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  1. #1
    Join Date
    Aug 2009
    Location
    Raleigh
    Posts
    105

    Default Need temperature probes for HVAC testing

    I've been using Taylor water-resistent units but the last few have been defective (could not calibrate). Looking for something better. Suggestions?

    F.I.R.E. Services

  2. #2
    Join Date
    Mar 2007
    Location
    Spring Hill (Nashville), TN
    Posts
    5,847

    Default Re: Need temperature probes for HVAC testing

    Quote Originally Posted by Randall Clark View Post
    I've been using Taylor water-resistent units but the last few have been defective (could not calibrate). Looking for something better. Suggestions?
    I had to Google Taylor water resistent etc.. I had no idea what it was.

    If you are talking about taking the temp in the supply plenumn try a simple digital cooking thermometer. Last one I bought was around $7 at WalMart.

    I stop taking Delta-T readings several years back. I only take temp readings now to confirm what I have found.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  3. #3
    Join Date
    Dec 2008
    Location
    Maryland
    Posts
    2,777

    Default Re: Need temperature probes for HVAC testing


  4. #4
    Join Date
    Nov 2009
    Location
    St Paul, MN
    Posts
    1,628

    Default Re: Need temperature probes for HVAC testing

    I use UEI PDT 550's. Keep the cooking thermometers in the kitchen.

    MinnesotaHomeInspectors.com
    Minnesota Home Inspectors LLC
    ASHI #242887 mnradontesting.com

  5. #5
    Join Date
    Jan 2011
    Location
    Guelph,Ontario
    Posts
    169

    Default Re: Need temperature probes for HVAC testing

    I put one temperature probe in the supply line,and one in the return,and the temperature difference should be about 20 degrees different,this indicates the system operates is operating properly.


  6. #6
    Join Date
    Feb 2008
    Location
    Chicago IL
    Posts
    1,984

    Default Re: Need temperature probes for HVAC testing

    Fieldpiece makes nice hvac testing equipment, you can also usually find some of their stuff on ebay.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  7. #7

    Default Re: Need temperature probes for HVAC testing

    When I went through HI training back in the dark ages I was told to look for a delta temperature of 12 -18 degrees F as in an indicator of proper AC function. I don't remember ever seeing that written down anywhere though. If I had to support that claim where would I find an authoritative source?

    Last edited by Marshall Brown; 09-20-2013 at 06:44 PM.

  8. #8
    Join Date
    Feb 2009
    Location
    St. Louis, Mo. area.
    Posts
    276

    Default Re: Need temperature probes for HVAC testing

    Quote Originally Posted by Marshall Brown View Post
    When I went through HI training back in the dark ages I was told to look for a delta temperature of 12 -18 degrees F as in an indicator of proper AC function. I don't remember ever seeing that written down anywhere though. If I had to support that claim where would I find an authoritative source?
    I was told 13 to 23 degrees in my training, but the HVAC guys say that using a TD isn't reliable, and not to use it. I still do, and if it falls outside my 13 to 23 degree guidelines, I report that the A/C may not be functioning as efficiently as it should, and recommend further evaluation and correction as needed by a qualified HVAC contractor.

    One of the guys I trained with was using magnetic temperature probes that stuck tight to the plenums, and didn't always want to slide out of the access holes. Does anyone know where I can find some of these? Most of the thermometers I get from an HVAC supply house are crap, but I eventually end up leaving them in the plenums, and can't justify spending a whole lot.


  9. #9
    Join Date
    Feb 2013
    Location
    nj
    Posts
    5

    Default Re: Need temperature probes for HVAC testing

    Quote Originally Posted by Harry Janssen View Post
    I put one temperature probe in the supply line,and one in the return,and the temperature difference should be about 20 degrees different,this indicates the system operates is operating properly.
    A temperature differential from return to supply is not an indicator that the system is operating correctly. You would need to calculate either the superheat of the the unit or if it has a txv the subcooling. If you want to know if the system airflow is correct for a properly charged system you would need to measure indoor drybulb,indoor wetbulb and the evaporator dry bulb and do the calculation. Also you need to know the refrigerant that is being used because of the different cooling properties. Unless you are trained and certified to work on HVAC I wouldn't make a statement on a systems operation other then it was working or not.

    Bill K
    Nationally certified Test And Balancing technician


  10. #10
    Join Date
    Mar 2008
    Location
    Charlotte NC
    Posts
    2,303

    Default Re: Need temperature probes for HVAC testing

    Quote Originally Posted by BillKace View Post
    A temperature differential from return to supply is not an indicator that the system is operating correctly. You would need to calculate either the superheat of the the unit or if it has a txv the subcooling. If you want to know if the system airflow is correct for a properly charged system you would need to measure indoor drybulb,indoor wetbulb and the evaporator dry bulb and do the calculation. Also you need to know the refrigerant that is being used because of the different cooling properties. Unless you are trained and certified to work on HVAC I wouldn't make a statement on a systems operation other then it was working or not.

    Bill K
    Nationally certified Test And Balancing technician
    What rules of thumb would you recommend be used to make the decision on whether or not to call for an HVAC contractor to make a full evaluation of the system? Remember as HI's we do not attach gauges but are expected to make an educated guess regarding the status of the system. I agree that the delta T should not be the only indicator but would like to have your input.

    The beatings will continue until morale has improved. mgt.

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