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Venting over deck

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by zinfendel, Dec 7, 2012.

  1. zinfendel

    zinfendel New Member

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    I am considering buying a Harman Advance and have been pouring over the installation manual. Ideally I want a simple horizontal "stub" vent. Just outside of the place where I want to put my stove is a deck that is maybe 6" lower than the house floor. I understand all of the proximity to windows, grade, soffits, etc. But what I haven't found is min height over a combustible (I assume it is considered that) surface.

    We use the deck in frequently, and I thought I would just take off the pipe on the outside and cap it in the summer anyway.

    I plan on contacting my town inspector (we live an a very small town) and have it inspected etc. as required. But I will do the installation myself.

    Ideas/comments? I would run a snorkel up if I have to but wonder about soffit clearances then.

    JH

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  2. Harvey Schneider

    Harvey Schneider Minister of Fire

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    Things to be cognizant of:
    First, the vent has to be above anticipated snow level. If it isn't you may have difficulty starting the stove. The combustion blower moves a fair amount of air, but doesn't handle much back pressure. If it can't move air you can't ignite the pellets.
    Second. I believe that somewhere in your installation instructions it will say something about the vent cap being at least 12 or 15 inches from any adjacent combustible surfaces.
    Third, the vent cap should be above the air intake (quadrafire reccomends 60" for the Mt Vernon) to prevent a smoke-back
    Fourth, If you don't have a vertical section you may get a smoke-back if there is a power failure
  3. Snowy Rivers

    Snowy Rivers Minister of Fire

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    I can't speak for your local inspector, but your termination will have to be at least 18 inches over the deck.
    You may want to consider a 3-4 foot riser pipe inside behind the stove and then out the wall.

    I have had to get creative on my installs and dealing with a deck can be problematic at best.

    Dropping a vent right out on the deck is not gonna fly though.

    I will venture that you are going to have to use an inside pipe that's tall enough to allow someone to walk under the vent and not hit their head on it.
    This will allow you to leave the pipe out about 18 inches past the siding.
    Also you will have a natural draft too.

    Do speak with your local inspector before you start cutting holes.

    Keep us in the loop
    Ms Snowy
  4. zinfendel

    zinfendel New Member

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    Thanks for the tips. I am going to look at a Harman Advance tomorrow and will probably buy it. I am looking for vent kits now, but want to do things right form the start (before cutting holes). An inside rise then out can work, but my soffit outside, over the deck is relatively low, only about 7' above the inside floor height. So the horizontal exit of the vent would be relatively close to the underside of the soffit.

    So does the vertical section need to extend out beyond the soffit?

    Above the stove, the ceiling is vaulted, 45 degree pitch, so going all vertical through the roof does need seem appealing.

    I will contact my local inspector, but I live in a very small town of just 3100 people, so this might be interesting.....

    Thanks

    John H
  5. zinfendel

    zinfendel New Member

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    Well, I bought the stove, and called the town offices. After a bit of runaround I found that the town building inspector was the one to approve. I have worked with him before, he's a good guy. On the phone, he simply said "fill out the building permit form, drop it off at town hall with $50, install the stove and call me when you are done so I can come and look at it."

    And he did know that I was going to install it myself.

    So my thought is this (comments welcome).

    I fill out the form, print a copy of the Harman install manual, diagram the venting I expect to use, and take a pic and print it of the place where I want to install the stove before I start work, and submit all of that with the permit app so he can look it over before he comes out.

    I'll assume that he will only be looking for adherence to the Harman install manual for clearances, etc. They are pretty specific in there.

    I will run the vent straight out of the back of the stove, elbow and rise outside over the deck. I bought this stove because depth is an issue, and if I elbow and rise inside the house, it will cost me 8-9" of depth. Rear clearance minimum is only 1" with this stove. No hearth, the floor is all ceramic tile.

    Outside, my soffit is ventilated and only 7' off the deck surface. Also, there is a door on one side, and window on the other of where the stove will go. So my plan is to rise to just under the soffit, then elbow and horizontal to a termination about 12" beyond the soffit/gutter. This would be needed to keep me 18" away from the soffit and 48" from the door/window. Will be ugly as hell, but it is the only way I can see to meet the specs.

    My concern (as someone mentioned above) is that he will have an issue with the obstruction on the deck. We don't use it much at all in the summer. The termination will probably be about 6' over the deck surface. The Harman manual requires 7" clearance under a vent over a sidewalk or driveway, but says nothing about over decks.

    One other thought is to put wooded planter, perhaps screwed to the deck, under the vent to keep someone from walking under it (I'm 6' 3" !)
  6. moey

    moey Minister of Fire

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    I would interpret the 7" clearance as a clearance over a surface that may have something on top of it snow debris, tree branch etc. A deck would fall under the same category.
  7. zinfendel

    zinfendel New Member

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    My bad, Harman manual requires 7 feet of clearance under a vent that is over a sidewalk or driveway,
  8. Lousyweather

    Lousyweather Guest

    yup, but yours is neither...its a deck. maybe use an outside air kit to mitigate the 4' clearnace from an operable door or window to 18". Your dealer should sell them as well...$165-$180 or so.
    lvsb likes this.
  9. zinfendel

    zinfendel New Member

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    Yep, that is exactly what I have concluded, thinking this over further. With an OAK, I can easily fit within the specs, including under a ventilated soffit (18") and I won't have to run the snorkle vent up as high.

    Another Q, and reason why I couldn't just cut 2.5" holes in my thimble faces, outside of the ring protecting the flue pass through, and run the OAK hose through that way? Every OAK thimble I have seen a pic of does just that and I think I should have no issues with space for it through the wall. I have already bought a vent kit which includes the thimble.
  10. zinfendel

    zinfendel New Member

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    Ok, I'm into it now.... hole in the wall. 2 questions.

    1. Is it OK for insulation to be in contact with the outer case of the wall thimble. I have seen many responses yes, and a few no.

    2. Is it necessary to run horizontal 2x6 (in my 2x6 walls) above and below the thimble? I see it shown in some diagrams, but it does not say in the text that it is required in the stove, or vent kit manuals?

    All post some pics of the install this weekend.

    Thanks
  11. Harvey Schneider

    Harvey Schneider Minister of Fire

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    You need a fire block above the thimble.
  12. zinfendel

    zinfendel New Member

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    Can you point me to a code or manufacturers statement that a firestop above the thimble is required? I can't find any, and have found many installation manuals that state that firestop is needed for vertical penetrations but that "the through wall acts as a firestop". In any case I will ask my inspector, but I'd like to find some documentation to point him to if possible.


    Another Q: I want my stove to be close the wall, and the vertical above the T outside to be 3-4" from the wall using standard brackets. Using a 12" section and the appliance adapter at the stove as the first horizontal will push either the stove out away from the wall and/or the pipe stack away outside.

    Can I just connect/clamp/screw the 12" section right to the flange on the stove and lose the added length of the adapter? The only difference I can see in the ends of each is that the 12" section has the pressings for the interlock. I could flatten those with pliers.

    If not any other suggestions to shorten this length? I bought an "adjustable" section at HD tonight, but it seems to only be able to extend another 12" section.



    Thanks...
  13. Lousyweather

    Lousyweather Guest

    if its the Harman thimble, the thimble doesnt require a fireblock above, and yes, the insulation can come into contact with the outer wall of the thimble.....

    you should be using a stove adapter to make the connection to the stove. Im guessing you are using Simpson pipe (from Home depot)? Not my fave, but they make sections as small as 6". Dont modify the pipe.
  14. TheMightyMoe

    TheMightyMoe Minister of Fire

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    You want the best advice you will ever get ?

    Take a picture of install location, and venting location, with marks for where you plan to put what.

    We will set you straight.

    It's very hard to transfer text to pictures =)

    I don't think anyone here will suggest modifying the pipe in anyway... Double pipe has a specific purpose.
  15. zinfendel

    zinfendel New Member

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    Well here are some pics. Venting at this spot was quite a challenge, as you can see. I had to deal with a baseboard heater which I partially cut away, baseboard and nearby studs in the walls. Luckily, an outlet was already in the perfect place. I had to drill out the rivets in the inside collar of the thimble to be able to slip the face of it behind the baseboard heater pipe. I just used sheet metal screws there when I put it back together. I cut some 1/2" plywood buffers for behind the corners of the face so it would not collapse in. I used drywall anchors in the wallboard.

    [​IMG]

    [​IMG]
    [​IMG][​IMG][​IMG]

    So I didn't modify anything on the vent hardware. I used the appliance adapter, and a 12" section to outside, the cleanout T there and it all worked out dimensionally. The stove is out away from the wall maybe 1.5" farther than ideal, but it all lines up perfectly. I'll post pics of the outside later.

    This stove is AMAZING!! We have an open concept contemporary home, this stove sits on the far side of a large family room with a vaulted ceiling that reaches 22ft at the peak. About 1800 s.f. on the first floor. Adjacent to it is the kitchen with 2 large open entries. I ran the stove last night at 6 out of 7 for about 3 hours, and it brought up the temp from 66 to 70 degrees.... over the entire house. It was 31 degrees outside when I started, and 25F after 3 hours. I knew a pellet stove would work well here, this house is very open. Heat flows up to the second floor via the stairs and an open terrace in the upstairs hallway. Very warm up there too.


    Tonight I ran it in room temp mode with the probe on the wall above the stove. It brought it up to 69 degrees and shut down. My wife, who was VERY skeptical of an "ugly" stove in the family room loves it, and loves being warm in the house.

    So the last big challenge before I call the inspector over to approve and close the permit, is the OAK setup. I will have to do this not because of vacuum build up, but because it will drop my door and window proximity to vent termination from 48" to 18". I hope to be able to hole saw a 2.5" in hole in the thimble face just above and to the side of the 6" insert cylinder and run a steel flex line outside for that. Pics to follow.

    Does my fire look OK? Not sure what "good" is. I have the pellet feed set on 4. The ash (Green Supreme pellets) seems dark and "crumbly" (if that makes any sense) as apposed to a fine, sand like ash.

    Thanks for all the tips and help.....
  16. Lousyweather

    Lousyweather Guest

    I dont know how much of a stuickler your inspector is, but modifying the thimble like you mention technically should get you failed on the inspection- youre modifying a UL listed system, thereby invalidating the UL listing completely. If you insist on using that type of thimble, use a separate intake line.....second hole in wall. I mentioned above an intake thimble......its made by Harman, all one piece, one hole. What you propose MIGHT work, but in the world of combustibles, carbon monoxide, your largest investment, and your loved ones, why take the risk. Do it right. What you propose isnt "right".
  17. zinfendel

    zinfendel New Member

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    Well I only thought about drilling the thimble face for the OAK because Harman sells one just like that. But making another hole for the intake air is not a problem. I'll look for the intake air thimble, thanks for the tip.
  18. TheMightyMoe

    TheMightyMoe Minister of Fire

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    Many people use aluminum dryer/automotive vents for their air intake line, some pellet stoves even suggest it (The Wiseway for example)

    You didn't show any pictures of your exterior venting.

    I can see your deck through the venting, if your inspector decides its a combustible, then your SOL. Decks are considered a flammable usually, not a combustible.

    On a good note, the manual isn't clear about installing venting above a wood deck, so the inspector might let it fly.
  19. zinfendel

    zinfendel New Member

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    "I can see your deck through the venting, if your inspector decides its a combustible, then your SOL. Decks are considered a flammable usually, not a combustible."

    Currently I have a cleanout T outside the wall and two 12" vertical sections before 90 degree elbow and termination vent. This places the vent a bit over 3 feet over the deck. Would this be an issue even if the deck is considered combustible? I thought 18" from combustibles was sufficient.

    I'll post pics of the vent later, still not sure how high to go. Since it is on the deck, I'd prefer it to be "torso high" as to make it more obvious and less likely to be walked into. Also, it keeps it farther away from the vented soffit above. I have 2 more 12" sections that came with the vent kit that I can use if necessary.

    I ordered some 2 3/8" flex steel pipe from McMaster for the intake air. It's max bend radius is 8" however, and with the stove about 4" from the wall, my options for wall penetration/exit will be limited. I have not found a source for a more flexible 2 3/8" pipe. I am finding that Harman makes it difficult to buy their venting products on line.
  20. zinfendel

    zinfendel New Member

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    Happy to call it official today, as our building inspector came by and signed off on the install.

    I ended up cutting into the thimble fascias and running a 2" flex pipe through it (from another Duravent OAK that I bought). I used a muffler adapter piece I got at autozone to adapt the intake port on the stove to the hose. It is basically the same thing as this Duravent product.

    http://www.ventingpipe.com/duravent-4pvp-wti3-3-flex-diameter-wall-thimble-air-intake-kit/p1792302
    [​IMG]

    The thin wire out of the faceplate is my thermostat sensor, runs up the inside of the wall and comes out just above a home theater speaker.

    [​IMG]

    The thimble fascia is not crooked, there is some Tyvek across the top of it. I have to tidy up the siding, put J channel around it etc., ... but will wait for warmer weather for that!!

    [​IMG]

    You can see the OAK port in the thimble fascia. I am going to make a miniature dryer vent kind of hood for it out aluminum flashing. Not the prettiest thing to have on the deck, but I'll trade it for the warmer house in the winter.
  21. mikkeeh

    mikkeeh Burning Hunk

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    Your air intake is fairly close to the deck. Not sure where you live....but be aware of drifting snow!

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