Heat Storage Tank

Discussion in 'Alternative Energy' started by Jackpine Savage, Aug 7, 2006.

  1. Jackpine Savage

    Jackpine Savage Well-Known Member

    Jul 3, 2002
    Central MN
    Has anyone built an indoor water heat storage tank? I'm planning the installation of a Tarm wood boiler. Tarm has an 822 gallon insulated tank for about $1900. Besides being expensive, it's round and would take up quite a bit of space in the basement.

    I'm thinking of building my own tank using plywood, angle iron for exterior bracing, foam insulation, and a EPDM liner. It needs to be about 4'x4'x8'. The Tarm tank uses High Temp extruded urethane rated at r-14. I'm just starting to do the research on what type of foam to use and where to find the EPDM liners. If anyone has done this and/or has information available to share it would be most appreciated.
  2. WisJim

    WisJim Well-Known Member Supporter

    Jan 13, 2004
    We used to build basement heat storage tanks with wood framed walls and swimming pool liners, insulated with foam and/or fiberglass. It has been a long time (late 1970s-early 1980s) and I no longer live close to where we did them, so I haven't seen any of the systems in 15 years, but they did okay the first 10+ years.

  3. SolarGary

    SolarGary Well-Known Member

    Sep 7, 2005
    Is the tank 4X8 and 4 ft high, or 4X4 and 8 ft high?
    An 8 ft high tank would have 3.5 psi at the bottom, which adds up. That is, there would be a lot of outward pressure on the sides of the tank near the bottom.

    The EPDM is available in our local Home Depot, and the local green house in 12 ft wide. You can also get it on the internet. This is one place:
    EPDM is rated up to about 180F.

    One insulation choice would be the polyisocyanurate rigid foam boards. Some lumber yards sell it -- it is usually light brown in color, and usually has an alum foil face sheet. It has a good temperature capability -- its used by some solar collector manufacturers as insulation behind the absorber plate. It will absorb water if in a wet/moist environment, so you would need to keep it dry. It has a high R value per inch (6 I think).
    The extruded polystyrene (XPS) that lumber yards sell (pink or blue) is only good to about 130 F.

    You would need to be careful in the design to make sure that the stiffeners for the sides have enough bending strength (depth) to prevent bowing out. If one wall of the tank is 8 ft long, I would see if you can do a tension tie across the tank at the 4 ft point, so that you break the 8 ft span into two 4 ft spans.

  4. MELOC

    MELOC Master Of My Domain

    Sep 26, 2005
    i read somewhere that someone had a 1000 gallon tank in their basement and allowed it to shed heat as a heat source in the winter. they stated they would go away for several days and not heat the water and the tank helped to heat the house from the basement up. is it really necessary to insulate the tank? perhaps you could just use the non-insulated tank in the winter.

    i thought about trying this with an old 300 gallon oil tank and a coil of copper around the wood furnace stove pipe. i could even use that source for homebrew space heating with old automobile radiators or heater cores and dc powered fans and a small battery bank and solar charger.
  5. ET1 SS

    ET1 SS zone 5 - riverfrontage Supporter

    Oct 22, 2005
    Forests of maine
    We have a source of 55 gallon barrels [ FREE ] and I have four of them so far cleaned up and ready to go.

    As soon as most of the other stuff is in place, these four barrels will be our heat-storage bank.