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Storage "without storage"

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by jebatty, May 2, 2008.

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  1. jebatty

    jebatty Minister of Fire

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    Storage and its cost is a stumbling block for many who have/want gasifiers and are concerned about efficient operation. Is the following a workable idea that may help ease this question:

    The idea is based on the Tarm but I assume it is usable with any gasifier. Typical boiler plumbing is boiler supply to Termovar/mixing valve to load and to boiler return. Insert a (used) hot water heater tank between the boiler supply and the Termovar/mixing valve. This would have the effect of increasing the boiler system capacity, so with the Tarm, for example, boiler system is about 50 gallons, plus a 40-80 gallon electric hot water tank = 90-130 gallons of boiler system water. This would result in a longer burn to bring system up to temp and to return to temp after cycling, and should increase efficiency accordingly.

    Advantages: reduction in plumbing costs, valves, etc. associated with traditional storage; increased simplicity in system.

    Disadvantages: longer time to come up to temp from a cold start; need larger expansion tank; need to obtain a (used) hot water heater.

    What do you think?

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  2. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    I had PLANNED to go with a 160gal twin coil tank (more of a buffer tank than storage tank) which would allow input from either wood or solar on the bottom. The top coil would be out to the oil boiler. I had hoped to set it up so that, when the tank temp was down, it would automatically switch to heating the oil boiler (through the existing 20-plate HX), then return to heating the tank when demand subsided.

    The state of the economy has told me to NOT spend 2G on the tank (exclusive of shipping, controls, installation) right now.

    Thank goodness the NY Director of Budget told us that NY will be out of the recession late this year. Where do we get such intelligent people? For the longest time none of that type (politicians) wanted to even be caught dead saying the R-word, now they actually know when we are coming out of it. As if it's like flipping a switch. Well then, flip the switch now instead of later, tyvm!

    Of course, what the DoB failed to mention was that, the reason we were going to leave recession was that we were going to go into depression.

    Fools!!

    Sorry I didn't answer your question
  3. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    That's a buffer tank.

    To be a storage tank, it needs to be able to absorb the heat output of the boiler during a burn. In other words, if you had no zones calling and loaded the boiler normally, the tank would have to be large enough to absorb the entire output of the boiler, without the boiler ever hitting high limit and going into idle.

    Adding a buffer tank could certainly lengthen the cycles if you put the right pumps and controls on it, but it can't replace a storage tank, for what a storage tank does.

    Joe
  4. Jim Post

    Jim Post Member

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    I like the concept, especially since I have an extra hot water tank that was to become a solar batch heater...I'll be interested to hear the experts chime in on the pros and cons of this approach. It's like a garn system on a extreme reduction diet...It seems to me increasing the amount of hot water on the boiler side of the system would allow for longer 'off' cycles.
  5. jebatty

    jebatty Minister of Fire

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    I agree it's a buffer tank, but as such it does store heat to give back to the zone(s) of a greater volume than just the boiler itself, thus allowing for longer times between cycles.

    Cost-wise it may be a quick way to go with advantages outweighing disadvantages pending adding significant storage later.
  6. nmerrill

    nmerrill New Member

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    You also need to consider the in/out piping arraignment the tank has - I assume your boiler supply and returns are larger than 3/4 in? I think in some cases you can use the heater element holes in electric water heaters though.
    Nat
  7. solarguy

    solarguy New Member

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    If cost or space for storage is an issue, you could try installing a 4 way modulating mixing valve & let it run your system water temperature based upon outside air temperatures. We did this for a customer that bought an Eko 40 from us & he's gotten up to a 14 hour burn. It doesn't address the flat out burn issue when using storage but a 14 hour burn is pretty impressive.
  8. SteveJ

    SteveJ Member

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    Solarguy,

    Can you post a piping diagram?

    Thanks,
    Steve
  9. solarguy

    solarguy New Member

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    Don't know how to post a diagram...
  10. SteveJ

    SteveJ Member

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    Solarguy,

    Is there a piping diagram available in any electronic format?

    If not, can you scan one into a pdf or something?

    If so, can you PM the diagram to me?

    Thanks,
    Steve
  11. solarguy

    solarguy New Member

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    Steve,

    If you have an autocad program I can burn something up & email it to you.
    If not there's always the old fashion way, fax number??

    Bob
  12. SteveJ

    SteveJ Member

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    Bob,

    Autocad - can you export to a dxf format?

    If not, an autocad file would be great!!

    email sjanzou@gmail.com


    Thanks,
    Steve
  13. solarguy

    solarguy New Member

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  14. Jim Post

    Jim Post Member

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    Could you explain alittle more about this set up....What type of radiation is being used? What water temps are they seeing in the shoulder seasons? How does a 4 way mixing valve work with outdoor reset? How much does it cost? Is another control device necessary? Thanks.

    jp
  15. solarguy

    solarguy New Member

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    I just put the link out there so folks would get the idea.
    The taco valve has the outdoor reset built right in.

    The eko 40 is hooked up to a warm air system, 105 in the shoulder months, 130 when it's cold
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