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  1. #1
    Join Date
    Nov 2012
    Location
    Charlotte, Michigan 48813
    Posts
    125

    ESP: Am I measuring this correctly?

    Upflow furnace, Goodman GMH950453BX.

    I put the probe in the blower compartment to get return static, measured it with no filter and with a six month old MERV 11 installed.

    For supply static, I put the probe near the center, just above the heat exchanger, where I found the highest pressure reading.

    For TESP, I added the return suction with filter to the supply pressure.

    Did I measure it right? (I wonder if the meter changed zero between the 2.5 and 3.0 ton readings, but it always read 0.00 in basement air)

    Do these numbers look OK? (my filter is 20x25x4")
    According to the Goodman airflow chart, I'm getting about 725-730 cfm on the 1.5T setting. (734 at .30 static, 704 at .40)

    Blower tons Return__Return filtered Filter Drop Supply __ TESP
    1.5_______-.11_______-.19_________-.08____.13______.32

    2.0_______-.16_______-.27_________-.11____.18______.45

    2.5_______-.22_______-.35_________-.13____.19______.54

    3.0_______-.23_______-.38_________-.15____.23______.56

  2. #2
    Join Date
    Nov 2012
    Location
    Charlotte, Michigan 48813
    Posts
    125
    The top two blower settings are pretty loud.

    Currently, it's wired for lowest speed at low heat and 2nd lowest speed for high heat.

    If I have a 1.5T heat pump installed, is it possible to run both low heat and heat pump at the low blower setting?
    The matching coil is supposed to add 0.041" dry, 0.071" wet to the ESP at 700 cfm and .052", .089" at 800 cfm.

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,960
    Quote Originally Posted by taxman View Post
    The top two blower settings are pretty loud.

    Currently, it's wired for lowest speed at low heat and 2nd lowest speed for high heat.

    If I have a 1.5T heat pump installed, is it possible to run both low heat and heat pump at the low blower setting?
    The matching coil is supposed to add 0.041" dry, 0.071" wet to the ESP at 700 cfm and .052", .089" at 800 cfm.
    Seems like it should add more ESP than that; but I don't have the figures on that system.

    What tonnage size is the indoor coil?

    Normally, a 2-Ton coil at 700-CFM will have a static pressure drop of .17" to .20"-WC dry ,& .20" to. .23"-WC wet.

    Could you copy what you read & post it here?

    Video checking static ESP | Video 2 checking static ESP

  4. #4
    Join Date
    Nov 2012
    Location
    Charlotte, Michigan 48813
    Posts
    125
    Darrell:
    Link: http://www.goodmanmfg.com/Portals/0/pdf/SS/SS-GCoil.pdf

    On page 8, look up the specs for the 1.5-2 ton 17" wide coil, CAPF1824B6, it's a match for a 1.5 ton 13 Seer.
    The 14" wide version CAPF1824A6, has 3-4x the resistance.

    The match for the 14 Seer is the 2.5 ton CAPF3131B26, which has even less resistance than the 13 Seer coil.

    I got my furnace airflow specs from page 7 of this pdf:
    http://www.goodmanmfg.com/Portals/0/pdf/SS/SS-GMH95.pdf

  5. #5
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,960
    AIRFlOW DATA for CSCF AIR QUANTITY (SCFM) vs. Pressure drop (In. WC)
    CSCF18 24N6D*

    If I have a 1.5T heat pump installed, is it possible to run both low heat and heat pump at the low blower setting?
    The matching coil is supposed to add 0.041" dry, 0.071" wet to the ESP at 700 cfm and .052", .089" at 800 cfm
    What that is comparing is (SCFM) vs. Pressure drop; dry & wet (In. WC) @ 700cfm & @ 800-cfm.

    I have never paid much attention to those numbers...

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