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storage tank with closed system

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by mikeyny, Dec 2, 2007.

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  1. mikeyny

    mikeyny Feeling the Heat

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    upstate ny
    Is there any other reason not to set up a storage tank directly to the wood boiler in a closed system other than needing a large expansion tank? There would definitely be less loss of efficiency in the system and it seems to me it would be a lot less complicated than using multiple heat exchangers. I presently use a 110 gal. tank as a dump zone in case of overheating on warm days. My wood boiler is a bit small for my big old house so it rarely overheats. I would like to build a larger tank for storage and maybe connect directly to the boiler. Any thoughts?

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  2. leaddog

    leaddog Minister of Fire

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    The only problem is when you increase the volume of water you reduce the recovery time of raising the water temp. This isn't a problem most of the time as you keep the temp up but if you don't fire the boiler for a while then it take longer to get up to temp. This can be compensated by having a bypass (either manual or auto) to bypass the tank or slowly feed it while you are useing the heat else where. You will still need hx to get the heat for other uses such a dhw, hottubs, etc.
    There are some advantages such as water quality, no evapoation loss, ease of insulation.
    Also make sure you have a relief valve ANY place on the system that you might isolate. And don't skrimp on the valves. If you have a problem you don't want to drain the whole system
    leaddog
  3. Eric Johnson

    Eric Johnson Mod Emeritus

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    I've learned a lot over the past few days about pressurized storage. I really didn't realize how much extra expansion capacity you need with something like 1,000 gallons of pressurized storage. As Joe Brown described it in another thread, it takes some engineering and some expense. Not like you can just hang another Extrol 60 on there somewhere and get by. He suggests an 80-gallon hot water tank and some fancy piping and instrumentation.

    Hot water storage seems to be one of those things where there are many different ways to do it, but they all involve compromises.
  4. verne

    verne Member

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    I spoke with zennon and dave and both thought I only needed 40 gal of storage with 1000 gal tank . Also with a direct hookup you only need one mixing valve between top and bot of boiler and tank .which you want anyway top control return temp . I was told to use termavar or laddomat with preferance.the price for added expansion about $200. Not bad even if you have to buy new tank for $1200 [vessel only] plus as Im finding out ,If you buy new they deliver . not an easy task of getting a used 1500 lb tank out of someones yard and on a trailer etc.I currently have an offer of two free tanks , but I have to figure out how much it will cost me to get it home.
  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    Maybe you can rent a Ryder truck with a lift gate. I'm not sure if the gate would be big enough to handle the tank. I'm sure the gates are rated for at least a ton, probably 5,000 pounds. If the tank is less than eight feet long, it would work pretty well, I think.
  6. verne

    verne Member

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    highland ny
    .I dont know ? the 1000 gal is 16' 500gal is 10'
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