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  1. #1
    Join Date
    Jun 2006
    Location
    Palm Harbor,FL. (moved from PA.)
    Posts
    144

    digital air flow meter # wdcfm8951

    I was thinking on buying a digital air flow meter that measures air flow,wb Temps,humidity,dew point,and capacity in Btu's and its a general brand made by mannix.

    This would save me on buying separate meters if its not junk,anybody have one or know anybody that does? I was really interested in the btu measurement,I guess when you measure register flow you can get fpm,cfm,btu's,any feedback or advice appreciated.
    if you measure all registers and add up cfm's and then test air flow at furnace T.E.S.P and get your cfm total from there I was wondering how accurate your duct loss would be then giving a good idea how tight the ducts are? it seems this tool could do alot.

  2. #2
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,451
    I noticed the price, however, that is reasonable for anyone doing a lot of HVAC calls. The specs look fairly good, I personally, would get one.

    I had a Bacharach Sling Psychrometer that I used for the wet bulb temps.
    Getting the Supply Air wet bulb or %RH is difficult without such a meter, so that the air sample doesn't get diluted with higher room air temp & its lower humidity.


    I am retired & I don't have most of those test instruments now. From scratch, I rigged-up a a deflection scale anemometer. I reference its deflection number to my room A/C's velocity deflection on the scale, provides' me with a rough ballpark FPM velocity. I might put, the how to make one, on one of my web pages. No, I didn't find it on a web page search, but there are other totally different types you can find; maybe I should do another search?

    All anyone needs is an anemometer to get the fps, a thermometer & a room temp wet wool or cotton sock using a strong fan, etc., using simple formula' with a cheap calculator you can get the CFM & a psychrometic software program yields the BTUH. (See below.)

    With the information data below along with an accurate CFM airflow, we can ball-park its BTUH output
    Return Air temp DB &, WB or %RH: __
    Supply Air temp DB &, WB or %RH: __


    Except for the refrigerant pressures you can take most of the readings for us.
    My advice to anyone with an A/C or heat pump: get a low cost humidity gage at a local hardware store & see what the percentage-RH is in your home, we can cross-reference that to the wet bulb depression.

    If you know what BTUH it is delivering as compared to its Nominal Rating, you have a leg-up for calling a Tech to trouble shoot the system. - Darrell

  3. #3
    Join Date
    Jun 2006
    Location
    Palm Harbor,FL. (moved from PA.)
    Posts
    144
    Thanks for the reply U-darrell,I read some of your site very imformative info.

    I was reading a thread a couple a weeks ago or so and can't remember where.A person posted a answer and said they measured the flow with this and then listed a link showing a mannix air flow meter that was yellow,might have been this particular one I'm looking at, I hope they see and post on here about there experience with the mannix product.
    I really like testo's meters but can't afford to buy all at once needed to do above mentioned functions,figured this might be a good start for now.

  4. #4
    Join Date
    Jun 2006
    Location
    Palm Harbor,FL. (moved from PA.)
    Posts
    144
    Tried to buy one theyr'e discontinued.
    Whats a good meter to measure flow at registers?
    I'll buy a Testo H-2 to measure R.H and W.B Temps.

    Anyone know the formula to measure BTU's From the cfm,W.B ect. measured at the registers? I imagine that wdcfm8951 mannix airflow meter did the calcs for you.

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