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  1. #1
    Join Date
    May 2019
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    Converting Trane Voyager from VAV to CV?

    So I have a customer with Trane Voyager circa 2008 that is a VAV unit. The unit is not serving VAVs and basically I want to run it as a CV unit such that I can used the R, G, W terminal strip. From everything I've read if its a VAV unit that terminal strip is locked out in the RTRM board. The full story is that this unit has been half gutted where the BAS is controlling the cooling contactors and VFD directly. The issue is getting the unit to heat. Its not so simple to get that gas valve, inducer fan, and ignitor to sequence from the BAS without the Trane boards being involved.

    I was wondering if I just removed the RTAM board if it would think its a CV unit and I could use R, W1, and W2. Any idea if this is possible?

  2. #2
    Join Date
    Nov 2011
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    If the BAS still works, just lock the speed drive at whatever Hz you need to get the job done. If you need to have high (cool) and low (heat), use the digital inputs on the drive for set speed operation.

  3. #3
    Join Date
    Feb 2016
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    Agree with CHOPS. Set the speed you want on the VFD and forget about.
    No man can be both ignorant and free.
    Thomas Jefferson

  4. #4
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    May 2019
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    Thread Starter
    Quote Originally Posted by WAYNE3298 View Post
    Agree with CHOPS. Set the speed you want on the VFD and forget about.
    Sorry, I guess I wasn't clear. I've got the drive set but I need to get the unit to heat. I don't want to do morning warmup or daytime warmup or any of that BS. I just want to say HEAT and start heating until I say stop. That would work with with the regular R, W interface, but since it was shipped as a VAV unit that part of the RTRM doesn't work. Since the RTRM is talking to the IGN through a comm interface so I can't just fake a contact with a relay.

    Hopefully that makes more sense...

    Any thoughts on taking out the IGN and replacing with a universal furnace control board? Or is that a really bad idea? Thinking a White-Rodgers 21M51U-843 might do the trick.

  5. #5
    Join Date
    Jan 2010
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    In reality, any changes you make from OEM puts you in the hot seat should things go bad. You'll be the first in line as far as litigation. Is it your equipment ?

  6. #6
    Join Date
    Feb 2016
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    Sounds like now you need temperature averaging with the results sent to the AHU. There are control guys here that will fix you up when they see this post. That's not my specialty.
    No man can be both ignorant and free.
    Thomas Jefferson

  7. #7
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    May 2019
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    Thread Starter
    Quote Originally Posted by WAYNE3298 View Post
    Sounds like now you need temperature averaging with the results sent to the AHU. There are control guys here that will fix you up when they see this post. That's not my specialty.
    Ha! I am the control guy. Oh well, I was afraid this would go down a rat hole.

    One of those things I don't really want to do but the customer wants something done. I'm trying my best to talk them out of it but no luck yet.

  8. #8
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    May 2019
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    Thread Starter
    Yeah thats why I'd really like to use the RTRM and not replace the IGN. Ugh, this is one of those things I was hoping the customer would forget about but haven't been able to talk them out of it yet.

  9. #9
    Join Date
    Nov 2011
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    Just order a RTRM board for a constant volume unit, and get the stat interface board (if the new board doesn’t have the terminals).

    Why reinvent the wheel when you can get the OEM parts to make it happen?

  10. #10
    Join Date
    Feb 2016
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    I wasn't taking a poke at you pmoo. There is always someone that has an experience you don't no matter how extensive your experience is. I'm one of the oldest on here and it happens to me constantly.
    No man can be both ignorant and free.
    Thomas Jefferson

  11. #11
    Join Date
    May 2004
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    I think the RTRM boards are all the same and configure themselves depending on the other boards connected. The old UCP used a jumper to config CV or VAV along with other added boards. But you will be operating the unit in manner it was not designed for and you will need to change control of the fan as the RTAM controls it presently. Page 40 of this document explains the RTRM configuration a little.

    https://www.trane.com/content/dam/Tr...34J-EN_IOM.pdf

  12. #12
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    May 2019
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    Quote Originally Posted by WAYNE3298 View Post
    I wasn't taking a poke at you pmoo. There is always someone that has an experience you don't no matter how extensive your experience is. I'm one of the oldest on here and it happens to me constantly.
    Ha, no problem. Honestly, I'd be rolling eyes at myself and kind of am on this one.

  13. #13
    Join Date
    May 2019
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    Awesome, thanks! This is hopefully exactly what I'm looking for. Based on this I think I may just be able to flip a couple dip switches and make it think its a CV unit.

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