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Double vs. Single walled piping

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by ducker, Jun 11, 2008.

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  1. ducker

    ducker Feeling the Heat

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    This was kinda lost in my other thread:
    In my search for a good price on the install of a pellet stove I found out the following information.

    One dealer I talked to about pricing of piping - as he figured his costs for piping would be considerable less then the quotes I've gotten from other shops. And giving my situation/hearth he wouldn’t bother with the double lined piping, but instead go to a 6” black pipe right out of the back of the stove. The overall difference in cost between what he would be looking at for parts vs. other places was a good $200+

    Any reasons why I wouldn’t want to go this route? Ie. tell another installer I’d rather use just the standard piping not, the 4” double lined.

    His reasoning was because I have a whole brick hearth, including the walls, there is not any combustible material with in 18" of the pipe, and there for the 4" double lined piping is an added expense not needed.

    Any comments from the knowledgeable stove people out there?

    I believe this is my last bit of data I need to make my decision, thanks all for their input in my purchase.

    -Mike

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  2. ducker

    ducker Feeling the Heat

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    well where do these guys (an Authorized Harman dealer) come off stating they can do it when I read directly from the manual that Pellet Vent Pipe, must be used.

    Now they stated that they've done installs a ton of places, and the only reason to use the PV Pipe is that your clearance to combustibles is even smaller, but when you're on a full brick hearth, I don't see the added benefit at all.

    http://www.harmanstoves.com/doc/pp38plusm.pdf

    I don't get it...
  3. stoveguy2esw

    stoveguy2esw Minister of Fire

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    the unit was certified to be used with that type of pipe or with a "class A " woodstove chimney using "type L" or "type PL" pellet vent pipe to connect between them(which is not single wall) its not legal to install a pellet stove of that type with single wall woodstove pipe and the dealer who suggested it needs to get hit over the head with somthing. its illegal, against code and should never have been recommended to you in the first place.

    im sorry if i seem to come off harsh about this , its not directed at you , it just burns me up that a dealer would suggest somthing that wrong to a customer.
  4. ducker

    ducker Feeling the Heat

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    no, I don't feel as if it's directed at me at all. It's good to get more input like this. I just called the building inspector of my town to see if he had any insight. And well not too much it seems.

    "Pellet stoves need to be installed to the Mfg specifications; most of them that I've seen have a 3 or 4" exhaust off the back, which is either double walled or insulated in some way."
    but he didn't state there was a code one way or another :/

    Thanks for the feedback Mike.
  5. drizler

    drizler Minister of Fire

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    And the worst part of it all is the insurance angle. If by any far flung stretch the insurance company can infer that the stove was responsible for burning your house down ( and they surely will try); you will be fully screwed. Right or wrong anyone who knows the legal and insurance structure of this country knows you will be hanging in the breeze without a friend in the world. Its just not worth it in this day and age. Besides it doesn't cost much more to do it right . P vent isn't all that expensive compared to some of the corn rated vent folks need. No point in having insurance if they aren't going to pay for a loss.
  6. stoveguy2esw

    stoveguy2esw Minister of Fire

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    the applicable code for your installation is NFPA211. chapter 12 Para 1.1 states that solid fuel burning appliances must be listed and installed in accordance with their listing and this chapter. in laymans terms that means that for the installation to be code compliant , the materials, clearances and floor/wall protection must meet the standard which the stove was tested and listed at or it is not a valid code compliant installation.

    here is a link to a free readable (but not copyable) version of this code: http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=211

    just follow the directions agree to their terms and you can read the same code version which i am quoting from. in my line of work its handy to have and i urge anyone who is getting into this type of heating to read it and ask questions of their dealer/installer. also , feel free to ask me anything you wish on this , i'll help as much as i can.
  7. jtp10181

    jtp10181 Minister of Fire

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    I would stay away from that dealer. They have already shown their incompetence, don't test it.
  8. ducker

    ducker Feeling the Heat

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    wow... I'm just really surprised that this installer really seemed comfortable doing that type of install.
    I could really see what you were talking about in regards to the code. I could look at he link and view the table of contents and such, but not the actual chapters or statues.

    It made good sense from the installer's point of view. if he starts the exhaust out of the pack with the double walled PL pipe, and then fits it with an adapter to 6" single walled; just like out of the back of a wood stove.

    Anyways. I won't be going with that installer - sigh - I'd rather have a safe install vs. a cheap one. And the installer really did a good job at explaining himself when I pressed for how they could do that. (the fact that there are no combustibles with in 18" of the pipe convinced me)

    All this stuff going on is making me second guess my idea of going with a Harman 38P
  9. stoveguy2esw

    stoveguy2esw Minister of Fire

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    nothing wrong with the p-38 , its a decent pellet unit. and would serve you well, provided it was installed correctly and maintained reasonably.
  10. ducker

    ducker Feeling the Heat

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    ok... here's the final word I got from another installer.. they CAN use single wall piping, after they clear the back hopper, yes the pellets might be a conbustable inside a box, but they want to use insulated pipe past the back. After they clear the back, and get far enough above the hopper so it can open properly, they'll then use single wall pipe, if I want (ie. the preexisting perhaps) but it tends to look rather crappy.

    I liked what he had to say, and in the end I went with this installer.
  11. jtp10181

    jtp10181 Minister of Fire

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    No matter what any idiot installer says you have to use all type L or PL venting for a pellet stove/insert. The only single wall pellet pipe I have ever seen is a flexible liner which must be installed into an existing chimney.
  12. stoveguy2esw

    stoveguy2esw Minister of Fire

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    im with Jtp on this one. the only rated pipe allowed with a direct vent pellet unit im aware of is type L or type PL pellet vent pipe. single wall black stove pipe is not rated for pellet direct vent units.
  13. webbie

    webbie Seasoned Moderator Staff Member

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    I think it is pretty much Pellet vent......or, in some rare cases, single wall stainless steel. Way back when, I can admit to perhaps using a little single wall stainless when I was lining a chimney and then had just a short way to go to the stove. Also, we used to do so with fireplace linings, although that may have changed now??

    In any case, any thought of using black pipe or 6" is completely off-the-wall.

    Maybe I missed something....where is the pipe going after that?

    Oh, turning on the wayback machine again - I seem to remember Harman had something in their manuals about using the small ss pipe and then placing 6" pipe around it in a decorative manner....again, in the past.

    Bottom line - in no case would it EVER be OK to use single wall black pipe from the rear of the unit, and even stainless is suspect. The vent on a pellet stove is pretty tight - what they call positive pressure....meaning that air is blowing into it under pressure. This is different than a woodstove where the air is being pulled from the top (negative pressure). Any leaks in a positive pressure system will spill flue gases into the living area! And black pipe certainly is a tight systems....let alone it will probably rot quite quickly given the low stack temps and condensation.
  14. ducker

    ducker Feeling the Heat

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    that black pipe after they clear the hopper would be then going in to the chimney. Your comment about the positive pressure really rings true. I'm not planning on having them do any single wall pipe anywhere. After clearing the hopper or any place. I'll go with the stock double lined, so that it provides the best possible seal.

    Thanks for all the feedback guys!

    -Mike
  15. TRAINGUY

    TRAINGUY New Member

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    I just ordered an Englander pellet insert stove. I plan on installing it myself. In the installation information on their website they show what looks like a flex pipe going from the back of the stove and up the chimney just past the damper. Is this correct or do I have to extend it to the top of the chimney? Also how do you run the air intake to the back of the stove without interfering with the draft? It obviously has to come down the chimney ( I have plenty of room in the 10" flue) since the insert stove is sealed to the face of the fireplace.

    I have installed lots of things including wood stoves over the years but never a pellet stove and never in highly regulated Massachusetts. I appreciate any assistance anyone can give me. Thank you.
  16. Xena

    Xena Minister of Fire

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    Trainguy you should start your own thread in order
    to get the most exposure regarding your questions.

    Seems many newbs on here don't know how to start
    their own topic so if that applies to you, go up to the
    right hand corner of the page and click "new topic"
    and voila! G'luck!
  17. stoveguy2esw

    stoveguy2esw Minister of Fire

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    that installation is a bit different. the direct dump method is only used when outside air is pulled from through the back of the fireplace (check diagram on page 9 of the manual) http://www.englanderstoves.com/manuals/25-PI.pdf
    if pulling outside air through the flue it should be a full liner. personally i prefer the full liner anyway , especially with the size of flue you have. direct dump installs may not even be allowed in mass as tight as they are on regulations they may require a full liner anyway.
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