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  1. #1
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    Trane VariTrac Retrofit

    I'm looking at a job with a Trane control system. The system has 3 RTUs, each with a bypass damper and VariTrac VAVs. I want to rip all that stuff out and put in an FX80 with PCGs and PCVs. The first problem that I see is that these VAVs don't seem to have the High/Low pressure tubes for the PCV controllers. Has anyone else ran into this type of system and/or done a retrofit?

    Also I think this system has UCM 4.0 VAV controllers

  2. #2
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    Sounds like a VVT system, not VAV.
    Propagating the formula. http://www.noagendashow.com/

  3. Likes bolt950rider liked this post.
  4. #3
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    Thread Starter
    Correct. It seems like a VVT type sequence with Trane VAV controllers and dampers

  5. #4
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    Given the size you might be able to integrate to it with a Maxline driver and your planned jace for less money.

  6. #5
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    If its VVT, then toss a VVT program at it and don't worry about the airflow pickups. Not normally used with VVT and even if you did, where are you getting your set points from?
    Propagating the formula. http://www.noagendashow.com/

  7. #6
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    I don't think I've ever set up a vav without the airflow pickups. I'm not sure how to make a PCV controller work without them. I think the system works now with voting on whether the space needs heat or ac. I would like to get away from that because there are issues with it now. I was going to get my flow setpoints based on the size of the vav/vvt box.

  8. #7
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    Jun 2009
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    JCI sells a PCV1626 without the airflow sensor. There are canned commercial zoning files for the PCVs and PCG that work pretty well out of the box.
    UA LU 562

  9. #8
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    Quote Originally Posted by Igotworms View Post
    I don't think I've ever set up a vav without the airflow pickups.
    That's because its not a VAV system.

    Quote Originally Posted by Igotworms View Post
    I'm not sure how to make a PCV controller work without them. I think the system works now with voting on whether the space needs heat or ac. I would like to get away from that because there are issues with it now. I was going to get my flow setpoints based on the size of the vav/vvt box.
    How are you going to deal with heating? The RTU is currently blasting down heat when the spaces need it during occupied times. Normally there isn't secondary heat in the zones on these systems. Most VAV programs ain't setup to deal with hot air during occupied times. Being at max cool when this happens...not good. I don't deal with JCI much, but I think they have a VVT programs in the Q&A bs.
    Propagating the formula. http://www.noagendashow.com/

  10. #9
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    I don't see secondary heat or re-heats in the zones and I don't think there is Q and A for VVT in JCI software. I think VVT is a garbage system that's why I'm reaching out on here to see if anyone has done a retrofit for this type of system. Trane is the incumbent in this building and they are not interested in bidding it. I think I might walk away from this one too.

  11. #10
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    Its typically more than just a controls swap to switch it to VAV. Only heat source in the RTU in most of them, so you still stuck with some type of voting and then logic to swap the action of the damper. Just adding airflow isn't going to do much for you.
    Propagating the formula. http://www.noagendashow.com/

  12. #11
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    Quote Originally Posted by Igotworms View Post
    I don't see secondary heat or re-heats in the zones and I don't think there is Q and A for VVT in JCI software. I think VVT is a garbage system that's why I'm reaching out on here to see if anyone has done a retrofit for this type of system. Trane is the incumbent in this building and they are not interested in bidding it. I think I might walk away from this one too.
    I did this exact job with PCV's and PCG's last year. Only source of heat is in RTU's. I ended up installing a duct sensor on the inlet of each zone damper that way if the zone needs cooling and the DAT is higher than suitable for cooling, the zone damper closes. Works pretty well. The job was 6 RTU's with 63 zone dampers. Had to do everything with custom logic. I also used PCV 1628's because the Trane boxes used an incremental signal for the damper control.

  13. #12
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    Quote Originally Posted by The Reaper View Post
    I did this exact job with PCV's and PCG's last year. Only source of heat is in RTU's. I ended up installing a duct sensor on the inlet of each zone damper that way if the zone needs cooling and the DAT is higher than suitable for cooling, the zone damper closes. Works pretty well. The job was 6 RTU's with 63 zone dampers. Had to do everything with custom logic. I also used PCV 1628's because the Trane boxes used an incremental signal for the damper control.
    No prebuilt logic for VVT systems?? I would think they would share DAT from the AHU.

  14. #13
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    They do have some pre-built stuff for VVT but I don't care for it. That's just me personally though. This job was done in phases and the Jace went online at the end. I needed to make the system as stand-alone as possible.

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