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How Your Harman Works -what your manual doesn't tell you..

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by lbcynya, Sep 30, 2012.

  1. lbcynya

    lbcynya Feeling the Heat

    Joined:
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    Loc:
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    Thanks Mod for correcting the title!

    Now, let's have some fun and stay warm!

    How your stove works - The facts are pretty straightforward, but how you get people to properly interpret the facts is the hard part. It's your toy, run it the way you want as long as you understand what's going on behind the scenes! Everything noted below is based on me seeing what the stove is doing via the Harman diagnostic tool during the various operation methods. I get to see feed rates, max feed rates, current ESP temps, ESP set temps, room sensor temperatures, room sensor target temperatures, knob positions, switch positions, etc.

    Here are the facts:

    Stove temp - 100% driven the the ESP (temperature probe in stove exhaust flow). Temp dial corresponds to a fixed ESP temperature. For simplicity, let's assume a setting of 3 = 300 degrees ESP temp. The stove will ramp feed up/down to always be as close to 300 degrees as possible. In stove temp the stove doesn't care what the room temp is, only the ESP temp. The room might be 60 or 90 degrees doesn't matter, all it cares about is maintaining an ESP temp of 300.The stove will not shut off in stove temp regardless of whether the igniter switch is set to auto or manual. Stove temp, switch to manual - I call this fireplace mode. Distribution fan will not turn on unless the temp knob is set to 5 or higher. This is designed to give a nice fire, but not a ton of heat in the room. Most goes up the chimney. Stove temp, switch to auto - distribution fan operates normally to push heat into the room, regardless of stove or room temperature. There is a caveat to this, if you have your room temp set to 1 (very low) then the distribution blower might shut off because the ESP temperature is below the lowest setting allowed for the distribution blower to run.

    Room Temp - The stove is 100% driven by the room temp sensor. The stove will automatically adjust feed and ESP temp to achieve the room temp set point. Once the set point is reached, the stove will slowly throttle up/down to maintain temperature. If it's 20 degrees outside, your heat load is high and the stove will feed more pellets to get the ESP temp hot enough to maintain room temperature set point. If it's 60 degrees outside, the stove will feed as little as possible and keep as low an ESP temp as possible to maintain room temperature. Igniter switch to manual, stove will go into maintenance burn in between calls for heat - prevents igniter cycling, might use a few more pellets in this mode...maybe... Igniter switch to auto, stove will initiate the shut down process in between calls for heat - igniter could cycle several times per day, depends on set point and heat load. If there is a call for heat during the shutdown process, the stove will start feeding pellets provided that the ESP temperature didn't go below the low limit. So, on really cold days, the stove might not shut off, even if it's on auto.

    The key to getting room temp to work is placement or "calibration" of the room temp sensor. This is a tricky subject due to the sheer number of variables that can contribute to success or lack there of. Ideally, you want the tip of the probe in an area that is not subject to drafts, direct sun or areas that could lead to heat soak from the stove or areas that make it tough to calibrate like basement concrete floors. Ideally, you want the probe on an inside wall (no drafts), away from concrete and fairly far from the stove, even if you need to extend the wire. If the probe is where you are, then the stove can work to keep an even temp that works for you. If your set on having the dial temp correspond with the room temp, you will need to experiment for a while until you find the most reliable place for the probe to stay.

    Alternatively, you can place the probe in a "stable" location and simply adjust the temp knob to achieve the most comfortable room temperature. Maybe 78 on the temp knob gives you a steady 72 degrees, no worries, just keep in mind that the probe reads 6 degrees high and do the simple math if you feel like adjusting the temp.

    Either way, you need to be smarter than the probe, since it does nothing more or less than reading the temp where it resides. ;)

    ;ex If either option above doesn't suit your needs, you can ditch the way Harman wants you to run the stove and install a simple thermostat to control the room temperature. See my signature for details on the Skytach model or see post #8 below or the traditional Harman recommendation.

    And more...

    Feed Rates - Feed rate is controlled by the stove ESP. The stove will select a feed rate based on the actual temperature and target call for heat. The larger the temperature delta (actual room temp vs. target room temp), the greater the feed rate will be. 10 degrees would be a large delta and the stove would feed to reach max ESP temp of about 500 degrees depending on stove model. A 2 degree delta might only result in a feed rate of 20 seconds per minute even though the feed rate max dial is set to 4 (or 40 seconds per minute). The stove can vary the feed rate between 2.5 seconds per minute and the max feed rate you set. A feed rate of 6 would represent continuous feeding if the ESP wasn't seeing sufficient temperatures to satisfy the call for heat.When up to temp the stove will regulate itself form 2.5 seconds per minute of feed up to the limit you set.

    Feed rates can lead to incomplete combustion comes in 2 forms:

    1. Pellets spilling over the edge of the burn pot before they are reduced to ash.
    2. Smoke.

    Relative to #1 - when you run the stove wide open (stove temp setting at 7), the burning pellets should come no closer than 1 inch from the edge of the burn pot. You should have burning pellets and about 1" of ash before the edge. If pellets are bulging and close to the edge, you might not turn them to ash before spilling over the edge, wasting energy. If the burn line is too close, dial the feed rate back a bit, may by 1/2 of a number (i.e. 3.5 to 3). The stove doesn't run wide open once everything is up to temp, so this is only for scenarios where, for instance, the room is 65 and you want it 75 degrees or you turn the temp dial all the way clockwise (just don't walk away for too long or you'll bake yourself...).

    Relative to #2 - smoke is also a sign of incomplete combustion, meaning that there is more fuel than air supplied by the combustion blower. This too should be evaluated when the stove is running WIDE OPEN. At night with a flashlight, you'll always see smoke. During the day, smoke is rated based on opacity or how easily you can see through it. Startup might be 50% opacity or fairly heavy smoke. If you are 10% or less (barely visible), that's reasonable and you aren't really wasting anything. If you have to struggle to see it, you're probably good. If you can easily see smoke and your flame is HUGE, try dialing back feed rate a bit to bring the air/fuel mix back into a more efficient range by dialing it back by 1/2 of a number (ie 3.5 to 3). In most cases, you don't want to be below 3 or much above 4. You'll also want to recalibrate after changing brands of pellets since the blend and size of pellet will cause it to burn/feed differently.

    Setting your feed rate too low doesn't save pellets and stove performance will suffer since your inhibiting the ESP from reaching target temps. Setting your feed rate too low is like putting a brick underneath the gas pedal of your car.

    Don't be tempted to set your feed rate too low.

    So there's the facts, interpret away...

    Cleaning tip - During your periodic cleaning, turn the knob to "test" while you clean the firebox to evacuate the ash out the chimney vs. into your room.
    glen1971, Bigjim, Peterfield and 5 others like this.

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  2. lbcynya

    lbcynya Feeling the Heat

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    For the time being, I'll use post #2 to link to some topics/ideas/etc. that can be useful or fun if your snowed in...

    Go to the link below if you are interested in testing the heat output of various pellets. Since Harman stoves have an ESP (temperature sensor in the exhaust) you have to cheat a little to override the ESP in order to let the pellets determine the heat output. Don't get me wrong, the ESP is, in a lot of ways, what makes a Harman a Harman, so this is just to have fun if you want to jump on the pellet testing craze.

    http://www.hearth.com/talk/threads/...to-test-different-pellets.81021/#post-1035165

    Auto or Manual???? - go to the link below for a thread that touches on this option.

    http://www.hearth.com/talk/threads/manual-or-auto.82295/#post-1052608
  3. tsmith

    tsmith Minister of Fire

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    Thanks, very informative.
  4. GrahamInVa

    GrahamInVa Minister of Fire

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    Eastern, Virginia
    Wow! Thanks! I just got done installing a P61A and I was a bit confused about the whole "Room" and "Stove" temp. You cleared it all up! And did a much better job than the manual!

    Thanks! ;)
  5. Chain

    Chain Feeling the Heat

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    Quick question...Is it okay to start the stove with auto igniter in Room Temp., allow the stove to cycle up and burn until the distribution blower comes on, burns for a bit (say 10-15 minutes) then turn the igniter to manual so as to not cycle the igniter throughout the day? In other words avoiding a manual start with gel, but then flicking to manual simply to avoid cycling the igniter all day? Make sense?
  6. Melissa220

    Melissa220 Feeling the Heat

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    I have been doing that each time I have used the stove in the last couple weeks. You will find that your room temp may be a bit higher than you have the temp set on the stove, but you can compensate for that by reducing the temp on your stove I find if I set for 65 room temp, start on auto and switch to manual, that my room temp is about 3 to 5 degrees higher! And you don't have to wait 10 -15 minutes t switch to manual. You can do this as soon as you have ignition and the igniter turns off.
  7. lbcynya

    lbcynya Feeling the Heat

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    It's even easier than that, just quickly flip the switch from manual to auto and back to manual and you're done. Just verify your igniter light is on and walk away. Simple. :)
    gbreda likes this.
  8. Melissa220

    Melissa220 Feeling the Heat

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    So switching to auto ignite, even momentarily, starts the ignited? Nice. Thank you ibcynya.
  9. TheMightyMoe

    TheMightyMoe Minister of Fire

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    Loc:
    Fairbanks, Alaska.
    Just a re-post that has been referred to many time...

    All Harman pellet units can utilize a setback thermostat. The thermostat must be:

    1. Millivolt compatible
    2. Have gold contacts
    3. be low voltage
    4. be low current


    Harman reccommends the following Honeywell units for this use:

    RTH230B
    RTH6300B


    If there is a jumper between Rh and Rc, it must be removed from the terminal block of the thermostat. The thermostat must be connected in series with the room sensing probe using the Rh and W terminals of the thermostat. Except with the P38, which has no room sensing probe, the set-back thermostat MUST be used in conjunction with the room sensing probe.

    there are two modes of operation as well:

    Occupied Mode: (someones home)
    Set the thermostat to its max temp setting. The stove room-sensing probe will control room temperature, so set the desired room temp on the stoves temp dial.

    Unoccupied Mode: (noones home)
    Program the thermostat to the desired set-back temp. When the thermostat opens (is satisfied) the stove will go into a 4-blink status. If the stove is a auto-ignite model and the auto/manual switch is in auto, the stove will shut down. When the thermostat closes (calls for heat) the 4-blink status will reset and the stove will ignite.
    If the stove is a manual ignition model, or an auto-igniting unit with the selector switch set to manual, the stove will go into the 4-blink status when the thermostat opens (is satisfied) and the stove will go to a minimum burn and stay there until the thermostat closes (calls for heat). When the thermostat closes, the 4 blink status will reset automatically.

    Consult your owners' manual for a description of the 4-blink status. This error occurs when the contril board senses the room sensing probe isnt connected or has failed. This happens with the thermostat in series, since when the thermostat opens (is satisfied), there is a loss of continuity in the room-sensing circuit. The 4 blink status automatically resets when the board recognizes the room-sensing probe has been reconnected (ie: when the thermostat closes and calls for heat).
  10. MCPO

    MCPO Minister of Fire

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    Great post! I find the Harman ESP to be reasonably accurate ,dependable, and quick to respond. And Harman controls are so easy to use. (at least in the P-38)
  11. AndrewChurchill

    AndrewChurchill Minister of Fire

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    In reference to setting the feed rate. You should place a large heating load on the pellet stove/furnace/boiler and set the feed rate to 6 initially.

    Then you watch the burn pot. If unburned pellets are dumping into the ash pan then back off the feed rate to 5 1/2 and watch again.

    Repeat this procedure dropping the feed rate in 1/2 unit increments until you have ash appearing about 1" from the edge of the burn pot.

    If you change pellets you may have to adjust the feed rate again.

    Setting the feed rate in this manner allows the control board to satisfy the heating demand in the most efficient manner.
  12. CTBossfan

    CTBossfan Member

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    Thanks for posting I've read a lot on these boards but I don't think I read about your cleaning tip before thanks for all the info.

    Is there any heat ouput advantage to running the blower on high or is it just better distribution of heat? I guess my question is would there be any increase in heat output with blower on high or does it have no effect?
  13. Chain

    Chain Feeling the Heat

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    Loc:
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    Nice! Thanks for the very helpful info and for replying to my question. Since this will be my first season with the Harman P61A, I'm still trying to decide what mode I'll run it in when I'm at work during the day. Based on what you're telling me, I think Room Temp. mode with Manual igniter will work best. Feed rate at 4 and the temp. set at about 65....Should keep my 1800 sq. ft. very open floor plan ranch nice and toasty. Thanks again.
  14. Cincinnati Kid

    Cincinnati Kid Feeling the Heat

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    I believe when adusting Feed Rates, they only apply when in Stove Mode. When operating in Room Temp, the Feed Rate is done automatically and adjusting the Feed Rate has no impact.
  15. TheMightyMoe

    TheMightyMoe Minister of Fire

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    The feed rate will affect the maximum possible feed rate in room temp mode. The stove can't tell if burning pellets are falling off the burn pot.
  16. afranch

    afranch Member

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    Loc:
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    In my experience where one wants the feedrate can depend on how one is using the stove and the prevailing conditions of the stove's location. Maybe my thinking is flawed but empirically I have accomplished my goals with a lower than recommended feedrate that appears to save pellets. lbcynya's post is giving me some ideas however, about other ways I can try to operate the stove that might be more efficient:

    The Harmon Accentra is in finished basement & is used to:

    (i) heat the basement on demand when people are there

    (ii) heat stone floor above that gets cold on the feet (yes convective heat does not directly/efficiently heat stone, however basement has very low ceiling & we find warm air in the basement will of course over time bring the floor system above into thermal equilibrium, so it works). We also crank a small woodstove on the main floor for speedier floor/masonry heat storage (this is an old farmhouse so when it's very cold this helps a lot).

    (iii) augment heat pump above to keep emergency strip heat from ever coming on. This is the first winter we will have the heatpump....we had an old "Apollo" system that used an ancient propane tankless water heater in conjunction with an old air handler/old condenser that finally died. We plan to use the new heatpump primarily for AC in summer, but also to even out heat in cold seasons. Also we plan ultimately to rent the house and wanted something that would work well for renters.

    What I found my first season is I was going through pellets at an alarming rate when I calibrated the feedrate according to the recommended 1" methodology. Even when I turned the temperature setting down it still seemed to use a lot of pellets with the 1" rule. Fearing running out of pellets I began setting the feed rate low (except at peak times of need)...typ rate setting of 2. I found that for my situation it gave me the desired effect during off peak heating times and used less pellets.

    After reading lbcynya's post I can see some of the waste I had probably comes because I have the probe about 36" high up a table leg in a drafty basement where the air stratifies. Since a lot of the heat assistance I want is on the floors above it may be I'd be better off either raising the probe on the wall or using stove temp for assitance only then switch to room temp for when the basement is occupied. Perhaps then I could use the recommended feedrate all the time and get better overall efficiency for my needs. I'm going to think more about this and will also check and see if anyone has any ideas to add. Thanks for the info Ibcynaya!
  17. abrucerd

    abrucerd Member

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    I can't believe I never thought of this or saw someone else mention this technique. Great tip!

    Another great & informative post. Thanks Ibcynya!
  18. lbcynya

    lbcynya Feeling the Heat

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    Nothing flawed with your logic, but lower feed rates will produce less heat. All the unique variables you (we) have will always make the perfect method a moving target. You might have bled the extra heat into another space or deeper into the structure which is hard to quantify, but it appeared as waste to you nonetheless. 1" method will insure you get the MOST heat out of your stove, but that doesn't mean it burns most efficiently. I would rather tune my stove by looking at the exhaust and turn the feed rate down until the opacity of the exhaust is almost zero (and no pellets are spilling...of course). While I can do this, others may have their exhaust exit above their roof line making this type of tuning almost impossible. In that case, the 1" method is safe and consistent. If you want to be conservative, you can get it steadily at 1" then dial back by 1/2 increment and call it good.

    For the sake of simplicity, if your heat loss is 20k BTU and you burn net 20k BTU worth of pellets (after stove efficiency loss) theoretically the room temperature will not rise or fall, regardless of the feed rate setting. It will also depend on how long the stove has been running and how much the heat loss varies (day vs. night). Lower feed rates will offer smoother transitions between call for heat and no call for heat, but too low could cause you to lose temperature during a cold snap at night. With all that said, if the spaces you want are comfortable and your stove can produce the heat you need during extreme cold, then your settings may be the most correct for your situation. That's why my explanation can only focus on the facts of the stove not the facts of your situation since they are unknown and extensive.
  19. Simon L.

    Simon L. New Member

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    Hello, and thanks for the tips. Very helpful.

    I have a problem with my Harman Advance-2 and I ask you some help :

    My distribution blower has stopped tu run last week (end of his life). (By the way, sorry for my english…)

    I’ve put a brand new one and a new problem’s begun :

    The new distribution blower run at max speed all the time. It never stops !!! And the speed doesn’t vary. I must to disconnect the stove from the electrical source to stop it….

    What happen ? I’ve connected the new blower properly (it’s very simple).

    So, If you know what is that, it will help me.

    Thanks
    Simon
    chriscarl likes this.
  20. afranch

    afranch Member

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    Terrific information and thanks for your kindness in sharing Ibcynya!
  21. lbcynya

    lbcynya Feeling the Heat

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  22. Brian F

    Brian F New Member

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    My Harman Accentra recently quit working in room temp but work normal in stove temp. When I switch to room temp the status light goes out. I do have a short line probe plugged into the back of the stove and it used to work without issues. Any suggestions would be appreciated. Thanks
  23. gambler13

    gambler13 Member

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    I was also told by my dealer and service technicians that you should run the stove in stove temp mode periodically to help burn off any creosote residue that could build up on the firebox walls. I do this once or twice a month for about an hour then switch back to room temp on my P43.
  24. kinsmanstoves

    kinsmanstoves Minister of Fire

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    The distribution fan does run in stove temp, not just over temp 5.

    Eric
  25. lbcynya

    lbcynya Feeling the Heat

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    Yes, when in Auto mode only...

    The joy/pain of this being a sticky is the fact that I can no longer edit the post to update it and keep it fresh as new issues arise. Hmmm...I thought stove temp manual/auto was already in there... Maybe the Mod's can help me out with this and unlock it...

    That being said, Stove Temp has 2 unique working modes - Auto and Manual via igniter switch selection. Stove temp AUTO will allow the distribution fan to run at most temperatures selected. Stove temp MANUAL will turn off the fan unless the temp knob is 5 or HIGHER to prevent the stove from overheating I would presume. Harman calls this "Fireplace mode" or something like that, to have a large flame without overheating the room. Either case, when in stove temp it will not shut down unless you turn off or it runs out of pellets.

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