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i.d. boiler vent part

k1c | Posted in Energy, Heating & Insulation on September 17, 2010 12:04pm

Sorry no picture and my description may not be good.  If problem, will have to learn how to post photos.  Anyway, I am looking at this part along the mid span of vent pipe.  Again, sorry but I did not know that venting may be different for oil or gas.  This part attaches over the cut out on the bottom of the 8″ vent pipe.  It is oval and about 12″ long and maybe half that wide.  It is open.  Inspectapedia lists such things as barometric  damper or draft regulator, but this part is open and hangs on the bottom part of the pipe.  If this part and the pipe is turned up, it looks like a submarine and its tower.  It looks as if it is supposed to supply extra air, but it worries me that there is such large opening in the pipe.  This is, by the way, my father in laws house and they lived with it for decades.  I just happened to notice it and asking here because I don’t know anything about it.  I don’t want to mention it just yet to them out of not worrying them unncecessarily.

As far as I know, they haven’t complained of smell or anything.  Thank you in advance.

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  1. Shacko | Sep 17, 2010 02:53pm | #1

    Barometric Damper

    . >>> It looks as if it is supposed to supply extra air,<<<

    That's exactly what it supposed to do, with the appliance running it will open and close depending on the air up the flue.

    They do get out ouf adjustment, if it hasn't been checked all those years it would be a good idea to have it checked before the heat season. You can't smell carbon monoxide which will kill you!!

    1. k1c | Sep 17, 2010 04:02pm | #2

      Thank you for the reply.  I saw the pictures of regulators and they are always on the side (that is, opening is on the side) with a door.  This part is on the bottom of the vent pipe and is oval.  If this had some sort of damping door, it is gone now.  Would you know the name of this part, so I can get one if it needs to be replaced?  Again, thank you.

      1. Shacko | Sep 17, 2010 05:07pm | #3

        Barometric Damper

        http://www.thefind.com/appliances/info-barometric-damper

        Here's a link of different dampers, the way they are hooked up varies with the install, they don't have to be oval. It's almost inpossible to find a part for them if thats what you have in mind, don't forget if you replace it, it has to be adjusted, system should be checked for excess carbon monoxide.

        1. k1c | Sep 17, 2010 08:27pm | #5

          vent

          Thank you and that site is handy.  I don't know if this part I am looking for was a damper.  It is oval and not made for a logical door like a round duct dampers.  I am going to take a photo of it and will try to post it here.  Thank you.

          1. DanH | Sep 17, 2010 08:40pm | #7

            It's been awhile since I've seen one of these, but my recollection is that the device was a piece of round duct teed off of the main flue  The teed-off piece could be pointing either horizontally or generally downward, depending on design.  Inside this piece of duct was an oval disk, with a horizontal shaft running off-center across the width of disk and supporting it by passing through holes in sides of the duct, and with a rod with a balance weight running off perpendicular to the disk.  The device was adjusted by sliding the weight along the rod.

            I've never read/heard instructions on how to adjust the units, but I would suspect that they would be adjusted such that the disk would be almost closed when the furnace is not operating, but would open up (allowing air to be drawn into the flue) when the furnace fires.

  2. DanH | Sep 17, 2010 06:48pm | #4

    What you're describing was fairly normal on the old oil systems I used to see -- a bit less common on gas (which tended to have a different but equivalent scheme).

    The main thing, if the damper is undamaged and no one has mucked with the setting, is to make sure that it swings freely.  If it doesn't swing free, is damaged, or has been mucked with, it should be checked by a pro.  Of course, an oil system should be checked by a pro every year anyway -- or at least every two years.  Oil systems require much more maintenance than gas to keep operating well.

    1. k1c | Sep 17, 2010 08:30pm | #6

      vent

      Thank you for reply.  The original boiler may have been oil then changed later.  I am going to ask them and get more info...about the kind of fuel and such.  Thank you.

    2. Tim | Sep 28, 2010 01:43pm | #12

      FOS

      as usual. These devices are very common in gas fired boilers as well as oil. They are adjusted to maintain specified draft at full fire.

      1. DanH | Sep 28, 2010 09:22pm | #14

        Well, maybe gas-fired boilers, but I've never seen one on a GFA unit.  (And where I've lived gas-fired boilers were a rarity -- it was either oil-fired boilers or GFA.)

        1. rich1 | Sep 29, 2010 08:40pm | #15

          I may be FOS

          but I'm willing to bet it ain't a baro damper.    Either one of you ever see one that mounts on the BOTTOM of a vent????

          Probably a draft regulator.  No damper involved, just some plates that were adjusted to regulate the draft.

          To the OP, if you are really concerned by now, you will need an old-timer or a good boiler guy who really knows boilers to tell you what it is. 

          Here is a quick and dirty test.  Fire the boiler and wait a few minutes for the chimney to warm up.  Then place your hand under the opening. You should feel no heat spilling from the bottom of the opening. 

          FWIW, I work on boilers. 

          1. DanH | Sep 29, 2010 08:41pm | #16

            You may be correct, but it's impossible to say with any certainty given that the OP isn't giving much feedback.  I think the best advice is still the same -- don't touch it and call a pro.

          2. Tim | Sep 30, 2010 09:09am | #17

            You may be

            but the comment was not directed at you, but rather someone that is without a doubt, FOS.

            I agree the device is a draft regulator, hence the comment, "adjusted to maintain specified draft".

            They let plumbers work on boilers in the great white north? Eh? Better than HA computer programmers.

          3. rich1 | Sep 30, 2010 09:39am | #18

            I know the direction, but their ain't no smilies here.

            In my part of the north, only plumbers and fitters can get a gas ticket.  And plumbing, refregeration, electrical and sheetmetal are compulsory/protected trades.    No such thing as an HVAC ticket up here in the great white north.

  3. rdesigns | Sep 17, 2010 09:23pm | #8

    If the boiler was changed from oil to gas, then it's likely that the barometric damper is not needed at all--definitely not if the change to gas was made after l991--that's when higher efficiency requirements mandated by the fed. gov't led to manufacturers abandoning draft hoods on furnaces. Draft hoods did the same thing as the barometric damper did for oil furnaces--they allowed dilution air to mix into the flue and assist the exhaust flow. Gas furnaces with gravity vents now make use of a combustion-assist fan that mixes the dilution air, but does not actually pressurize the vent.

    The best and safest thing is bring in a pro and have him decide--you can do this without alarming your elderly in-laws by explaining that a furnace of that vintage is overdue for a routine checkup.

    1. DanH | Sep 17, 2010 10:08pm | #9

      I certainly wouldn't attempt to close the vent or do anything to it other than a light dusting/lubrication without the advice of a pro.  Messing with it could be dangerous.

      1. DanH | Sep 17, 2010 10:12pm | #10

        And if this is an old oil furnace converted to gas, replacing the furnace is probably in order.  The old unit is likely running about 50% efficiency, and a new unit (depending on where in the country this is and how large/drafty the house) could potentially pay for itself in 5 years or less, in addition to being safer and freeing up a lot of space in the utility area.

  4. Clewless1 | Sep 18, 2010 08:55am | #11

    You're right ... difficult w/out a pic to help us. It does sound a little like a barometric damper. Did you observe it when the boiler was running?

  5. Tim | Sep 28, 2010 01:56pm | #13

    Please don't take this

    the wrong way, but what do you expect to accomplish?

    All of the "advice" offered up here is from people who are not professional boiler mechanics. I am not a boiler mechanic but I know exactly what is is, how it works, why its there and how it is supposed to be adjusted and maintained and I would hire a professional, if it were mine. The best advice has been repeated, "Hire a professional" and I'll add "Don' t touch it!".

    Pardon the tone, but improper adjustment could kill people.

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