Storage wont reach setpoint

ejhills Posted By ejhills, Jan 9, 2019 at 11:00 PM

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  1. ejhills

    ejhills
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    Jun 26, 2008
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    I have a 10 gallon pellet boiler with 200 gallons of pressurized storage that will not reach the set point of the boiler at 180 degrees.

    The boiler charges the tanks and the radiators pulls the heat out of the tanks.
    Boiler supplys the bottom of the vertical tanks and is returnd to the boiler from the top of the tanks. Same for the Radiators.

    I mean the house is warmer than it has ever been.

    I just want to close that differential.

    Any and all ideas welcome.
     
  2. skalor

    skalor
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    What type of boiler? I ask because if it's self modulating it may be getting 180° water if it's pulling from the top of the tank. Which also begs the question of where are you measuring the storage temp. You should really be pulling water from the bottom of the tank to maximize the delta in the boiler. Also, if your house is able to maintain set point I wouldn't worry so much about having 180° water. Unless your boiler is still running full load then maybe something is wrong. If the boiler is idling I think either you are measuring the temp in the wrong place or your gauge is off.
     
  3. maple1

    maple1
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    Not sure how much it is impacting your situation, but your boiler should be supplying to top of storage & pulling return from the bottom.
     
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  4. ejhills

    ejhills
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    upload_2019-1-10_7-45-14.png
    This should be stratifying beautifully, but at best it 10 degrees off.
    each of these tanks have coils but are not getting used.
    Given the plumbing, reversing the boiler pump makes little sense, with another bigger pump right next to it running in the opposite direction.
     
  5. maple1

    maple1
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    For a whole system to work up to its capabilities, the zones should be supplied with the hottest water in the system, and the boiler should be supplied with the coldest. Yours isn't doing that.
     
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  6. ejhills

    ejhills
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    Those are 2 100 gallon boilermates.
    Hmm I might have to decouple the storage and use the coils....
     
  7. maple1

    maple1
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    I'm not sure what that would accomplish?

    If the setup is heating the house well as-is, I might be tempted to just leave it.
     
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  8. salecker

    salecker
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    Your storage needs to be re plumbed to work properly.
    Storage usually isn't used with a pellet boiler.
    Just curious as to the thought behind using storage with your pellet boiler? Maybe you have a good reason and others could benefit from it.
     
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  9. maple1

    maple1
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    We also have no idea how much heat your house needs, and how much your boiler makes.

    If the boiler won't make a fair amount more than the house needs & uses, storage use would be questionable, and the inefficiencies & stack losses at the higher temps you would be pushing when trying to fully charge storage might be enough that the boiler just doesn't have the extra BTUs to push that last amount.

    Storage will pull more BTUs out of your boiler when starting with cold storage, than it will when you have storage almost up there and are trying to raise the temp that last bit. When burning every day, I usually don't finish a second lap of charging. Which leaves me with maybe 180 at the top, and 160 at some point lower down. Not sure how hot you are getting yours?
     
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  10. warno

    warno
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    When did this problem arise? Or was it always there and you're looking for a solution?
     
  11. ejhills

    ejhills
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    This is a Mini Boiler from Woodmaster.com. A pretty simple unit. So it is basically a wood boiler. The manufacturer suggests a min of 50 gallons of buffer tank. I had these Boilermates attached to the Tarm so I just moved them over. The chimney is very tall and I've had to trim the turbulators down for 20 inches to 13 to get a decent burn. The Flue temp is about 290 - 310. Its a big house. 45' chimney with 12 cast iron radiators.

    https://www.woodmaster.com/product/mini-boiler/
     
  12. salecker

    salecker
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    I still believe you need to re plumb the tanks to work properly.
     
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  13. maple1

    maple1
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    Having to trim turbs on a chimney that tall sounds backwards to me. Usually turbs are trimmed when there is lack of draft. Which shouldn't be the case with 45' of chimney.

    Also sounds like a big heat load from what you said. The boiler might have its hands full just heating it.
     
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  14. skalor

    skalor
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    Reversing the boiler circ makes perfect sense to me. The returning zone water, the coolest water in the system, is fed directly to the boiler making for a higher delta. Also the hottest water is supplied directly to the heating zone providing the highest possible btu output on the rads. If there is a differential pressure between the two it will either supply or draw from the buffer tanks. Really not any different than this article from Siggy himself.


    PM1014_Siggy-fig-5_slide.jpg
    https://www.pmmag.com/articles/96765-alternate-methods-to-pipe-a-buffer-tank
     
  15. skalor

    skalor
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    Storage is useful for any boiler that has a heating zone requirement less than the lowest possible boiler output.

    It definitely needs to be re-piped.
     

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