Results 1 to 9 of 9
  1. #1
    Join Date
    Feb 2005
    Posts
    2
    I've inherited a job with VAVs that have been retrofitted with electronic controllers. They still have pneumatic damper acuators with a range of 5-10 psi. The transducers output 8-13 psi. Is this an acceptable way to do this or should the actuators have been matched to the output range of the transducers?

  2. #2
    Join Date
    Aug 2000
    Location
    USA
    Posts
    4,995
    Cant you adjust the transducer to match the actuator spring range?
    Your poor planning does not constitute an emergency on my part!!!!

  3. #3
    Join Date
    Feb 2005
    Location
    Where it's dark & damp
    Posts
    609
    I wouldn't think so. I would hope you could scale the transducer. I would think it was a little backwards to retrofit a pneumatic transducer considering the fact that an electronic VAV sized actuator would be around the same price if not cheaper than the transducer. The only exception I would think of would be the older Trane brand boxes with the globe style air valve and the pneumatic "baloon" style dampers where there would be no practical solution other than replacing the box or a transducer.

  4. #4
    Join Date
    Feb 2005
    Posts
    2
    The transducers are CP-8551 by seibe/invensys and I don't think they are adjustable, at least there's nothing in the accompining paperwork to say so.

  5. #5
    Join Date
    Feb 2005
    Posts
    50
    You're going to have to change something.If we're
    talking a Kreuter vav box or similar,they have 8-13
    actuators.Or return your xducers for a model with adjustable start point[lessen learned:always buy the
    convertible xducer,avoid the ah ****].Also if you are
    stuck,check all the damper actuator mngrs,somebody will have an 8-13 that will fit.

  6. #6
    Join Date
    Dec 2002
    Posts
    603
    If the spring range is 5-10 # and the dampers are set for this spring range then that makes the mid position at7.5# So if the transducers start at 8# then as soonas theyget there and supply this pressure to the motor it will go to just pass mid position. You will have the same problem coming the other way So the solution is to change the springs or the transducers.

  7. #7
    Join Date
    Jul 2001
    Location
    Canada
    Posts
    1,824
    What are you using to control the transducers, is it a INVENSYS controller ?

    The older CP 8551's had a bit of adjustment in them.

  8. #8
    Join Date
    Jul 2002
    Posts
    936
    Johnson has somthing like a "sequencing cumulator" etc.. It has a little spring inside you can adjust to counteract the higher pressure and change 8-13 into 5-10.

  9. #9
    Join Date
    Mar 2003
    Posts
    7,326
    do those transducers have internal feedback? if not you may be able to lower the air supply to that area and get half decent results until you can get the customer to spring for the new actuators.

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