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  1. #1
    Join Date
    Oct 2007
    Location
    Anaheim, CA
    Posts
    141

    Question Wet Bulb measurements

    I have a couple of questions for all of you smart technicians! I appreciate any information you can provide.

    How many technicians are measuring Wet Bulb temperatures? (out of 100 techs, how many measure wet bulb?)

    Where do technicians take these measurements? Inside the building? At the return Grille? In the return duct work? in the return plenum?

    What do you use to measure the wet bulb temperature?

    What do you use the wet bulb measurements for?

  2. #2
    Join Date
    Jul 2000
    Location
    NW IL.
    Posts
    3,935


    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.
    Aircraft Mechanical Accessories Technician. The Air Force changed the job title to Air Craft Environmental Systems Technician. But I've decided I'll always be a Mech Acc.

  3. #3
    Join Date
    Sep 2002
    Posts
    4,970
    Have to admit I still use my sling sycrometer I have had for years.

    It may not be as fast but has worked for years so ........ I'm fine with it.

    Have more important things as far as tools to buy then to replace something I know works.

    Guess electronic might be easier then having my little bottle of distilled water & sling ........ but then I know its accurate

  4. #4
    Join Date
    Jun 2004
    Location
    Location:Raleigh NC
    Posts
    9,486
    At the return mostly or the return plenum
    Amprobe digital
    TO know the Evp load
    If you help others then you are a Success

  5. #5
    Join Date
    Feb 2008
    Location
    Waffleville
    Posts
    10,339
    a regular member trying to get info without being a pro...
    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. #6
    Join Date
    Oct 2007
    Location
    Anaheim, CA
    Posts
    141
    How many posts before I am a pro?

    I am a Fieldpiece guy and you guys...the HVAC technicians... are the ones that drive our product development!...I like to gather as much information as possible from you guys because you are the ones that will use our products for a living!

    I like to keep my mouth shut and ears...eyes...open as much as possible. That's why I only have a few posts.

  7. #7
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,312
    are you saying that you work in the R&D at fieldpiece??

    if that is in fact true say it loud and clear here and you'll get more than enough ideas for product development.

    as for pro statues you need to apply. contact the forum mods

  8. #8
    Join Date
    Feb 2008
    Location
    Waffleville
    Posts
    10,339
    Quote Originally Posted by ault51 View Post
    How many posts before I am a pro?

    I am a Fieldpiece guy and you guys...the HVAC technicians... are the ones that drive our product development!...I like to gather as much information as possible from you guys because you are the ones that will use our products for a living!

    I like to keep my mouth shut and ears...eyes...open as much as possible. That's why I only have a few posts.
    only 15 posts, so you are there. apply for promembership it may takes a couple days as all the guys on the membership committee are volunteers and work full time jobs as the rest of us do

    how do you become any better if you don't open your mouth and ask???
    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. #9
    Join Date
    Apr 2007
    Posts
    623

    Well.......... You use it for charging

    For piston/ fixed metering device systems only!!!!!! IWB x 3 - 80 - Outdoor AMB / 2 = Superheat

  10. #10
    Join Date
    Sep 2005
    Location
    maui
    Posts
    389
    Quote Originally Posted by aintitfun View Post
    For piston/ fixed metering device systems only!!!!!! IWB x 3 - 80 - Outdoor AMB / 2 = Superheat
    what????
    What cant be done correctly shouldn't be done at all

  11. #11
    Join Date
    Sep 2005
    Location
    maui
    Posts
    389
    wow I did that calculation several times against a generic charging chart and it came real close every time

    guess you learn something new every day thanks aintitfun
    What cant be done correctly shouldn't be done at all

  12. #12
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,312
    Quote Originally Posted by aintitfun View Post
    For piston/ fixed metering device systems only!!!!!! IWB x 3 - 80 - Outdoor AMB / 2 = Superheat
    i use mine for more than that. the formunla you qoute is for superheat but there are other charts for proper air flow that require wet bulb and dry bulb mesurements of the evaperator entering air to calculate supply dry bulb.

  13. #13
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    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.
    If more government is the answer, then it's a really stupid question.

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