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Burning a Harman on low continuously?

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by MCPO, May 10, 2008.

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  1. MCPO

    MCPO Minister of Fire

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    western Ma , close to NY state border
    What effects if any is encountered by burning a pellet stove on it`s lowest setting? When I leave my P38 on low the fan doesn`t run but comes on occasionally for a few minutes , then off for longer periods.
    The small fire (1"-1-1/2" high flame) looks to be burning correctly and the stove itself remains quite hot.
    I posted a similar thread a few days ago and it got a lot of hits but no replies. I guess that either no one runs his P 38 at the lowest setting or they are OK with the fan cycling on and off.
    I just feel like the stove is hot enough at the lowest setting to maintain a constant slow rate of air flow.

    Added later on the day:
    OK, I disconnected the distribution fan from the stove controller and connected it to a separate fan speed controller. Now I have total control over it and can run it continuously. I`ll just have to try it and see for myself I guess. When it gets colder this evening I`ll give it a go and report back.
    John

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  2. FredJ

    FredJ New Member

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    What Harman do you have?
    What speed controller did you use and where did you get it?
  3. MCPO

    MCPO Minister of Fire

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    I`m using a Lutron FS-5E-IV solid state fan speed controller. I bought it at my electrical wholesalers but these are also commonly used in paddle fan installations and are not hard to find or are they expensive. ($13.00) Since the stove controller is solid state it should be just fine. I ran it for two hrs (not burning the stove) earlier. I`ll be testing it later with the stove operating.
    John
  4. MCPO

    MCPO Minister of Fire

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    Loc:
    western Ma , close to NY state border
    I burned the stove on # 1 (fan running constantly on low) through the night. Finished basement (900 sq ft) maintained temp at 72 degees with some heat going upstairs ( plus floor vents) to first floor which stayed at 69 degrees. The oil furnace never came on.
    It went down to 37 last night and I know the finished basement would have been around 64 or less and the heat would have definitely kicked on for the first floor at some point during the night or morning.
    OK in summary, I can now conclude that the Harman PP38 pellet stove can be run successfully at the lowest heat setting with the fan running continually with the use of a simple $13 fan speed controller. It allows for the stove to be set at the minimum burn while constantly distributing heat . I feel this is most desirable for heating in the fall and spring and on cooler days and nights when the stove does not need to operate at higher than needed settings just to keep the distribution fan going.

    And by adding a simple $1 single pole double throw (3 way switch ) you can simply switch back and forth to the original on board fan speed control . That might well be necessary for those who utilize a wall thermostat that pushes the fan and burn rate to turbo speeds on the call for heat.
    UPDATE: Oh yeah, the new speed control really works as I hoped it would but the single pole double throw (3 way switch) as mentioned in the above paragraph didn`t quite work out as I first thought it would , probably because of the neutral conductor (white) arrangement within the on board controller that might be allowing feedback . The fan runs on full speed when switched back to the stove controller . Maybe a double pole double throw switch would work by isolating the neutrals but I`m just gonna leave the new added fan speed controller alone as it does what I originally set out to accomplish since I won`t be using a wall thermostat. I`m not really too keen on messing with and burning up that solid state stove controller. I would imagine it`s a costly item to replace.

    John
  5. FredJ

    FredJ New Member

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    John,

    This is leaning toward a direction I've though about for a while, except your switch is a manual on/off. What I would really like to see is a diagram of something using a relay/triac/transistor ( Which ever is needed, I'm not a electronics wiz) that would only switch over to the added fan control when the onboard went to off. This way the stove would control the Dist fan as usual except when it said "no fan" then the added control could take over until the stove again said "fan on". Of course this would also involve tapping a leg of the combustion fan to verify that was on, (another transistor/relay?) if not, dont turn on the 1st relay to the Dist fan. Otherwise the Dist fan would run with the stove off. This could all be done without any hard wiring of the stove, just use the existing slide on/off connectors at the fans. ( easy to remove the "add-on" in case of a service call)
  6. MCPO

    MCPO Minister of Fire

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    Hi FredJ ,
    I`m actually a retired electrician with limited electronic tech skills so I won`t be much help there.
    The manual control will work fine for me. Maybe someone with good electronic knowledge will chime in with some answers for you.
    Good luck,
    John
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