the bottom. Pump is still running as the boiler is still hot. I usually see 10 to 20 degrees between top and bottom. More if there's just small loads infrequently.

    JP
  15. Tennman

    Tennman Minister of Fire

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    Got it. I will be near the top and bottom but what I'm seeing is that not being at that very top and bottom is not that big a deal. I will be welding 4 angle legs instead of a base ring so I'll get closer to the bottom for the boiler return. Thanks all and JP for the pics. I'll post pics after I raise the tanks.
  16. ewdudley

    ewdudley Minister of Fire

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    Just do the math. For 500 gallon tanks typically 1/6 is lost on the top and 1/6 is lost on the bottom when the ports are at either end of the barrel, yielding a 333 gallon tank. 1000 gallon is not so bad since they are skinnier. Like I say, if you think conduction will do what you need, then just put one port in the middle and Bob's your uncle.
  17. Tennman

    Tennman Minister of Fire

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    EW, to clarify, I do intend to put my boiler ports as high and as low as I can on the domes. That's what I meant by near top and bottom. I just can't get them at the very ends of the domes due to lack of height. Thx
  18. If you go with a double tapped bushing and a diverter tube like Bob posted you get the best of both worlds -- it fits your space and you are taking advantage of the full capacity of the tanks and the hottest water at the top.

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