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Harman pb105 shut off seems slow

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by gordon, Dec 7, 2012.

  1. gordon

    gordon New Member

    Joined:
    Dec 7, 2012
    Messages:
    1
    I am working with a pal on a harman pellet boiler. Just getting it to run after installation in series with an existing oil fired boiler.
    1- the harman set at 165 degree water temp still feeds pellets at 175+ degrees water temp. It will stop if you turn feed rate down to 1 and turn hi temp down to say 140 degrees.(not using outside temp reset)
    Q- is there a time frame ,that makes the stove stop slowly, programmed in?
    or do I have a dip-switch not right on control board or perhaps an aquastat sensor problem


    2- the circulator, water makeup/feed, expansion tank, and such are at the original oil fired boiler, which are at a 2 foot higher level than Harman PB and approx. 15 foot of piping away . (in a different room) What is happening at startup of PB is the water pressure reads 20 pounds and by the time it gets to 180 degrees it is just shy of 30 pounds and once opened pressure relief. These readings are from top gage on harman PB. meanwhile at the other boiler, near the expansion tank, it reads just a bit over 20 pounds there.

    Q- do i have an air pocket giving this problem, or do I need a bigger (or an additional) expansion tank near PB. Or is the expansion tank now too small for the added water of both boilers? It makes no sense why the pressure is different at both boilers.( Assumption they are both good working gages). All the piping is connected in series.

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  2. iceguy4

    iceguy4 Minister of Fire

    Joined:
    Nov 16, 2011
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    Loc:
    Upstate, NY

    I just found out recently the PB has 50 gallons of water in it...you will need another expansion tank, do yourself a favor and add another air scoop and air bleeder too (I got a kit..$79 or so) Mine has a manufacture date of 11/2012 so its new. Mine too will not stop all at once and will slowly stop delivering pellets...
    as for your " assumtion" those guages when they get older will become less relyable.
  3. katman

    katman Member

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    Jul 7, 2008
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    Loc:
    annapolis md
    I'm not an expert Gordon, but I have my low set at about 145 and high at 185. Set to auto mode. I have not hooked up the outside air sensor. Works fine with a gradual shutdown as it approaches the upper limit. My 105 is in a remote building with total of about 135 feet (one way) of 1 1/4 inch pipe. I use the expansion tank, feed on the oil boiler. I do not use the circulator on the oil boiler. I put a circulator (and air scoop) on the pb105 and control it with the house thermostat. For the difference in pressure you are seeing do you think the water is moving?
  4. Delta-T

    Delta-T Minister of Fire

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    Feb 27, 2008
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    3,125
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    NH
    just an FYI, it is not uncommon for the combo guage that comes with the PB105 to be inaccurate in terms of temp. I've seen it be off by 10-15 deg out of the box. You might want to try and verify the water temp another way just to rule that out.
  5. BoilerMan

    BoilerMan Minister of Fire

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    1,624
    Loc:
    Northern Maine
    I'd not trust the oil pressure/temp gauge. The relief valve opening is as good of indication that you need. More expansion tank is needed. I instralled a PB105 for my uncle a couple of years ago, 145/185 also. It will get in the 195 range with no load.

    TS

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