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Harman Invincible Insert

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by jhoov76, Dec 19, 2005.

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  1. jhoov76

    jhoov76 New Member

    Joined:
    Dec 19, 2005
    Messages:
    4
    Hey,

    I just recently purchased a Harman Invincible pellet stove second hand from a guy I work with. I'm sure many of you are muttering something about me being one of those newbies that causing the pellet shortages in New England:eek:) - I would be to. I've been impressed so far with how much heat this stove can put off. I am also learning that the right pellet makes ALL the difference. I have couple questions about the stove and about heating with pellets in general.

    1st question:
    The controls on the Harman provide control over the
    -pellet feed rate
    -stove temp/room temp control (ranges from Low to High for both room & stove temp)
    -Temperature setting (dial has a range from 50 - 90 degrees and is numberd 1-7)

    I have the manual for this model but I'm still a bit unclear on several things. According to the manual, when I set it to run off "stove temp" the cumbustion and distribution fans should remain constaint after the appropriate stove temp is reached and then I just need to find the appropriate feed rate. What I don't know is if the Temperature Setting gauge has any affect at this point. I suspect that it does b/c when I crank that gauge up, it seems that the feed rate increases. Anyone know for sure about this?

    2nd question:
    Does anyone have experience with what the pellet consumption should be like on this model? I am burning anywhere from 1-1/3 - 1-3/4 bags per 24 hours. I'm able to heat an entire 2200 sq ft house with that but I don't know if that's a lot of pellet or not. If it is excessive, is there anything I would need to replace or repair to help with this since it was not purchased new?

    3rd (and final) question:
    I'm able to heat my entire house but not evenly. I have an old farm house and it's basically a collonial, 2 story house with about a 600 sq ft single store attachment. The attachment is the hard part because I only have a door way to blow heat through. I've been using a couple fans to try to circulate heat but I'm very curios what's available for this purpose, what resources are out there and mostly what you all are doing to solve such a problem.

    Thanks much for any and all responses

    Jim the Newbie

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  2. stovemanken

    stovemanken New Member

    Joined:
    Nov 30, 2005
    Messages:
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    Jim:

    The STOVE TEMP mode is a fully manual mode. There is a single knob for both ROOM TEMP and STOVE TEMP modes, but 2 dials, by that I mean the temperature settings (50 degrees to 90 degrees) and 1 to 7 for STOVE TEMP mode.

    In STOVE TEMP mode, if you are set on 4 and you are cold, set the stove for 5. If the stove is set on 4 and you are hot, set the stove on 3.

    You are correct that the distribution blower will stay on whatever setting you select between (L) low and (H) high and will stay there, regardless of the temperature in the room.

    The numbers (1-7) are tied to specific temperatures the probe in the exhaust sees. (The ESP [Exhaust Sensing Probe] which is a thermister.) A 4 setting is a temperature lower than a 5, etc.

    The control board will match the feed rate (and the combustion blower voltage) to achieve the ESP temperature that corresponds to the number (1-7) selected by you.

    If you noticed, the instructions for setting the feed rate have you place the stove in STOVE TEMP mode at the maximum (7) setting for 1 hour, then see if you have 1" of ash on the front of the burn pot. If you are pushing hot pellets off, or if you do not have 1" of ash, you must decrease the feed rate. The maximum feed rate is mostly dependent on pellet quality, but altitude and venting configuration also matter.

    Example: Feed rate of 4 might mean 20 seconds of feed, 40 seconds off. You have selected a STOVE TEMP mode setting of 4. You have an excellent pellet, so the stove can achive the required ESP temperature by feeding only 12 seconds with a voltage to the combustion blower of 90v. Now you turn the stove up to 5, and the stove needs more pellets to achieve that ESP temperature, so it feeds 15 seconds and the voltage increases to 95v. Obviously, that will look like the bigger fire that you see. Notice that the ACTUAL feed rate is a PORTION of the MAXIMUM feed rate, for the maximum rate is not needed.

    Question #2
    Your pellet consumption seems quite normal. The Invincible Insert is a 55,000 Btu stove. I believe you are saying average consumption is 1-1/2 bags per day. 60 pounds x 8300 Btu per pound = 498,000 Btus for a 24 hour period. 498k divided by 24 hours in a day is 20,750 average Btus per hour; less than 1/2 the stove's potential output.

    Question#3
    You have the "single-point heat source" conundrum. Since the stove is not ducted like a furnace, it must rely on its 135 CFM blower and convection to move the heat around the house. There are many folks that have postings here that talk about the ability of a stove (any fuel) to heat their whole house. Even the most enthusiastic of those folks will admit that convection is not the greatest way to move air. They will also admit that the room with the stove is ALWAYS warmer that the room farthest away. Fans don't help much, because moving air will always feel colder than stationary air.

    SMK
  3. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
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    49,657
    Loc:
    South Puget Sound, WA
    Nice summary Ken. I've always been confused about running the Harmon.
  4. jhoov76

    jhoov76 New Member

    Joined:
    Dec 19, 2005
    Messages:
    4
    Ken,

    Thanks for all the great info. I'm still processing some of it but that's a huge help. If I understand you correctly, the feed rate is something that should only have to be set once for each pellet type I buy. Then, I should only need to adjust the temperature setting and the stove temp dial to get the desired room temp. Did I understand you correctly?
    I didn't realize that there is a sensor for both stove temp mode and room temp mode. Wow I have a lot to learn! Thanks again for all the excellent feedback.

    Jim
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