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  1. #14
    Join Date
    Sep 2005
    Location
    Bay Area, CA
    Posts
    843
    Quote Originally Posted by mark beiser View Post
    I use a Testo H-2.
    I try to get my wet bulb readings as close to the evaporator coil as possible, even if I have to drill a 1/2" hole in the side of a furnace.
    The hole also doubles as an inspection hole to insert my fiber optic scope to check that the coil is clean.
    I'd totally do that if most furnaces around here weren't in a closet. I also use the h2 for my wet bulb temp needs as well.
    Global Warming or: None like it hot
    No pleasure, no rapture, no exquisite sin greater... than central air. -Dogma

  2. #15
    Join Date
    Jun 2004
    Location
    Location:Raleigh NC
    Posts
    9,486
    Quote Originally Posted by mark beiser View Post
    I use a Testo H-2.
    I try to get my wet bulb readings as close to the evaporator coil as possible, even if I have to drill a 1/2" hole in the side of a furnace.
    The hole also doubles as an inspection hole to insert my fiber optic scope to check that the coil is clean.

    I do get lazy at times and just check at a return grill, if I know the return duct system is very tight, but better than 90% of the time I get the reading at the equipment.

    In my area, there are very many homes built with the HVAC equipment in the attic, and a reasonably extensive return duct system, often incorporating a number of floor level returns that pull through wall cavities.
    Checking the WB and DB temps at the coil is not only much more accurate, but it also allows me to spot problems with leaky returns, which are common, or significant leakage around the blower access, which is even more common.
    Hey Mark good to see you posting again have seen much of you lately
    If you help others then you are a Success

  3. #16
    Join Date
    Feb 2007
    Location
    Central NJ
    Posts
    458
    testo h-2 all the way. i've set up and checked fan speed to a/c ton requirements using a typical slide rule and sure enough gotten it dead on target! one of my favorite tools. keeps my sling nice and stored away!
    You have to pay your due's before you pay the rent!

  4. #17
    Join Date
    Oct 2007
    Location
    ATLANTA
    Posts
    120
    Quote Originally Posted by MechAcc View Post


    http://www.efficientcomfort.net/Charging&TDchart.pdf

    By measuring the entering dry bulb and wet bulb temperature of the air entering the evaporator and using the charging chart a better job can be done at measuring system performance.

    Measuring system airflow measuring return and supply wet bulb temperatures you can determine the system's btu capacity outline in the steps in Carriers "Service Technicians Handbook."

    Good question.

    Hi

    Is there a similar chart,formula or guide line to use with TXV coil systems for target SH and Evaporator leaving air temperature?


    Thanks
    Last edited by AtoZhvac; 04-27-2009 at 09:31 PM. Reason: add

  5. #18
    Join Date
    Feb 2008
    Location
    Waffleville
    Posts
    10,339
    Quote Originally Posted by Lee Adams View Post
    Hi

    Is there a similar chart,formula or guide line to use with TXV coil systems for target SH and Evaporator leaving air temperature?


    Thanks
    here ya go http://efficientcomfort.net/jsp/PsychroCoilCalc_Web.jsp
    If Guns Kill People, Do Pencils Misspell Words?

    http://www.youtube.com/watch?v=An2a1...eature=related

    Before we work on artificial intelligence why don't we do something about natural stupidity?

  6. #19
    Join Date
    Oct 2007
    Location
    ATLANTA
    Posts
    120
    Quote Originally Posted by beachtech View Post

    Hi

    Do you know if there is a software version of this that could be carried along in a laptop. Or a slide rule version to keep in the truck?

    Thanks

  7. #20
    Join Date
    Nov 2008
    Location
    DFW,TX
    Posts
    2,163
    i guess i am just doing this wrong but i use my digital stick thermmoeter,wet the end with some spit and stick it in the return plenum or grill ,then just above the indoor coil in the air stream while running,then take outdoor temp and hook up my guages and take pressure readings and the sh or sc reading using this information and an old trane chart i have to get where my sh or sc should be for that particualr day..

    I guess this isnt as accurate but seems to work for me to this point..

  8. #21
    Join Date
    Feb 2008
    Location
    Waffleville
    Posts
    10,339
    Quote Originally Posted by Lee Adams View Post
    Hi

    Do you know if there is a software version of this that could be carried along in a laptop. Or a slide rule version to keep in the truck?

    Thanks
    i don't know of it, but am sure someone here does
    If Guns Kill People, Do Pencils Misspell Words?

    http://www.youtube.com/watch?v=An2a1...eature=related

    Before we work on artificial intelligence why don't we do something about natural stupidity?

  9. #22
    Join Date
    Feb 2008
    Location
    Waffleville
    Posts
    10,339
    Quote Originally Posted by acguytx View Post
    i guess i am just doing this wrong but i use my digital stick thermmoeter,wet the end with some spit and stick it in the return plenum or grill ,then just above the indoor coil in the air stream while running,then take outdoor temp and hook up my guages and take pressure readings and the sh or sc reading using this information and an old trane chart i have to get where my sh or sc should be for that particualr day..

    I guess this isnt as accurate but seems to work for me to this point..
    i would say that the last part there is the most acurate i have used a regulaer thermomter and parts of a wet peice of coton before to get out of a pinch due to a dead battery
    If Guns Kill People, Do Pencils Misspell Words?

    http://www.youtube.com/watch?v=An2a1...eature=related

    Before we work on artificial intelligence why don't we do something about natural stupidity?

  10. #23
    Join Date
    Apr 2005
    Location
    new jersey
    Posts
    752
    Quote Originally Posted by MechAcc View Post


    http://www.efficientcomfort.net/Charging&TDchart.pdf

    By measuring the entering dry bulb and wet bulb temperature of the air entering the evaporator and using the charging chart a better job can be done at measuring system performance.

    Measuring system airflow measuring return and supply wet bulb temperatures you can determine the system's btu capacity outline in the steps in Carriers "Service Technicians Handbook."

    Good question.
    I just got mine the other day.

  11. #24
    Join Date
    Jun 2004
    Location
    Location:Raleigh NC
    Posts
    9,486
    Quote Originally Posted by Lee Adams View Post
    Hi

    Do you know if there is a software version of this that could be carried along in a laptop. Or a slide rule version to keep in the truck?

    Thanks
    I use this
    http://www.the-snowman.com/wetbulb2.html
    you can download the Excel link to your Laptop
    If you help others then you are a Success

  12. #25
    Join Date
    Jan 2008
    Posts
    63

    Wink

    great formula,is there one like that for desigh subcool? not all txv systems have that information on name plate like trane,rheem for example or you just cant read it.]

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