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  1. #40
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,123
    Quote Originally Posted by hvacvegas View Post
    interesting how you left out:

    "ALWAYS CONNECT A MONOMETER TO THE OUTLET TAP AT THE GAS
    VALVE BEFORE ADJUSTING THE PRESSURE REGULATOR. IN NO CASE
    SHOULD THE FINAL MANIFOLD PRESSURE VARY MORE THAN PLUS OR
    MINUS .3 INCHES WATER COLUMN FROM 3.5 INCHES WATER COLUMN
    FOR NATURAL GAS OR 10 INCHES WATER COLUMN FOR PROPANE GAS."

    which is immediately after it.
    Sorry I left it out, it doesn't take away from the fact that they want their furnaces started up properly and verified.

    If it means adjusting the manifold pressure or resizing the orifices, it needs to be done to correct an underfired furnace.

  2. #41
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,123
    Quote Originally Posted by hvacvegas View Post
    If it's at 76% efficiency, and the heat isn't being absorbed, then how is the flue gas below the dew point, and condensating?
    The heat was'nt absorbed because it wasn't being produced in the first place. The gas was being burned but it was burning at a cool temp.

    When you have 6% O2 the flame temp is 2800.
    When burning at 12% O2 the flame temp is 2000.

    60% or more of the heat transfer in any combustion appliance comes from radiant heat off the flame itself. Which flame in is going to radiate more heat to the HX? The 2800 flame or the 2000 flame?

    You can try it sometime, just restrict the air going to a burner to bring your O2 down. You will see your temp rise across the heat exchanger increase which means more btus are being produced. You didn't add any gas but you are getting more btus out of that same amount of gas!!

  3. #42
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    Quote Originally Posted by chuckcrj View Post
    The heat was'nt absorbed because it wasn't being produced in the first place. The gas was being burned but it was burning at a cool temp.

    When you have 6% O2 the flame temp is 2800.
    When burning at 12% O2 the flame temp is 2000.

    60% or more of the heat transfer in any combustion appliance comes from radiant heat off the flame itself. Which flame in is going to radiate more heat to the HX? The 2800 flame or the 2000 flame?

    You can try it sometime, just restrict the air going to a burner to bring your O2 down. You will see your temp rise across the heat exchanger increase which means more btus are being produced. You didn't add any gas but you are getting more btus out of that same amount of gas!!

    You are acting like this O2 in can be adjusted on a brand new furnace.

    Ok, next install I'm going to install mesh over half of my intake pipe..


    I get what you are saying, but it isn't practical. Time for you to bow out gracefully.

  4. #43
    Join Date
    Aug 2003
    Location
    Central Kentucky
    Posts
    6,247
    Quote Originally Posted by seatonheating View Post
    You are acting like this O2 in can be adjusted on a brand new furnace.

    Ok, next install I'm going to install mesh over half of my intake pipe..


    I get what you are saying, but it isn't practical. Time for you to bow out gracefully.
    You might want to consider what he's saying instead of dismissing it.

    O2 can be adjusted on a 90% 2 pipe furnace if you know what you're doing and you never have to touch the fuel to do it.
    Have you set up a Google alert for Carbon Monoxide yet?
    Click here to find out how.

  5. #44
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,123
    Quote Originally Posted by seatonheating View Post
    You are acting like this O2 in can be adjusted on a brand new furnace.

    Ok, next install I'm going to install mesh over half of my intake pipe..


    I get what you are saying, but it isn't practical. Time for you to bow out gracefully.
    I adjust the O2 on every startup and tuneup I do. New, old, natural draft, induced draft, condensing furnace, boiler, etc.... Very practical as it saves the ho money and makes their epuipment last longer.

    I would never put a mesh screen in the intake. Their are other ways to adjust air.

    As for bowing out I certainly can if its getting too uncomfortable for you.

  6. #45
    Join Date
    Aug 2003
    Location
    Central Kentucky
    Posts
    6,247
    Quote Originally Posted by hvacvegas View Post
    If it's at 76% efficiency, and the heat isn't being absorbed, then how is the flue gas below the dew point, and condensating?
    One thing to keep in mind is the different types of efficiencies that are out there and how they are defined.

    It looks like Chuck was referring to a furnaces thermal efficiency which is the actual amount of BTUs being delivered from the furnace compared to what it is rated to output.

    There are a lot of times that they don't add up.
    Have you set up a Google alert for Carbon Monoxide yet?
    Click here to find out how.

  7. #46
    Join Date
    Jul 2009
    Location
    st louis mo
    Posts
    334
    the angle of your dangle, is in direct porportion to the heat of your meat, and the mass of your bottom remains at a constant temperature and pressure at all times given the relative humidity, grains of moisture per lb of dry air, and dry bulb, wet bulb is approiate. got it?

  8. #47
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    Quote Originally Posted by chuckcrj View Post
    I adjust the O2 on every startup and tuneup I do. New, old, natural draft, induced draft, condensing furnace, boiler, etc.... Very practical as it saves the ho money and makes their epuipment last longer.

    I would never put a mesh screen in the intake. Their are other ways to adjust air.

    As for bowing out I certainly can if its getting too uncomfortable for you.

    Sure ya do.

  9. #48
    Join Date
    Jun 2008
    Location
    CT
    Posts
    45

    Smile Good man

    Nice job there is alot goin on there i like the flex connecter here we have to hard pipe everything

  10. #49
    Join Date
    Jun 2002
    Location
    Upstate Central NY
    Posts
    590
    So how exactly do you adjust oxygen levels in a 95% furnace? Different restrictor plates in the inducer?

    All of out techs use analyzers and adjust the air for atmoshpheric systems, but i have never heard of adjusting the air on a 95%. Have in extreme cases turned down manifold pressure for correct CO levels, etc.

    This is a very interesting conversation......

  11. #50
    Join Date
    Apr 2010
    Location
    Minnesota
    Posts
    517
    Wow, I guess I'm going to have to change the way I do things. I've been setting them up to 3.5" with the factory orifices for 8 years and now I find out it's wrong?

  12. #51
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    Quote Originally Posted by dunkman View Post
    Wow, I guess I'm going to have to change the way I do things. I've been setting them up to 3.5" with the factory orifices for 8 years and now I find out it's wrong?

    'cause he is a troll and his recommendations are funny. Let's just modify everything!!

    Easy there, this can be a very interesting thread if you let it, instead of the above.
    Tell you what. I'm going home and adjusting the gas pressures in my water heater because my kids take long showers..... Better combustion will equal more hot water, right?
    Last edited by Stamas; 04-05-2011 at 09:04 AM. Reason: Note.

  13. #52
    Join Date
    Sep 2006
    Location
    The depths of hell in PHX AZ
    Posts
    1,140
    Quote Originally Posted by chuckcrj View Post
    The heat was'nt absorbed because it wasn't being produced in the first place. The gas was being burned but it was burning at a cool temp.

    When you have 6% O2 the flame temp is 2800.
    When burning at 12% O2 the flame temp is 2000.

    60% or more of the heat transfer in any combustion appliance comes from radiant heat off the flame itself. Which flame in is going to radiate more heat to the HX? The 2800 flame or the 2000 flame?

    You can try it sometime, just restrict the air going to a burner to bring your O2 down. You will see your temp rise across the heat exchanger increase which means more btus are being produced. You didn't add any gas but you are getting more btus out of that same amount of gas!!
    I would be interested to see just how high your stack temperature shoots up when you do this as well. The proof would be in the combustion efficiency that pops up in your pretty little meter.

    I agree with seaton. Something doesn't add up. And who the hell made that orifice chart? Doesn't look very official to me.

    But this thread will live on I'm sure.
    I will believe that the government is broke when the welfare checks start bouncing!!

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