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  1. #53
    Quote Originally Posted by key1cc View Post
    Sorry to jump in but that may be bad news for me. My trane xv95 is 100k btu input 95k btu output and my blower speed is set at ~1200 giving a static pressure of 0.65.
    The temp rise spec range is 35 - 65.
    My unit is set to only operate in stage 1. Am i looking at an issue other than paying too much for a stage 1 furnace?
    Key
    Key,

    Are you set up for the 1200 cfm on first stage or second?

  2. #54
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    The install instructions should have a temp rise chart to use.

    Or you need a volumeter, or a pitot tube to do a velocity check.
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  3. #55
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    Quote Originally Posted by mark johnson View Post
    Key,

    Are you set up for the 1200 cfm on first stage or second?
    Currently it is locked into 1st stage using the Tstat and the dips are set on medium to deliver ~1200 CFM.
    According to my Service facts document, if I allow it to go to 2nd stage with the dips set on medium the call would be for ~1690 CFM at 0.5 TESP (and ~1400 CFM at static 0f 0.9...essentially identical to what Beenthere predicted.)

    The weather has not yet been cold enough to test if this set up of operating in 1 stage only will be adequate to keep the house warm. I suspect it will be fine as I was easily able to cool the house in 95+ degree days with adjusted airflow of 1200-1300 CFMs.

    Key1
    In the land of the blind.....the man with one eye is king....

  4. #56
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    Quote Originally Posted by beenthere View Post
    The install instructions should have a temp rise chart to use.

    Or you need a volumeter, or a pitot tube to do a velocity check.
    My install instructions have the CFM vs. Temp rise data but for my 100kbtu unit the data starts above where I am (1300-2400 CFM).....I suspect it is stage 2 data only and I operate in stage 1.

    I estimate my CFMs based on the static pressure.
    Is the Pitot tube method more accurate?

    Key1
    In the land of the blind.....the man with one eye is king....

  5. #57
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    Can be more misleadings.

    You need about a 6' run of duct with no ells or transitions for it to be accurate.
    And its not just one reading, but a transverse of the duct.
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  6. #58
    Quote Originally Posted by beenthere View Post
    The install instructions should have a temp rise chart to use.

    Or you need a volumeter, or a pitot tube to do a velocity check.
    I see the cfm/temp rise chart in the instructions, so that sounds like a good way to measure cfm indirectly. I'll give it a shot, because I am curious what the actual delivered cfm is.

    Quote Originally Posted by key1cc View Post
    I estimate my CFMs based on the static pressure.
    That's intriguing, I didn't know there was a way to do that. How do you do that?

  7. #59
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    Quote Originally Posted by mark johnson View Post



    That's intriguing, I didn't know there was a way to do that. How do you do that?
    It takes a little algerbra.
    But first you have to establish an actual CFM at a static pressure.
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  8. #60
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    Quote Originally Posted by mark johnson View Post
    I see the cfm/temp rise chart in the instructions, so that sounds like a good way to measure cfm indirectly. I'll give it a shot, because I am curious what the actual delivered cfm is.



    That's intriguing, I didn't know there was a way to do that. How do you do that?
    The service facts document in the installation guide has a table of airflow (CFMs) versus power (in watts) versus external static presure..............for any given dip switch setting (low, medium, high, etc). It also provides the temp rise data at that specific static presure.....sooooo if you know your external static pressure and you know your airflow settings (dip swith settings). The table tells you your corresponding airflow, temp rise, and wattage draw for stage 1 and stage 2.
    As Beenthere pointed out, it is tricky to check the actual airflow but the wattage draw and temp rise can easily be verified with the proper instruments and know-how. For now, I just except the data as accurate.

    Key1
    In the land of the blind.....the man with one eye is king....

  9. #61
    Quote Originally Posted by beenthere View Post
    It takes a little algerbra.
    But first you have to establish an actual CFM at a static pressure.
    I got an "A" in Algebra, so I'm game . As for the second part, do you mean to measure the static at a lower cfm to get a reference point, and then go from there?

    I don't have cfm vs static chart in my instructions/product guide like Key does, so I need to know the trick . So if you can educate me on this, I'm all ears!

  10. #62
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    I have the formula in a spread sheet.

    Give me the CFM and the base line static, and I'll enter them, and tell you what the static would be at what ever CFM you need to know.
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  11. #63
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    Quote Originally Posted by mark johnson View Post
    I don't have cfm vs static chart in my instructions/product guide like Key does, so I need to know the trick . So if you can educate me on this, I'm all ears!
    The data is typically in the installers guide (not owners guide) and your installer may not have left it with you. You can always call and ask for a copy. I believe you have a goodman system per one of your earlier threads.

    Attached is a spec sheet from the Goodman website. It may have the data you are looking for. Not sure if it is your model but the site has similar sheets for other models. Link is below.

    Key1

    http://www.goodmanmfg.com/Home/Produ...5/Default.aspx
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  12. #64
    Quote Originally Posted by beenthere View Post
    I have the formula in a spread sheet.

    Give me the CFM and the base line static, and I'll enter them, and tell you what the static would be at what ever CFM you need to know.
    Thanks beenthere!

    OK, at 1200 cfm setting, I get about 0.40" static. I assume that this is a good reference point, since the static is low. Here is what I get at higher speed settings - would be curious to see how this lines up with your spreadsheet:

    cfm setting static
    1600 0.90"
    1800 0.95"
    2000 1.05"

    So what actual cfm do you think I'm getting at the higher flows?

  13. #65
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    Quote Originally Posted by mark johnson View Post
    Thanks beenthere!

    OK, at 1200 cfm setting, I get about 0.40" static. I assume that this is a good reference point, since the static is low. Here is what I get at higher speed settings - would be curious to see how this lines up with your spreadsheet:

    cfm setting static
    1600 0.90"
    1800 0.95"
    2000 1.05"

    So what actual cfm do you think I'm getting at the higher flows?
    With 1200 CFM at .4" as base line.

    1600-.71"
    1800-.90"
    2000-1.11"
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