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  1. #1
    Join Date
    Jun 2004
    Posts
    72

    SWUA increase in Airflow

    I have a SWUA Trane package unit (40 tons) with airside Economizer and a water cooled condenser. I've recently added VFD control to the fan, and I'm considering removing the inlet vanes on the two fans. I've heard that you can increase the airflow from these units by doing this. Is this true? I don't want to spend the man hours removing the vanes and not get any results. Does anyone have any experience with this or had any luck by doing this?
    Thanks

  2. #2
    Join Date
    Oct 2002
    Posts
    398
    Don't bother, just pin them open.

  3. #3
    Join Date
    Oct 2003
    Location
    edgewood nm
    Posts
    73
    SIRTAB is right. If you lose the drive you will have back up for volume control.

  4. #4
    Join Date
    Sep 2000
    Location
    Miami, Fla. USA
    Posts
    417
    Originally posted by weezer
    SIRTAB is right. If you lose the drive you will have back up for volume control.
    Good luck with the spare thing.

  5. #5
    Join Date
    Sep 2000
    Location
    Miami, Fla. USA
    Posts
    417

    Re: SWUA increase in Airflow

    Originally posted by pincheal
    I have a SWUA Trane package unit (40 tons) with airside Economizer and a water cooled condenser. I've recently added VFD control to the fan, and I'm considering removing the inlet vanes on the two fans. I've heard that you can increase the airflow from these units by doing this. Is this true? I don't want to spend the man hours removing the vanes and not get any results. Does anyone have any experience with this or had any luck by doing this?
    Thanks
    Just curious. How are you controlling the VFD reference.

  6. #6
    rubobornot Guest
    I was told that the vanes help guide the air into the vortex and removing the vanes will cause the blower to move less air at a higher blower amp draw due to turbulance thru the blower.

  7. #7
    Join Date
    Jun 2004
    Posts
    72
    Thanks for the input, I was leaning towards the same direction. I can see where removing the vanes would cause turbulence and that makes sense to me.
    As for the VFD reference, we have a DDC system that has a 0"-5" WC Pressure Sensor, that senses duct pressure, and maintains a user defined setpoint (usually around 1.25"WC) which then sends a 0-10vdc signal to our new ABB Freq.drives. We have on an average of 20-25zones per floor per unit, and when they are satisfied the pressure rises in the duct and the VFD slows, but it doesn't slow down to where we comprimise min. fresh air requirements for the entire floor. This system also incorporates a CO2 sensor that is linked to the economizer output (via software) and opens the economizer to lower the CO2 levels, but there are safeguards to eliminate the probability of bringing in too much OSA when it's too hot outside or too cold.
    I can go on, but this post would be really long, the system is new and works really nice for our application.
    Thanks again.

  8. #8
    Join Date
    Sep 2002
    Posts
    1,389

    pincheal

    On the older boxcars you have to jumper out the end switch in the guide-vane damper motor. It would shut off the unit when the motor went to the closed position. The motor, if left hooked up electrically, will track the vfd through the original air pressure switches while the VFD if ramping the motor. Also, you will want to add the safety circuit (dry contacts)in the VFD to stop the cooling whenever there is a VFD shutdown. Wether it be for normal operation or safety. It normally requires its own relay unless the contacts are heavy enough to carry the normal control circuit for cooling. If you have heating, you will then need a two-pole relay unless the VFD has two sets of adequate dry contacts.
    Good luck.

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