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air flow / velocity meter

wondering whats the general thoughts on them .I have a supco unit which i have used to check my unico installs and it seems fairly accurate .I have been asked to test a and balance a 100 % make up air system .we had nothing to do with the install besides order the unit from what they specified .I am wondering will this supco DAVM+ will be acceptable or weather we should fork up over a grand for a better unit which will be used once .These reading are being ordered by the mech engeeners for them to get a CO .Again we had nothing to do with any thing on the install ,duct sizing or cooling sizing .We already kinda know that it will be screaming due to the duct sizing but we are only to get the readings and balance it out there are also no dampers any where and this was a union tin job wrapped with bubble wrap .Any input to as weather this meter will be accaptable would be great.Peace and good luck  clammy
R.A. Calmbacher L.L.C. HVAC
NJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating


  • meplumber
    meplumber Member Posts: 678
    You need a Balometer

    To properly balance a system like that you would have to use a Balometer.

    These can be calibrated for the diffuser and will give you volume and velocity with allowances for diffuser type. These models can handle the air flow that you are gonna see on a 100% mua system.

    Good Luck.
  • How much usage?

    It all boils down to how much use will the instrument be getting and how accurate do your readings need to be.

    Do you need actual air volume readings, or are you willing to calculate the air volumes if you know the velocity and the cross-sectional area of the duct?

    Bells and whistles are a good thing, but they also cost money. At the school I use both a balancing hood (as posted already) as well as a velometer. With the balancing hood, you are able to read the precise air volume coming from a particular supply register. With a velometer, you must traverse the duct, taking multiple readings to obtain the average, and then use this average to calculate the air volume.

    Hand held velometers are much less expensive than are balancing hoods, but they require more time and energy to get accurate readings.

    As was mentioned, you are probably better off with a balancing hood for this one.

    Good luck!
  • furnacefigher15
    furnacefigher15 Member Posts: 514
    Sub it out.

    If you are never going to use the tool again, then get a sub to do it.

    Besides, if Mr. Engineer is declaring the need for test and balance, then he likely won't settle until it is a "certified test and balance"

    If you don't own a balometer then I'll go out on a limb and say you aren't a certified air balancer.

    And further more, there is no point in buying the big guns for a job with nothing to balance anyway.

    For those that may not know, the dampers built into the supply diffusers will not divert flow, but only reduce volume to that terminal device.
  • Noise is the Issue

    Good point worth reiterating.

    The "dampers" that are located within the supply registers are not intended to be used as the sole means of balancing a system. Doing so will often result in excessive noise in the conditioned space.

    A Happy and Healthy New Year to All!
This discussion has been closed.