Gas Fireplace Shuts Off

Discussion in 'Home Repair' started by Houston, Dec 19, 2005.

  1. Houston

    Houston Guest

    I asked this question a couple of months ago but I'd like to restate my
    problem and make sure I get it right. Installed unvented gas logs two
    years ago. The line for it originates between the gas furnace and gas
    water heater, about a 25 foot run with I think 5/8" copper, but maybe
    1/2". I'm not at that house right now. Shut-off valve to the right of
    the fireplace. The OEM gas line running directly into the unit is
    small, so it seems 1/2 to 5/8 should be enough to feed it. But when the
    furnace kicks in, or the water heater, the fire gets sucked away and we
    have to relight the pilot also. It seems the easiest solution would be
    some sort of inline valve that prevents that backflow when another
    appliance kicks in, but I'm not aware of such a thing? Do I simply need
    still larger tube to the fireplace? Anybody experienced this? Thanks
    for any suggestions.
     
    Houston, Dec 19, 2005
    #1
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  2. Houston

    Oscar_Lives Guest

    "Houston" <> wrote in message
    news:...
    >I asked this question a couple of months ago but I'd like to restate my
    > problem and make sure I get it right. Installed unvented gas logs two
    > years ago. The line for it originates between the gas furnace and gas
    > water heater, about a 25 foot run with I think 5/8" copper, but maybe
    > 1/2". I'm not at that house right now. Shut-off valve to the right of
    > the fireplace. The OEM gas line running directly into the unit is
    > small, so it seems 1/2 to 5/8 should be enough to feed it. But when the
    > furnace kicks in, or the water heater, the fire gets sucked away and we
    > have to relight the pilot also. It seems the easiest solution would be
    > some sort of inline valve that prevents that backflow when another
    > appliance kicks in, but I'm not aware of such a thing? Do I simply need
    > still larger tube to the fireplace? Anybody experienced this? Thanks
    > for any suggestions.
    >


    What's the gas line pressure?
     
    Oscar_Lives, Dec 19, 2005
    #2
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  3. Houston

    Houston Guest

    I think I was told it was about 4 lbs. That sound in the ballpark?
     
    Houston, Dec 19, 2005
    #3
  4. Houston

    Oscar_Lives Guest

    "Houston" <> wrote in message
    news:...
    >I think I was told it was about 4 lbs. That sound in the ballpark?
    >


    I haven's seen a fireplace in a ballpark.

    It sounds to me like you need a professional technician to diagnose and
    resolve your problem(s).

    You shouldn't be messing with stuff you don't understand. You might blow
    yourself up.
     
    Oscar_Lives, Dec 19, 2005
    #4
  5. Houston

    Houston Guest

    So memory fails regarding pressure. The pressure was tested and deemed
    adequate before the install.
     
    Houston, Dec 19, 2005
    #5
  6. Houston

    mm Guest

    On 18 Dec 2005 17:06:10 -0800, "Houston" <> wrote:

    >I asked this question a couple of months ago but I'd like to restate my
    >problem and make sure I get it right. Installed unvented gas logs two
    >years ago. The line for it originates between the gas furnace and gas
    >water heater, about a 25 foot run with I think 5/8" copper, but maybe
    >1/2". I'm not at that house right now. Shut-off valve to the right of
    >the fireplace. The OEM gas line running directly into the unit is
    >small, so it seems 1/2 to 5/8 should be enough to feed it. But when the
    >furnace kicks in, or the water heater, the fire gets sucked away and we
    >have to relight the pilot also. It seems the easiest solution would be
    >some sort of inline valve that prevents that backflow when another
    >appliance kicks in, but I'm not aware of such a thing? Do I simply need
    >still larger tube to the fireplace? Anybody experienced this? Thanks
    >for any suggestions.


    Again, I have no experience other than cooking with a gas stove, 20
    years ago, but I'm trying to think like a stream of gas. Indeed, i AM
    a stream of gas. (jokes expected, but please, no really vulgar ones.)

    Although it looks like the flame is being sucked in, I suspect that it
    would look that way even if the gas pressure dropped a lot. it
    wouldn't be necessary for gas to flow the opposite direction, so I
    don't think that a backflow preventer (if there is such a thing) would
    help.

    Think about it. If one stops the gas pressure, the flame which was
    burning gas an inch from the gas jet will burn that gas up, and then
    it will start burning the gas that is closer to the jet until it burns
    all the way down to the jet (where iiuc it won't burn what hasn't come
    out yet because there is no air to burn it with, or the heat is
    dissipated by the pipe, and it isn't hot enough, or something.)

    This is going to look like the flame and the gas it is burning is
    sucked in, but until someone says that is possible, I'm thinking my
    description of what happens would look like what you see.


    Remove NOPSAM to email me. Please let
    me know if you have posted also.
     
    mm, Dec 19, 2005
    #6
  7. Houston

    Houston Guest

    There are several CO detectors installed in nearby locations and we
    haven't had a problem there, but the vent suggestion may make sense. I
    couldn't guarantee that my folks open a window (or open it enough) each
    time they use the fireplace. My concerns was -and is - that by tapping
    into the gas line between the furnace and the water heater, I've
    lowered the usable pressure on the long run to the fireplace. It's got
    just enough to burn normally until there is the slightest draw from
    another source. I assume the furnace is the biggest draw, and by
    tapping after it, I lose the pressure when it comes on for that initial
    flare burn. At least that's been my working hypothesis. But I see that
    a lack of vent (oxygen) might have the same effect. I guess "sucked"
    was the wrong terminology. It just goes out. Once the furnace has
    ignited I can relight the pilot and logs. I'm being very cautious
    indeed, would like to be able to finish what I started and getting
    working consistently right. Thanks
     
    Houston, Dec 19, 2005
    #7
  8. Houston

    CBHVAC Guest

    "Houston" <> wrote in message
    news:...
    > So memory fails regarding pressure. The pressure was tested and deemed
    > adequate before the install.
    >


    Real simple, pressure has little to do with it, since the appliance will
    have, or BETTER have a regulator in it that drops it way below 4lbs.

    You cant just go slapping gas lines in on existing, since most of the time,
    the builder, or installer will size the line for the volume needed for what
    is on the line, period.
    Gas lines must be sized for the demand, and it sure sounds like yours are
    not.
    Volume...not pressure is what matters most. Pressure is handled by the
    regulators, volume is handled by the size of the lines.
    Most, are undersized in the futile attempt to save a few bux.
     
    CBHVAC, Dec 20, 2005
    #8
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