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anyone stacked 1000 gal propane tanks?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by cjdave, Nov 27, 2011.

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  1. goosegunner

    goosegunner Minister of Fire

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    How would you compare them, either one stand above the other for efficiency or ease of use?

    Do you have storage with the woodgun?

    gg

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  2. cjdave

    cjdave Member

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    should I worry about the feet of the tank sitting right on the concrete, like should I try to isolate the steel feet from the concrete say with a plywood shim to stop some heat transfer or am I just getting crazy now?
  3. Der Fuirmeister

    Der Fuirmeister Member

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    Both are very good. They operate differently, and have their own benefits. The Garn really needs it's own outdoor housing. We used a 20' long ISO shipping container. The Wood Gun is installed in the lower level of my home. Both have a vacuum induction fan vs. a fan that pressurizes the fire box. If either unit leaks they simply suck in air. I chose the Wood Gun for my home because I like the idea of making a fire in the morning without having to walk out in the snow and 4* temps (like it was here this am). I've watched my neighbor filling up his outdoor "smoking hut" in the cold wind. Doesn't look like fun. His is a non-gasification type and he burns almost twice the wood I do with a smaller home.

    Efficiency is about the same. There were variables in the tests, but I've read independent lab reports showing the Garn in the low to mid 90% range primarily depending on the water temperature in the tank. The Garn flue temps range from 300* to 350* at the stack (up to 400* inside at the gauge). The WG is almost too efficient. I'm careful to keep the flue temps above 230* minimum with normal temps running in the 270* range. I've never seen it go above 305*

    We use the Garn to burn scrap wood from shipping crates etc. The Garn handles nails with no problem. The WG does not handle nails. Cleaning the ash from the Garn is easier, just using a square shovel. The WG is a bit more tedious. I use a wood ash vacuum cleaner which helps. Being an open tank type testing the Garn is more critical. Both light very easily and in a similar fashion. Turn on the fan put the newspaper on top of the dry wood or kindling and light. I can run them both with the door open. I liked the manual timer Garn has on their controls so much that I installed one on the WG. That way it doesn't keep running when the fire goes out (and suck the heat up the flue). Burning the WG into storage greatly reduced the amount of creosote in the flue compared to the first year when it cycled on and off.

    The WG really should have a seamless SS pipe or pipe with the joints sealed with high temp tape etc. I have sectional black pipe now, but fabricated a flue pipe from Sch. 10 SS pipe. It will be installed during the next warm spell. The new flue pipe has flanged / gasketed doors on it at the bends to make inspection / cleaning a 10 minute job. No more worries about leaking pipes. We vent our Garn upwards (vs. down into a barrel as Garn recommends) with 15' of pipe just to reduce the smoke during lighting. After the first 5 min. it's just steam for the most part, but with the unit only 10' from the shop I'd rather not have any smoke at all. The shop roof and walls are steel so I'm not worried about sparks. I intend to make a spark arrestor / heat recovery barrel that will sit under the exhaust elbow and then vent upwards. The barrel will have an outer jacket for the intake air to run through and be preheated before entering the Garn. Next year's project....

    The Garn can be over fired, the WG just shuts down, but I try not to run the WG that hot. Right now I have 100 gals. of temporary storage on the WG plus a 215 gal DHW preheat tank, but I'm in the process of welding up a 750 gal. tank from 12 gauge 201SS sheet and 304SS angle. 201SS sheet is much cheaper than 304. I have a similar 215 gal. SS storage tank that I made for the DHW preheat tank. A pex HX is used to transfer heat to the DHW preheat tank. 300' of 1" pex runs through it from my well before going into my LP hot water heater. The preheat works so well that we no longer use LP.

    The Garn needs to have fire brick replaced every other year....cheap brick - $12, easy 10 min. job. The WG needs to have the center brick replaced every 7-8 cord, for me roughly every other year. Haven't done that yet, but it's due. The brick run $140 from AHS plus freight which was estimated at $50. So I decided to buy 50 lb of refractory cement and make my own. I suspect replacing those will take a few hours.

    The Wood Gun has had wear on the door gaskets. I'll be replacing those in a few weeks. I added an "L" shaped piece of sheet metal to the rear door where the hot gases and ash sand blast the door gasket. This seems to be working well. When I replace the gaskets I intend to add the sheet in the high wear areas. Hopefully this will extend the gasket life to 3-4 years.

    It was difficult getting information directly from Garn, but the rep I bought from in MN was very helpful. Wood Gun from AHS doesn't have reps in WI and information from them has been variable with the change of personnel they've had.

    Both are excellent units. Both made in the USA and I'd recommend either one, depending on your circumstances.....or if you're like me, both.
  4. Der Fuirmeister

    Der Fuirmeister Member

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    I can't imagine there's much heat transfer from the steel to concrete in that small surface area.....
  5. cjdave

    cjdave Member

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    Well with the way I build my feet I have full saddle contact with the tank 30" long and the foot is 6" wide, so that gives me 5 square feet of surface contact with the floor. 5 Sq ft is quite a bit of contact and I know how good concrete is at sucking the heat out of anything warmer than it.
  6. Don't know if you need it, but it seems like cheap insurance to put wood under the feet. I would consider using pressure treated.
  7. goosegunner

    goosegunner Minister of Fire

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    I put 6 layers of pressure treated wood under my tank's feet. It was advised here that the loss would be very minimal through that much wood.

    I then added 8" of polyiso foam board under the tank covering the concrete. It was a pain to cut the pieces but I got it for free.

    gg
  8. cjdave

    cjdave Member

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    unfortunately I only have about 3.5" above my tanks to the ceiling, that means what ever i put under the tank feet needs to be 1/2" or at most 3/4". I guess there is a chart somewhere that gives r values for plywood?..... yep found it 1/2" plywood is R-.63 and the standard rating is plywood is R-1.25 per inch. so 3/4 ply would give me about R.9. dose not sound like much but i guess its better than nothing...
  9. Der Fuirmeister

    Der Fuirmeister Member

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    You could if you are concerned. The Garn has a continuous foot running the length which is about 9 inches wide and welded the entire length. Garn recommends setting the boiler on (2" R10 I believe) foam board, but with that much footing area (~14.25 sq. ft.) the foam can handle the weight (~15,000lb). It ends up at 7.3 psi. Standard Dow foam is rated at 15 psi and they usually have the stronger 25 psi foam available at lumber yards. You can get up to 100 psi foam as well..... http://building.dow.com/na/en/products/insulation/rigidfoam.htm

    Do you know the weight of your tank? If you have 5 sq ft. (720 sq. inches) and get the 25 psi foam it could handle up to 18,000 lb. I would recommend looking into it if you're concerned. Is the concrete in your basement with all the parasitic heat loss going into your house anyway? My Wood Gun is in my basement and only has the 1" insulation which it came with. The basement stays a comfortable 68 degrees all winter.
  10. Der Fuirmeister

    Der Fuirmeister Member

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    I'd much rather have another inch above the whole tank than an inch below just 5 sq. ft. of it. Do the heat loss calcs on the loss at highest tank temps at the top over the whole area vs. the lowest temps on the bottom and just 5 sq. ft.
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