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  1. #1
    Join Date
    Nov 2012
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    1

    Cool How to control the fresh air coming into the boiler room.

    We have installed a new boiler in our mountain home that does NOT use outside air for combustion. Our heater contractor tells us that to meet code we must drop a 6" pipe into the boiler room that is open to the outside (no damper). We are told that there are no damper kits that are made to control the flow of air so the pipe would be wide open to the outside all of the time. Our home is at 8500~ above sea level and we are very concerned that there will be a huge amount of cold air pouring into our home during the winter with just a open pipe to the outside and no damper. We need help. There has got to be a better way to get the needed fresh air into the boiler room and still control the flow of bitterly cold air. Help

  2. #2
    Join Date
    Sep 2012
    Location
    Boston
    Posts
    820

    Default Re: How to control the fresh air coming into the boiler room.

    that makes no sense to me what-so-ever. if your furnace has a separate sources for combustion and exhaust then you do not need to ventilate the furnace room. i assume you have a double lined chimney vent/exhaust pipe. call the manufacturer directly and ask them.

  3. #3
    Join Date
    Aug 2008
    Posts
    66

    Default Re: How to control the fresh air coming into the boiler room.

    What make & model do you have for the new furnace/boiler & is it gas-fired or oil-fired??? And do you have a copy of the installation manual that always comes with the new unit????

    Air is just as essential for good combustion as the fuel used & is always spelled out in the mfgr's installation manual with appropriate diagrams; the IM can be downloaded from the internet if you don't have one, it's a very handy & important document that has a wealth of info on the workings of your furnace/boiler.

    The need for combustion air is compounded for those living in higher altitudes---at 8,000' the available air is thinner so the adjustment is usually an additional 3.5% for every 1000' above sea level.

    There are 3 types of draft systems based on the efficiency rating of the heating equipment:

    1) Natural Draft for units that are approx 80% or less efficient.
    2) Direct Vent for more efficient equipment
    3) Sealed Combustion for high efficiency heating units.

    The first classification uses no sealed power ducting, but simply uses the available air in the boiler room and sucking supply air using duct tubing from a vented attic, crawl space, or outside vents; the latter 2 use power venting & sealed ducting to suck in outside combustion air & to vent the combustion products of the boiler/furnace out of the house, usually with a negative draft system by having the power draft near the outside exhaust vent to maintain negative pressure along the tubing to prevent combustion product leaks into the home.

    Any powered venting will be more expensive due to the powered equipment used, but allows more efficient heating equipment to be used in the home for better fuel savings, does a better job of sucking in good combustion air, expelling dangerous combustion produces, & keeping the boiler room warm---because of the health concerns connected to inappropriate boiler/furnace ventings, it is the discretion of the licensed installer that matters in these installations; (think of the home umpire at a baseball game); it doesn't mean the installer is right, or that there aren't any acceptable alternatives to his plan, you can always get a 2nd or 3rd opinion, but these installers are following code regulations & stand to lose their license if a carbon monoxide accident causes death or injury.

    With venting issues, there is usually another way to "skin the cat" that will keep the boiler room warm, & still be in compliance with applicable codes.

    National & local codes spell out air & venting requirements for central heating systems, & have to be followed for the safety & health of the home's occupants; applicable code requirements for the specific heating apparatus are spelled out in the Furnace/Boiler's Installation Manual given to the homeowner, & are based on (internet) NFPA 54, NFPA 31, CSD-1, BOCA, SBCCI.

    http://www.nationalboard.org/index.a...eID=164&ID=191
    http://energy.gov/energysaver/articl...es-and-boilers
    Last edited by dodsworth; 11-16-2012 at 12:01 PM.

  4. #4
    Join Date
    Mar 2010
    Location
    Canada
    Posts
    86

    Default Re: How to control the fresh air coming into the boiler room.

    Quote Originally Posted by CUBeatty View Post
    We have installed a new boiler in our mountain home that does NOT use outside air for combustion. Our heater contractor tells us that to meet code we must drop a 6" pipe into the boiler room that is open to the outside (no damper). We are told that there are no damper kits that are made to control the flow of air so the pipe would be wide open to the outside all of the time. Our home is at 8500~ above sea level and we are very concerned that there will be a huge amount of cold air pouring into our home during the winter with just a open pipe to the outside and no damper. We need help. There has got to be a better way to get the needed fresh air into the boiler room and still control the flow of bitterly cold air. Help
    There is.
    Many years ago, in the prairie region of Canada, enforcement began of the gas code provision that you have to supply fresh air to a furnace or boiler for combustion. This separate source of air became necessary for combustion units and their chimneys because we began making energy efficient houses that didn't supply enough air for the furnace/boiler burner through cold air drafts.
    For most sized units found in residential homes, a 6 inch line vented directly to the outdoors is required.
    The most common methods are using insulated flex ducting attached to a metal screened duct hood (outside) with the open end terminating 12 inches off the floor. a modification is to still have the same configuration, except to have the open end splill into a 5 gallon pail. A more sophisticated modeified version is to have the flex duct come down then backup , forming a P trap. Problem is while this satisfy the gas code for combustion supply air it does freezing cold air into the home.
    Now if you have a modern sealed combustion unit, you don't need this because the heating unit has its own air supply provided directly to the burner.

    Several years back,an inventor in Alberta began marketing the Hoyme damper. It is a motorized damper that is tied into the thermostat of the furnace or boiler. When the thermostat calls for heat, the damper opens. In fact, the furnace can't even go on unless it is open. When the furnace goes off, it closes. In addition it is set up so that the fail safe position is open, maybe making a cold basement but assuring that the chimney won't be backdrafting dangerous gasses into the house. It is the only combustion air damper that I am aware of that is approved by the gas code.
    If you install this damper, your furnace/chimney will have the combustion air it needs to work properly and you won't have a freezing cold basement because of that large open fresh air duct.

    Here is the link to the product.
    http://www.hoyme.com/index.php?optio...d=48&Itemid=57

  5. #5
    Join Date
    Aug 2007
    Location
    Maryland
    Posts
    1,160

    Default Re: How to control the fresh air coming into the boiler room.

    motor operated dampers tied into boilers are common with commercial equipment. Since the previous posters is familiar with a residential unit, I would look for it

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