Getting ready to upgrade

UPmqt Posted By UPmqt, Oct 8, 2018 at 11:28 AM

  1. Highbeam

    Highbeam
    Minister of Fire 2.
    NULL
    

    Dec 28, 2006
    16,009
    3,950
    Loc:
    Mt. Rainier Foothills, WA
    As treehouse used it, batch burning a pellet boiler just means running the boiler at high output (or most efficient output) level constantly to reheat his storage. Then shutting off until the storage cools. That is different than modulating pellet boiler output to try and match the heat load which varies and is less efficient.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  2. Sparky978

    Sparky978
    Member 2.
    NULL
    

    Jan 18, 2015
    43
    8
    Loc:
    Ma
    So how does he run his PB at 100% output constantly? I would think that it would start to modulate at some point. Unless he actually watches it and when it starts to modulate he sends it into burn out mode.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  3. maple1

    maple1
    Minister of Fire 2.
    NULL
    

    Sep 15, 2011
    9,853
    2,077
    Loc:
    Nova Scotia
    'Then shutting off until the storage cools'
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  4. nhtreehouse

    nhtreehouse
    Member 2.
    NULL
    

    Feb 11, 2017
    64
    14
    Loc:
    New Hampshire
    Hi @Sparky978 ,

    I have the Windhager set to maximum boiler setpoint, which I believe is 176::F. I have a conventional Thermovar, a LK823 setup, much like you would setup any wood boiler hooked up to storage. Plumbing is really straightforward. I've got mine piped with 1" copper, and run an alpha on the lowest constant speed setting. Mine runs about 7 gpm at 14 degrees ::DTT.

    I turn on the pellet boiler when the top of the tank reaches close to the ODR target, which obviously fluctuates with the outdoor temp. Once the boiler fires, I keep it on until the return temperature of the pellet boiler reaches 160::F.

    The boiler's output temperature isn't the 176 number but rather determined by the flow rate and the regulating temperature of the Thermovar. I see the Windhager settle in at around 160-162 for a burn. Towards the end of the burn, the boiler temp does rise as the return temperature rises. But it happens quickly, as the boiler is putting energy into your storage and moving the thermocline down.

    I've got a 150 (15kW or 51kBTU/hr) unit and about 120 gallons of storage. My run times are around 2.5 hours on average.

    I don't know if a image would be helpful or not, here is the last complete burn:

    upload_2019-3-10_14-9-22.png

    bT = boiler temp (ya know, the hot side)
    LKAB = Boiler Return (ya know, the cold side)
    LKA = The "A" port on the LK valve, coming from the bottom of storage.
    pBR = crappy beer, or if you're a hipster, it's the pellet boiler return. This sensor is over in the tank several feet of piping away.

    The system which logs the data only logs when the boiler is being called to heat the tank. Those extraneous lines are the graphing software trying to connect the dots from the last full burn to the next.

    Anyways, it works really well. Super reliable and I've had no issues with it. In the biomass sticky there are some control systems like this described. I'm certainly not the first to do this.
     
  5. nhtreehouse

    nhtreehouse
    Member 2.
    NULL
    

    Feb 11, 2017
    64
    14
    Loc:
    New Hampshire
    Oh, and I should have said ... because the boiler never reaches the setpoint, it runs wide open at 100%. It may modulate a little at the very end of the burn as the return temp increases, and the thermovar opens. But if it does, it only modulates for a few minutes as that pellet boiler return temp is really moving fast.
     
  6. Sparky978

    Sparky978
    Member 2.
    NULL
    

    Jan 18, 2015
    43
    8
    Loc:
    Ma
    Thank you
    Now I have a better understanding of how your system works. Very helpful.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  7. huffdawg

    huffdawg
    Minister of Fire 2.
    NULL
    

    Oct 3, 2009
    1,447
    114
    Loc:
    British Columbia Canada

    Care full with that one , I spray foamed my pex lines with closed cell foam about 8 years ago. I'm now seeing a nice melted path above my pextubing. I'm thinking the foam is starting to break down.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  8. salecker

    salecker
    Minister of Fire 2.
    NULL
    

    Aug 22, 2010
    926
    288
    Loc:
    Northern Canada
    I would be talking to the spray foam guys about that.
    Mine are still good after 8 yrs no sign of any melt
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  9. huffdawg

    huffdawg
    Minister of Fire 2.
    NULL
    

    Oct 3, 2009
    1,447
    114
    Loc:
    British Columbia Canada
    Is your ground dry?
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  10. 3fordasho

    3fordasho
    Minister of Fire 2.
    NULL
    

    Jul 20, 2007
    805
    213
    Loc:
    South Central Minnesota

    I get all set to go with foam in trench and then I see stuff like this.. I wonder if it's got something to do with the expansion/contraction cycle the pex goes through as water temp changes. Regular and oxygen barrier pex move quite a bit. pex al pex is much more stable so I was thinking of using that in the trench.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  11. salecker

    salecker
    Minister of Fire 2.
    NULL
    

    Aug 22, 2010
    926
    288
    Loc:
    Northern Canada
    Hi
    I am not sure what you mean by is the ground dry?
    We live in the bottom of an old glacier formed lake,300+ ft of clay.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  12. Seasoned Oak

    Seasoned Oak
    Minister of Fire 2.
    NULL
    

    Oct 17, 2008
    6,297
    1,303
    Loc:
    Eastern Central PA
    Bingo. Cant expect much heat from green wood. Id try to get few boiler loads of certified dry wood and see what difference it makes first. I wouldnt be surprised if wet wood decreases performance by 50% or even more depending just HOW wet it is.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  13. huffdawg

    huffdawg
    Minister of Fire 2.
    NULL
    

    Oct 3, 2009
    1,447
    114
    Loc:
    British Columbia Canada
    Mine is on top of clay also, the 3 ft of fill on top I think gets quite saturated during wet spells.. I guess I won’t know what the problem is till I dig it up .
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  14. salecker

    salecker
    Minister of Fire 2.
    NULL
    

    Aug 22, 2010
    926
    288
    Loc:
    Northern Canada
    All clay here.
    Some people make the mistake of digging a basement here and back filling with gravel.Then wonder why they have a leaky basement.I back filled my trenches with dry clay and my basement.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...

Share This Page