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  1. #14
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    Sep 2002
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    Northeast Ohio
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    There's your tag line Josh, "Changing the HVAC industry for the better, one system at a time!"
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  2. #15
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    Oct 2003
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    Washington
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    Quote Originally Posted by craig1 View Post
    I like that hold-down on the condenser. never seen something like that before.
    Just a 3' piece of rebar hammered into the ground, held with a grounding clamp that has a drive fastened through it and screwed to the unit. The inspectors love it around here.

  3. #16
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    Oct 2003
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    Washington
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    Quote Originally Posted by chuckcrj View Post
    Good work.

    Did you do a combustion analysis? If not they may not save much over their old one. Most new furnaces come severely underfired.

    And BTW where are the Bryant Evolution systems we were promised pics of? LOL

    I don't agree with your first statement. We don't do combustion analysis until we come back for our 1st maintenance. Upon initial startup we do set the gas pressures properly and, of course, make sure system static is operating within manufacturers' spec. I have never in my 16 years had a new 90+ furnace with poor combustion.


    To answer the Bryant question, they have been a tough sell against the Goodman systems because we get crappy pricing.

  4. #17
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    Feb 2010
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    Quote Originally Posted by seatonheating View Post
    I have never in my 16 years had a new 90+ furnace with poor combustion.

    Then you simply don't know what the numbers mean when you do stick the CA probe in the flue pipe. Or else you aren't checking them with a CA. Your customers could be saving a LOT more money with thier new systems.

    If the O2 is above 9% it has poor combustion. 80% or more new 90+ furnaces will be 10% O2 and higher when set up according to manu specs.

    Enough hijacking, I won't beat it anymore. Unless we start a thread in the pro section.

  5. #18
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    Quote Originally Posted by chuckcrj View Post
    Then you simply don't know what the numbers mean when you do stick the CA probe in the flue pipe. Or else you aren't checking them with a CA. Your customers could be saving a LOT more money with thier new systems.

    If the O2 is above 9% it has poor combustion. 80% or more new 90+ furnaces will be 10% O2 and higher when set up according to manu specs.

    Enough hijacking, I won't beat it anymore. Unless we start a thread in the pro section.

    Other than setting up gas pressures and making sure the venting is proper what are you going to do to fix it? Install a carburetor onto the brand new furnace? Get real.


    And I know how to do a proper combustion analysis, don't insult me.

  6. #19
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    Quote Originally Posted by seatonheating View Post
    Other than setting up gas pressures and making sure the venting is proper what are you going to do to fix it? Install a carburetor onto the brand new furnace? Get real.
    The answer is adjust gas up or air down, quite simple really.



    Quote Originally Posted by seatonheating View Post
    And I know how to do a proper combustion analysis, don't insult me.
    If you haven't found any 90+ with poor combustion in 16 years then no you don't. Sorry if you take it as an insult, its simply a fact.

  7. #20
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    Oct 2003
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    Quote Originally Posted by chuckcrj View Post
    The answer is adjust gas up or air down, quite simple really.





    If you haven't found any 90+ with poor combustion in 16 years then no you don't. Sorry if you take it as an insult, its simply a fact.


    I'm sticking to 3.5 I/WC thank you very much!


    And your second statement is false. Don't tell me what I've found.

  8. #21
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    Dec 2005
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    Cincinnati, Oh
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    Quote Originally Posted by chuckcrj View Post
    The answer is adjust gas up or air down, quite simple really.
    Are you saying you set gas pressure outside of the manufact. REQUIRED specs, as daily practice?
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  9. #22
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    Quote Originally Posted by chuckcrj View Post
    The answer is adjust gas up or air down, quite simple really..


    Sorry, gotta throw the bullsh!t card on this one.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  10. #23
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    Quote Originally Posted by heaterman View Post
    Sorry, gotta throw the bullsh!t card on this one.

    Yep, that is why he is getting my blood up.

  11. #24
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    Feb 2010
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    OK since you guys want to discuss it here......

    Raising manifold pressure is not the only way to follow the instructions in the owners manual which state you must correct the input btu if it is not correct. The following quotes are from the IOM of a common furnace.(Trane TUX1 single stage condensing furnace) Right after it tells you how to clock the meter is the following;

    6. Multiply the final figure by the heating value of the
    gas obtained from the utility company and compare
    to the nameplate rating. This must not exceed the
    nameplate rating.
    Gas Valve Adjustment
    Changes can be made by adjusting the manifold pressure
    (See Table 12), or changing orifices (orifice
    change may not always be required).
    Table 11 lists the main burner orifices used with the furnace.
    If a change of orifices is required to correct the
    furnace input rating refer to Table 14.
    Input rate changes can be made by adjusting the manifold
    pressure (min 3.0 - max 3.7 in. W.C. - Natural Gas)
    or changing orifices (orifice change may not always be
    required). If the desired input rate can not be achieved
    with a change in manifold pressure, then the orifices
    must be changed.
    Clocking the meter does not take into account the btu content of the gas. Using a combustion analyzer, manometer, and temp probe, is more accurate and much faster than clocking the meter. And it gets your actual input btu to the manufacturer rating on the nameplate.

    The above furnace comes with #45 burner orifices. Lets use a 100k btu unit for example that has 5 burners. If you look at an orifice chart it will tell you that you get 17,072 BTU at 3.5" per burner.

    17,072 X 5 burners gives us an input of 85,360 BTU. WAIT A MINUTE! I thought we had a 100,000 btu input furnace?? Apparently not!

    So you have a much cooler flame due to the O2 content being high, and the flame is much smaller and therefore farther away from the HX, with the result of being much less than 90% efficient! In fact doing the sensible heat calculation (delta T X CFM X 1.08) in the above furnace will often give you 60,000 to 65,000 BTU actually being delivered to the space! I have mesured it, more than once. 85kbtu in and 65kbtu out equals 76% efficiency!!

    But the AFUE sticker says 92%......

    Its not just Trane either, take a look at what size orifices the next furnace you install has and do the math.

  12. #25
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    Quote Originally Posted by chuckcrj View Post
    OK since you guys want to discuss it here......

    Raising manifold pressure is not the only way to follow the instructions in the owners manual which state you must correct the input btu if it is not correct. The following quotes are from the IOM of a common furnace.(Trane TUX1 single stage condensing furnace) Right after it tells you how to clock the meter is the following;







    Clocking the meter does not take into account the btu content of the gas. Using a combustion analyzer, manometer, and temp probe, is more accurate and much faster than clocking the meter. And it gets your actual input btu to the manufacturer rating on the nameplate.

    The above furnace comes with #45 burner orifices. Lets use a 100k btu unit for example that has 5 burners. If you look at an orifice chart it will tell you that you get 17,072 BTU at 3.5" per burner.

    17,072 X 5 burners gives us an input of 85,360 BTU. WAIT A MINUTE! I thought we had a 100,000 btu input furnace?? Apparently not!

    So you have a much cooler flame due to the O2 content being high, and the flame is much smaller and therefore farther away from the HX, with the result of being much less than 90% efficient! In fact doing the sensible heat calculation (delta T X CFM X 1.08) in the above furnace will often give you 60,000 to 65,000 BTU actually being delivered to the space! I have mesured it, more than once. 85kbtu in and 65kbtu out equals 76% efficiency!!

    But the AFUE sticker says 92%......

    Its not just Trane either, take a look at what size orifices the next furnace you install has and do the math.



    I'm not buying that!!! As long as I do my homework and have proper airflow across my heat exchanger with proper statics then I will have the proper temp-rise, hence the properly delivered BTU's. As a by-product, the combustion efficiency of the furnace will more than fall within what is observed during laboratory testing.

    What you are saying is outright misleading and false and should not be posted in an open forum.

  13. #26
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    Quote Originally Posted by seatonheating View Post
    I'm not buying that!!! As long as I do my homework and have proper airflow across my heat exchanger with proper statics then I will have the proper temp-rise, hence the properly delivered BTU's. As a by-product, the combustion efficiency of the furnace will more than fall within what is observed during laboratory testing.

    What you are saying is outright misleading and false and should not be posted in an open forum.
    I thought you were more intelligent than this.

    You didn't post the size of that furnace but lets say its a GCVC90905 90kbtu input.

    It has #43 orifices, 4 of them. At 3.5" you have 20,111 btu per burner for a total of 80,444 btu.

    Thats IF you have the perfect 1,000 BTU per cubic foot.

    So you sold them a 90K unit that only has an 80K input. Hope you didn't cut the manual J sizing too close.

    If you put in the 70 then it actuall only has a 60,333 input.

    Edit; I went back to the OP and saw that you did install a 70k.

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