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Outside Air Kits, Do you recommend them?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by MountainStoveGuy, Jul 16, 2006.

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  1. elkimmeg

    elkimmeg Guest

    http://www.mass.gov/bbrs/780CMR_Ch3620.pdf

    3610.6.4Air for combustion and ventilation:
    Solid fuel-burning appliances shall be installed in a
    location and manner to assure satisfactory
    combustion of fuel, proper chimney draft and
    maintenance of safe operating temperatures.
    Combustion air may be obtained from interior
    spaces when the interior space containing the
    appliance has a volume, in cubic feet equal to one
    twentieth
    (1/20) of the output Btu rating of all
    fuel-burning appliances in the space. When
    buildings are so tight as to preclude adequate
    infiltration, provisions shall be made to introduce
    outside air for combustion and ventilation

    2003 NFPA 211

    12.3 Air for Combustion and Ventilation.
    12.3.1 Solid fuel-burning appliances shall be installed in a location and manner so as to provide ventilation and combustion air supply to allow proper combustion of fuel, chimney draft, and maintenance of safe temperatures.
    12.3.2 Where buildings are so tight that normal infiltration does not provide the necessary air, outside air shall be introduc

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  2. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Thanks for the post Elk. I now know I don't need outside air. You could fling a cat through any one of the air leaks in this place.
  3. elkimmeg

    elkimmeg Guest

    BB I'm sitting on the fence on this issue. One question asked was why do stove manufactures provide optional outside air kit provisions?. Many said it was to open their markets to the state of Wa. There is another answer to be code compliant in tight homes, and stoves installed in areas with insufficient combustion air. Which also explains why OA is required in mobile homes there is not enough air vollume to support proper combustion. Plus not all rooms qualify to supply combustion air Bath rooms do not qualify. If I dig deep enough in the fire codes, I sure there is language that rules out bedrooms. Even common sense tells one not to oxygen deplete bedrooms.
  4. Roospike

    Roospike New Member

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    I know it states that most gas heaters are not to be used in bedrooms , lack of oxygen . I was going to call Pacific Energy about the Outside air issues but just never got around to it yet , maybe Monday . I did ask about the outside air kits from my local dealer when i bought my stove last october , but got a deer in the headlight look from them, like i did with most of my questions that were not "standard questions".
  5. begreen

    begreen Mooderator Staff Member

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    I've been looking at many stove manuals today for clearances to combustibles. While in there, I looked into outside air information. Jotul had the most complete explanation. Here is what they have for the Oslo:

    Outside air may be required if:
    1. The Jøtul F 500 does not “draw” steadily, smoke rollout occurs,
    fuel burns poorly, or back-drafts occur whether or not there
    is combustion present.
    2. Existing fuel-fired equipment in the house, such as fireplaces
    or other heating appliances, smell, do not operate properly,
    suffer smoke roll - out when opened, or back-draft whether
    or not there is combustion present.
    3. Opening a window slightly on a calm (windless) day alleviates
    any of the above symptoms.
    4. The house is equipped with a well-sealed vapor barrier and
    tight fitting windows and/or has any powered devices that
    exhaust house air.
    5. There is excessive condensation on the windows in the
    winter.
    6. A ventilation system is installed in the house.

    If these or other indications suggest that infiltration air is
    inadequate, additional combustion air should be provided from
    the outdoors.
  6. Roospike

    Roospike New Member

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    Makes sence . How many time has one heard to "open a window" for better draft . Not that i have to but have heard it many times over the years . mostly to get the fire rolling/started. good input B.G.
  7. suematteva

    suematteva New Member

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    Elk or Others,

    Does it say anything about OA and basement installations? A snorkel type setup was not recommended.

    I spoke with two people from Hearthstone about OAK and am not sold on adding the thing on..Fully described the stove location and the type of burning, quality of wood and size, running temps of the stove, cresote level and house age, usual wind direction. Age of house...This debate is very install specific.

    My friend with a Jotul, basement install. Swears by it. He burned two years with out it. Added on loves it. When cold 10 f the intake pipe will have rime ice for two ft in..I would have to say it it really pulling air.

    When manufacturers test stoves for burning performance in a lab how do they do it?.Is an outside type air kit used..Every home is obviously different yet they would have to use average home scenario.
  8. scfa99

    scfa99 New Member

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    Just re-read my Quadrafire 7100 manual.

    Page 21, warning box "IMPORTANT! outside air knob on front of fireplace must be in the open to operate firepace properly".

    "Outside air is required to minimize the effects of negative pressure within the structure."

    Page 9, "outside air is required for combustion".

    So as a consumer, these statements imply that i HAVE to use it. very confusing.
  9. MountainStoveGuy

    MountainStoveGuy New Member

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    Thata correct, you have to hook some built in fireplaces to outside air. Since its a sealed front unit and its built in the wall that makes sense. You absolutly HAVE to use it. That unit has a second combustion air port designed to pull combustion air from another part of the house to help circulate inside air.
  10. elkimmeg

    elkimmeg Guest

    Elk or Others,

    Does it say anything about OA and basement installations? A snorkel type setup was not recommended.

    I spoke with two people from Hearthstone about OAK and am not sold on adding the thing on..Fully described the stove location and the type of burning, quality of wood and size, running temps of the stove, cresote level and house age, usual wind direction. Age of house...This debate is very install specific.

    My friend with a Jotul, basement install. Swears by it. He burned two years with out it. Added on loves it. When cold 10 f the intake pipe will have rime ice for two ft in..I would have to say it it really pulling air.

    When manufacturers test stoves for burning performance in a lab how do they do it?.Is an outside type air kit used..Every home is obviously different yet they would have to use average home scenario.[/quote]

    Snorkel code calls fro an exit location 1' above average snow fall But nobody can tell what the average dept of snowfall in in all locations. Many are snorkeling the inlets and outlets locations to raise them to add extra margine of safety. There are issues, that add to the total length of the run and additional resistance or friction.

    Your friend has a differnt location different stove and should insulate that air supply if he is getting ice in there

    I know all the EPA test results I have reviewed they are in open areas. I supose to spec them they have to test them.
  11. suematteva

    suematteva New Member

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    Snorkel code calls fro an exit location 1' above average snow fall But nobody can tell what the average dept of snowfall in in all locations. Many are snorkeling the inlets and outlets locations to raise them to add extra margine of safety. There are issues, that add to the total length of the run and additional resistance or friction.

    Your friend has a differnt location different stove and should insulate that air supply if he is getting ice in there

    I know all the EPA test results I have reviewed they are in open areas. I supose to spec them they have to test them.[/quote]

    Thanks Elk.

    When I referred to "snorkel" meant more a basement installation. Snorkel (my analogy) meaning pulling the air from up above the foundation wall...Understand about the min 1 ft above average snowfall....In an above thread i think the term was low oxygne area (or something like it)..Would this include a basement..trying to understand why they do not recommend OAK in basement. thanks matt..am going to get my stove manual..
  12. velvetfoot

    velvetfoot Minister of Fire

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    I just read that for one particular burnham boiler cold air can result in flue temps that might be below condensation point causing possible corrosion. (This is research for my possible purchase of an OAK for my oil burner).

    Wouldn't cold air be denser and result in better combustion?
  13. elkimmeg

    elkimmeg Guest

    There is language that allows adding the basment location for combustion make up air Most basements have competing appliances and it is not good to interupt what is already working. The definition of outside air id air taken beyond the exterior of the home.. I think it best to continue additional air to the outside, a sealed passage can travel threw the basement. Colder air also contains more oxygen and is better for combustion. It is also denser and more is available for combustion. IF an insert is spected for only outside air and placed in a firebox Then it is not going to work Particularly if there are no provisions for room air to enter the combustion chamber. This debate can go on and on but all agree there are circumstances where outside air is the only solution.
  14. tradergordo

    tradergordo Minister of Fire

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    "When buildings are so tight as to preclude adequate infiltration, provisions shall be made to introduce outside air for combustion and ventilation"

    So does this rule out direct connection outside air kits (because they do not provide ventilation which appears to be a requirement of this code)?

    "Even common sense tells one not to oxygen deplete bedrooms"

    The assumption (and I've seen it several times now from OA proponents) seems to be that a stove using room air depletes the room of oxygen. Based on what I've read, this is rarely the case (which is probably another reason why all the stove manufacturers techs have been saying the OAK's are unnecessary). Only in the event that a stove depressurizes the room would you have oxygen depletion - in all other cases, you would actually be INCREASING oxygen levels in a bedroom (or any room with people in it) by using room air for your stove. Why? Because the stove draws in fresh air and exhausts stale air (air you've already depleted of oxygen by breathing it in then out).

    I think a lot of people assume that modern high efficiency air tight wood stoves use a lot of air like an open fireplace. The code you quoted seems to assume the same use of air per BTU from every appliance - not sure that is a reasonable assumption:

    "Combustion air may be obtained from interior spaces when the interior space containing the
    appliance has a volume, in cubic feet equal to one twentieth (1/20) of the output Btu rating of all
    fuel-burning appliances in the space."

    Also not sure what "in the space" means, in the same room?
    So if my math is right, you can only use room air with a 50,000 BTU stove when it is in a "space" equivalent to 17.7 feet x 17.7 feet x 8 foot ceiling (and no other fuel burning appliance is in the same "space").

    "When buildings are so tight as to preclude adequate infiltration, provisions shall be made to introduce outside air for combustion and ventilation "

    How do you measure infiltration for adequacy? Do you actually run the appliance while observing an air pressure meter or is it just based on the equation above?



  15. elkimmeg

    elkimmeg Guest

    Alll good valid questions I'm on myMac now but I willl supply the actual description of open air space the short version id any ajoining rooms that do not have a door that can be closed or it adequate sized grills are space in the walls so that air can communicate between rooms Louver doors allow air thansmission as well Forget the 1/20 code also establishes for every 1000 BTU of an appliance output 50 cubic ft of free air is needed to support proper combustion. This becomes a huge problem, when people finish off basements. and partition off the burner and hot water heaters in small confined spaces.

    If what you say is true then please educate all about the oxygen Ventless gass heaters have oxygen depletion sensors that shut down the units when the oxygen levels drop to approaching unsafe levels.. I have wittnessed then shut down with test equipment measuring the oxygen levels..

    There are companies that test green homes that presurize homes and measure infiltration or escaping If anyone is interested I will try to post a copy of how it is done and the testing results. This one builder certifies his homes to be energy star compliant.

    Condensttion of cold air by burnham I doubt that Cold dry air has less moisture so what's to condensate? If they were bringin warm moist air in a cool envoirment I can see how that could condensate but not the opposite way around. There is another way to bring in outside air called air in a can that is not directly connected to the burner head or combustion chamber

    later tonight I will cut and paste the acctual code about open space when I'm on my laptop. This is a good discussion

    You did not click on the link at the top of the codes it is the entire chapter concerning combustion air

    http://www.mass.gov/bbrs/780CMR_Ch3620.pdf
  16. tradergordo

    tradergordo Minister of Fire

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    From Outdoor combustion air in the Canadian national building code

    Made mandatory in 1990, removed entirely in 1995
    The 1990 National Building Code (NBC) of Canada had mandatory requirements for outdoor air supplies for fireplaces, but, when the findings of Canada Mortgage and Housing Corporation (CMHC) research on outdoor air supplies were tabled during the revision cycle leading to the 1995 edition, the requirements were removed.

    Here is some background on the evolution of outdoor air supplies in the NBC.

    The 1990 NBC contained the following Article (clause): "9.22.1.4 Combustion Air. Fireplaces, including factory-built fireplaces, shall have a supply of combustion air. (See Appendix A)"

    Appendix A-9.22.1.4. read in part: "The intent of this Article is to allow the fireplace to be operated without affecting, or being affected by, other appliances or exhaust equipment. For this to occur, the fireplace must be provided with a supply of combustion air dedicated to the fireplace only; an opening to the exterior should be provided at or near the fireplace opening."

    The Article went on to require outdoor air for factory-built fireplaces in accordance with the manufacturer's instructions and gave a series of prescriptive requirements for outdoor air supplies for site-built masonry fireplaces.

    In the proposed revisions sent out for public comment in August 1993, it was proposed to delete Appendix note A-9.22.1.4. with the following reason given: "Combustion air supplies as currently prescribed are generally ineffective. The requirement to provide combustion air is being deleted from CAN/CSA A-405, Design and Construction of Masonry Chimneys and Fireplaces and from the Code."

    The '95 NBC contains the following: "9.22.1.4. Combustion Air. Where a supply of combustion air is provided directly to the fire chamber of a fireplace, including a factory-built fireplace, the installation shall comply with the "Outdoor Air Supply" requirements provided by CAN/CSA A-405, Design and Construction of Masonry Chimneys and Fireplaces." This is the only reference to combustion air for fireplaces.

    The supply of outdoor air was made non-mandatory and this wording was included because the CMHC research that showed outdoor air supplies to be ineffective, also showed that direct-to-combustion chamber supplies could be hazardous because of the potential for wind-induced reverse flow of combustion gases through the supply duct. The A-405 requirements proposed ways to provide outdoor air safely if you choose to supply it.

    Like most building codes in North America, the NBC included outdoor combustion air requirements for combustion equipment on the assumption that it was a good strategy to reduce spillage susceptibility. Unfortunately the assumption was acted upon before any research had been done to explore how outdoor air supplies actually behave.

    The research reports that influenced the Standing Committee of Part 9 of the NBC are:

    1) Fireplace Air Requirements, ORTECH for Canada Mortgage and Housing Corporation, 1989

    2) The Effects of Glass Doors on Masonry Fireplace Spillage and Surface Temperatures, Virginia Polytechnic Institute for Canada Mortgage and Housing Corporation, 1994

    Copies of these reports are available from the CMHC information centre at (613) 748-2367.

    Although the two studies were conducted by two labs with different set-ups, different protocols and different appliance types (1. factory-built, 2. masonry), they arrived at the same conclusion: The susceptibility to combustion spillage due to room depressurization is not affected in a predictable way by the presence or absence of air supplied from outdoors, whether supplied to the combustion chamber or indirectly through a supply duct terminating near the fireplace.

    In both studies the reference room depressurization at which spillage was induced was 10 Pa. In 'Fireplace Air Requirements', none of the five tested fireplaces spilled at 5 Pa depressurization despite the fact that all were very different in their configurations and features, although all did have glass doors. The tests at the two depressurization levels were done with and without outdoor combustion air supplies.

    Once the research findings were in and analyzed, the underlying physical process became clear: That is, air flows to a zone of lower pressure through any available opening, regardless of our wishful thinking. In retrospect, this principle appears rather obvious, although for most of us it was not until revealed in the lab.
    ...
  17. tradergordo

    tradergordo Minister of Fire

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    You are forgetting that an airtight wood stove drafts. The draft is a critical component of the system. In fact I would argue that most draft problems are the result of improper installation (and not due to using room air). In my opinion it would be better to fix a bad installation rather than just slapping on an outside air kit. The draft of the stove is what pulls fresh air into the house as stale air is exhausted from the house. A ventless gass heater obviously cannot do this. So yes, ventless devices, even candles, can deplete a room of oxygen.


    I'm interested.
  18. elkimmeg

    elkimmeg Guest

    I think Canada has a colder climate than most of USA. Colder air has different oxygen and density levels at colder temp Testing for atmosphere conditions in mid Ontario is, not the same as in Virginia. agree? A good part of Canada is also close to or above the Arctic circle, none of the lower 48 is, in-fact at least a thousand of miles away. Canada also requires liners in Every masonry setup. They also have greater distances to combustibles, than we do, from 36" to 48". Are you saying we should enforce Canadian code? Almost every masonry chimney application would be illegal here. Almost every clearance to combustibles would be illegal. The reason aditional metal liners are required, and not here, is the colder climate conditions.. So at what point do we use their a codes, and can they even apply here to our warmer climates. It obvious the Canada recognised theire climate to require different code. Could it be outside air colder more density exhibits different characteristics the warmer more moist air here? Please quote reference to studies here. The Virgina Tech study was a Canadian study but where here or Canada?. As a code official what do you want me to do? choose to ignore code and enforce other codes? Enforce what I choose. I enforce what is written. Now if you want to introduce your finding, I would be more than willing to help you go threw the code revision process. I have read these studies before and they present valid points. None of these studies went far enough to have multi openings on different pressure sides of the homes as I suggested. These studies were doom to failure because wind does not blow in the same direction at all times. One outlet is not enough. and all your fact finding is proving this. Find me facts where multi openings are failing.

    tradergordo We agree on many common issues , like correcting poorly installed stoves/ venting systems. Remember the min Verticle height provides of min satisfactory opperation, not optium. Higher chimneys draft better, interior chimneys draft better.

    What about location factor of the chimney requiring outside air? exposed chimniys need more assistance and draft poorer than interior chimneys EVEn the NFPA reconsise this fact the way ther revised the 2003 cros-sectional codes
  19. KP Matt

    KP Matt New Member

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    Elk, I'm surprised at you - Vogelzang = bad, Ventless gas heater = acceptable? (goodhumoured ribbing)

    I'd venture a guess that the primary reason ventless appliances have automatic switches is not because they deplete oxygen levels but because, by definition, they pump carbon monoxide into the air. Humans can survive reasonably low oxygen levels (ever been in the mountains) but carbon monoxide?


    For the CMHC studies they are here:

    http://www.cmhc.ca/publications/en/rh-pr/tech/95-202.pdf

    http://www.woodheat.org/outdoorair/outdoorcmhc.htm (actually just excerpts - the full report is available elsewhere online)

    And for good measure, a less than glowing piece on unvented gas fireplaces: http://www.cmhc.ca/publications/en/rh-pr/tech/97-116-e.pdf

    What I'm wondering is, if modern stoves in modern houses NEED an OAK (and I will assume that stove efficiency gains have outpaced house insulation improvements), how could open fireplaces have EVER worked at all, given the fact that they use SO MUCH air?
  20. stuart

    stuart New Member

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    This brings me to a question this past winter i had my stove up on high,as i was sitting i can hear the room expand or contract with the warmth, realy warm, could i need fresh air input? If i need to install fresh air pipe ,1 1/5 round pipe can i run it out the side of the house about 10 ft from stove to get fresh air from the breez way??
  21. elkimmeg

    elkimmeg Guest

    This being a familly forum, I can not truely express what I think about Ventless heaters. I can say you will not find one in my house.

    In time the Vogelzang and scandia pieces of ------------ stoves will re appear in post. ITs been almost two months since I comented about them.

    There are situations /conditions where OAK are a solution. I think of them as suplemental air unless, the entire stove is designed and recieves all combustion air from outside, then it is spected and mandatory to be installed per specs.

    In the office I will copy a report certifying a home to energy star standards in the mean time I am sure a web search has that info , for those who can not wait. I have seen them put a rubber membrane blatter in the door way with a blower to suck out the air. I have seen magnetic rubber sheets blocking HVAC vents testing leakage. I have seen balance reports of duct work for every room
    In order to qualify for energy star homes the HVAC duct work can only loose 12% in heat transmission, the normal is up to 35%
    I have worked with the builder and HVAC contractor and come up with solutions that achieved this 12%. First we designed the placements and duct run outs to be the shortest possible. Second to reduce friction, all bends 90 degrees or more are made with smooth galvanized elbows, This reduces friction and maxumises vollume bending a flexible duct oblongs the diameters and increases friction and restricts air flow. All joints are sealed with duct mastic, including metal elbows. All take offs are gasketed and duct sealed.
    All flexible ducts are R6.0 not 4.2. Plemums and trunk lines are R6.0, about 2" of foil wrap fiber glass insulation. The furnaces and exchangers are caulkked or masticed preventing more leaks. High low returns with dampers distrobute heat or Ac more evenly.
    Really its too bad code does not govern placement. or I could really enforce more energy saving effeciencies. I do have the power of suggestion and the ability to educate.

    The international codes does require an outside air feed for new construction in fireplaces. IT's up to the user /owner, whether he uses it
  22. tradergordo

    tradergordo Minister of Fire

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    I wrote to John Gulland hoping he might share some more thoughts with us on this debate. Doesn't look like he has much to add to what has already been written. I believe John also has in the past been a contributor to code changes related to this subject (in Canada). I think his point makes a lot of sense in that the burden of evidence should be on the outside air proponents to do some actual research instead of just talking about anecdotal evidence. The reason so many jurisdictions dropped outside air requirements from code is because of the research already done in this area. This research is now pretty old, and stoves are more efficient today. You would think the state of Washington, which requires OAKs could fund a study, or perhaps an insurance company as was done in Canada.

    Anyway, this is what John G. had to say via email (bold was added by me):

  23. KP Matt

    KP Matt New Member

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  24. webbie

    webbie Seasoned Moderator Staff Member

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    John is the God of house pressurization and has written books and worked for the Canadian Government and other such orgs in relation to this. You can rest assurred that his conclusions and opinions are as close as you will get to the facts.

    In other words, it's like asking Elk about nail spacing........if he doesn't know, then no one does!

    Given this long thread, are there any budding authors among us who want to try and distill it all into fact and give us a new wiki article? I'm pushing the wiki, because combined knowledge, edited by folks who like to write, is the cat's meow on subjects like this.....

    Please....pretty please......

    http://www.hearthwiki.com
  25. KP Matt

    KP Matt New Member

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    Shouldn't the Wiki have (1) a "Pro-Outside Air" and (2) an "Anti-Outside Air" entry? As well as something describing (3) the range of Outside Air Kits available, and (4)a review of the history and current state of code, industry acceptance, insurance and any related information pertaining to the requirement to/not use outside Air?

    That breaks it into more manageable pieces, and should preclude problems of bias.
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