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Double wall & Damper

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by rudysmallfry, Jan 18, 2013.

  1. rudysmallfry

    rudysmallfry Feeling the Heat

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    Screw it. After 6+ years of wondering if I should switch to double wall pipe, I'm going to try it. I had a 1/3 full load of wood practically overfire last week with the air completely shut. I'm sick of watching my single wall pipe at 400 while my stove is only at 250. Obviously there is way too much heat leaving the house than heating the room. I'm told this is common with the Hearthstone Heritage.

    Anyway, I'm going to include a damper with the new pipe. How far up the line do I put it? My set up is approx 24" from stove to elbow, then right angle to thimble in wall. I would look in the manual, but I'm at work and figure you guys know anyway.

    Also, I'm seeing a lot of the corrugated looking double wall pipe. Besides being ungodly ugly, does it serve any purpose over the old style smooth stuff?

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  2. pen

    pen There are some who call me...mod. Staff Member

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    Do you have a pipe damper in your single wall pipe now? How is double wall pipe going to help you keep more heat in the house?

    pen
  3. HDRock

    HDRock Minister of Fire

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    Ya ;?
  4. rudysmallfry

    rudysmallfry Feeling the Heat

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    Double wall won't help, but damper will unless I do not understand the function of a damper. No damper in my current setup. My logic is, after years and years, I still cannot fully load this stove without it overfiring. It's been checked for leaks and is tight as a drum. It has to be in the setup. I think it's time to do some investigative tweeking.
  5. pen

    pen There are some who call me...mod. Staff Member

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    Well, if you think you need a pipe damper, that can be added for about 10 bux to your current single wall pipe by simply removing it and drilling 2 holes.

    When it overfires, is the stove overheating ever or only the stove pipe? How high on the single wall pipe above the stove are you measuring the temp. What are you using to measure the temp?
  6. begreen

    begreen Mooderator Staff Member

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    If going double-wall usually the double-wall damper piece is 6" tall and goes right at the stove's flue collar.
  7. pen

    pen There are some who call me...mod. Staff Member

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    Somewhere I remember reading a recommendation of 18 inches up for a pipe damper?

    I think the reasoning was so that it was high enough above the stove that it wasn't too hot to use comfortably, regardless, that was in a document somewhere, perhaps it was a stove manual.

    Time to dig.

    However, mine is about 12 inches up in single wall.

    Also, to the OP, measuring about 20 inches up, when the stove is near it's redline temp that I'd want to see, I'll see as high as about 475 on the single wall.

    pen
  8. rudysmallfry

    rudysmallfry Feeling the Heat

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    When it overfires, it is just the temp in the stove pipe that climbs. Sadly the stove never gets that hot. I am measuring 18' above the stove on the pipe with a magnetic gauge. Guess I should just do one thing at a time. I'll try the damper with the single wall first.
  9. begreen

    begreen Mooderator Staff Member

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    How much connector is on the stove? How much chimney after that?
  10. pen

    pen There are some who call me...mod. Staff Member

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    More info about your setup as BG asked for would be helpful to give you advice but I agree with the one thing at a time sentiment.

    When putting that pipe damper in, put it in at a comfortable level would be my advice.

    pen
  11. HDRock

    HDRock Minister of Fire

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    What are you measuring these temps with ? cuz magnet thermometers can be 100 -200 degrees off
  12. rudysmallfry

    rudysmallfry Feeling the Heat

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    24" out of the top of the stove, 90 degree elbow, 26" to wall thimble. 18' class A chimney
  13. rudysmallfry

    rudysmallfry Feeling the Heat

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    I should add, the reason I know all the heat is going up the stove pipe is because it emits that awful burning metal smell when the fire is going too good. As soon as I shut down the air, temp drops and smell goes away. Overfire smell is coming soley from pipe, not stove.
  14. begreen

    begreen Mooderator Staff Member

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    By now I would have expected the stove pipe paint to be completely baked. You shouldn't be getting that smell.

    Your system is marginal for draft with the short rise on the stove and then two 90º turns. That effectively cuts the 18' pipe down to 13'. Double wall could help here by keeping the flue gases hotter, but a pair of 45's with a short diagonal off the stove might be as effective. Combining both would be the best. I see no need for a damper in this system. The problem appears to be marginal draft that is not adequate to establish a strong secondary burn. Adding some length to the class A is another option.

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