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  1. #1
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    JCI VMA1420 questions

    Hi all. I have a VMA1420 vav controller that I have some questions on. This vav uses a floating reheat valve so it has a BO to open and a BO to close. The wiring diagram shows that typically BO #2 & 3 control the reheat valve. How do you configure what number outputs are actually being used? This is a brand new controller. I downloaded the configuration to the controller and tried commisioning it. I opens the reheat valve but does not close it. I suspect may the wrong output is being used but need to bring another tech along a recheck it so one can can run the computer while another guy is at the VAV. Don't have the hvac pro software on my laptop yet. Thanks guys.

  2. #2
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    Refer to the cut sheet. If you notice, terminals 1 and 2 are the incomming power. Terminal 1 must be the 24VAC "Common" and Terminal 2 the 24VAC "Hot" if you get that straight it should work correctly as long as you have the Valve operator wired right. I don't know what brand of valve it is but check to make sure that "BO-COM" goes to the "Common terminal on the valve, BO-2 goes to the "Open" terminal and BO-3 goes to the "Shut" terminal.

    If I remember right the VMA's switched terminal 2 at the BO's but I may have that backwards, not much help am I.

    Check the JCI web site for more info.
    If sense were so common everyone would have it !

    All opinions expressed are my own. Any advice provided is based on personal experience, generally accepted fact or publicly available information. As such, it is worth exactly what you paid for it, not a penny more not a penny less !!

  3. #3
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    If the VMA has a fan powered box, then BO-1 will be for the fan and BO-2 and 3 will be for the floating reheat. If there is no fan, then BO-1 and 2 will be for the reheat. I'm going off of memory so like Kelly said, check the JCI website. Good luck.

  4. #4
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    Thanks for the quick response. So are you saying that the configuration of the BO's can't be changed? If you pull the outputs tab up in the hvac pro it shows that BO #1 & 2 are being "used" which doesnt make sense as BO #1 & 2 do not share a common. I wired the controller to use 2 & 3 but valve not closing. I want to check the configuration to make sure somebody didn't do something funky. All I see in the output screen is what output is being used but it doesn't say for what. Am I looking in the wrong location? Another thought, when it says that BO 1 & 2 are used is that the actual output number or just how many outputs are used. Thanks again.

  5. #5
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    I must have been typing when the Reaper replied. There is no fan so maybe BO 1 & 2 is correct. If so would you need a jumper to connect the commons? Thanks.

  6. #6
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    Quote Originally Posted by chillerguy81 View Post
    Thanks for the quick response. So are you saying that the configuration of the BO's can't be changed? If you pull the outputs tab up in the hvac pro it shows that BO #1 & 2 are being "used" which doesnt make sense as BO #1 & 2 do not share a common. I wired the controller to use 2 & 3 but valve not closing. I want to check the configuration to make sure somebody didn't do something funky. All I see in the output screen is what output is being used but it doesn't say for what. Am I looking in the wrong location? Another thought, when it says that BO 1 & 2 are used is that the actual output number or just how many outputs are used. Thanks again.

    Sorry, yes that is the Actual outputs that you have to wire to. That may be your problem right there. Don't go by the diagram if you know which BO's the controller is programmed for. You may need to disregard the following if that's the case. Plus BO-1 is always "Open" and the VMA defaults to a Normally Open Valve.

    Look at the "PAO" (or is it PAT) under outputs. Double click on it and it opens another window. You should get more info there. If the outputs are assigned to BO-2 and BO3 then it is possible that you may have had a "Fan" at one point but someone deleted it via the Q&A, just a guess. And no, you do not have to jumper the BO-Com terminals. Based on your description I think there are 3 possibilities: 1)the power is rolled. 2) the Valve is mis-wired 3) the triac for BO-3 is toast. 1 and 2 are easy to correct. 3 will require you to re-assign the outputs from 2 and 3 to 4 and 5. I can't remember how to do that right this minute. I look it up and post if I find it.
    Last edited by Cagey57; 01-09-2010 at 09:56 PM. Reason: Duh, read the entire post CCI
    If sense were so common everyone would have it !

    All opinions expressed are my own. Any advice provided is based on personal experience, generally accepted fact or publicly available information. As such, it is worth exactly what you paid for it, not a penny more not a penny less !!

  7. #7
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    Thanks again, I'll dig into it next week. I did download the manual from JCI's website as well, I didn't think they would have that much info on there.

  8. #8
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    OK. Help's if I completely read the posts.
    I think I know what the problem is now. The cut sheet is general not specific.

    If you do not have a Fan the valve uses BO-1 and BO-2. The Valve
    "Opens" (wired to BO-2) and does not close (wired to BO-3). Move BO-2 wire to BO-1 and move BO-3 wire to BO-2. Then using HVAC-Pro doubleclick on "PAO" and change Polarity to Reverse.

    The Valve is opening and not closing because the VMA is energizing BO-2 to "Close" the valve because the polarity is "normal". Normal Polarity assumes that the valve is Normally Open: BO-1 to Open, BO-2 to close. BO-3 is not defined so nothing happens. Therefore the Valve is wired to operate as a Normally Closed Valve. Easy fix is to simply change the polarity to "Reverse" and move the wires at the VMA to the correct BO's. But make sure it works correctly before you walk away from it.

    Try using the "Help" that is in HVAC-Pro, you might be suprised just how much there is there !
    If sense were so common everyone would have it !

    All opinions expressed are my own. Any advice provided is based on personal experience, generally accepted fact or publicly available information. As such, it is worth exactly what you paid for it, not a penny more not a penny less !!

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