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  1. #1
    Join Date
    Feb 2009
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    Central Oklahoma
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    Economiser 2-10 vdc signal

    I have a building that is under construction. The engineer has designed a smoke evacuation strategy that requires Carrier economisers to drive full open. I contacted Carrier tech support and they in turn called their engineer who came up with a schematic. This schematic requires closing of a relay that sends 24vac to the 2-10 vdc control input on the damper motor while opening the 2-10 vdc signal. Has anyone seen this done? Will it work without burning up the actuator?

  2. #2
    Join Date
    Oct 2009
    Location
    Nova Scotia, Canada
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    172
    I've never heard of sending 24 vac to a vdc motor and it actually driving. Maybe I'm wrong but I'd make sure to have a replacement actuator with you when you try it. Carrier should cover it when it burns up

  3. #3
    Join Date
    Feb 2009
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    Central Oklahoma
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    Quote Originally Posted by CE-TECH View Post
    I've never heard of sending 24 vac to a vdc motor and it actually driving. Maybe I'm wrong but I'd make sure to have a replacement actuator with you when you try it. Carrier should cover it when it burns up
    That was my initial thought. Have a bunch of spares on hand. But seriously, the actuator is 24vac but normally is driven by a 2-10 vdc signal from the honeywell module based on minimum position, free cooling, co2, etc.

  4. #4
    Join Date
    May 2004
    Location
    Rapid City, SD
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    7,415
    If'n it were me (and it's not), I'd probably throw a 24v relay up there and use that, then wire your economizer through the relay.

    I just replaced one of these actuators (if it's the style I'm thinking), looks almost identical to a mod motor for a boiler. The one I put in was 24vac, but it was also driven by 24vac.

    I'm no 'tronic expert, but I've always thought putting DC to an AC device leads to a whole lot of nothing happening. Put AC to a DC device and it might work once, right before it lets the smoke out.
    "If you call that hard work, a koala’s life would look heroic."

  5. #5
    Join Date
    Jun 2006
    Location
    New Jersey
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    4,336
    Quote Originally Posted by ltd View Post
    I have a building that is under construction. The engineer has designed a smoke evacuation strategy that requires Carrier economisers to drive full open. I contacted Carrier tech support and they in turn called their engineer who came up with a schematic. This schematic requires closing of a relay that sends 24vac to the 2-10 vdc control input on the damper motor while opening the 2-10 vdc signal. Has anyone seen this done? Will it work without burning up the actuator?
    Hopefully your are understanding the schematic wrong. 24vac to a 10vdc actuator is a quick burn out.

    You don't happen to have a model number of the economizer?

  6. #6
    Join Date
    Feb 2009
    Location
    Central Oklahoma
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    26
    Thhis is a Carrier Economiser IV, which I looked up on the Honeywell website as a W7212A1017.

  7. #7
    Join Date
    Sep 2007
    Posts
    374
    That won't work. You can't use an ac signal - the control won't respond. Call again. That is my understanding - let me know if I AM wrong.

  8. #8
    Join Date
    Feb 2009
    Location
    Central Oklahoma
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    I don't know what kind of electronics are inside this actuator. That's why I am asking the question of whether or not it will drive fully open with a 24vac signal. I wonder if the actuator sees this voltage as a max, sort of like a 10vdc signal. Initially, I thought the engineer was not seeing the same actuator, but then I thought differently.

  9. #9
    Join Date
    Dec 2009
    Location
    Southern US
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    504
    Just curious
    Is there a constant 10vdc signal availible?
    If so installing a 24vac relay with 10vdc to N/O would be a quick and simple solution.
    I'm good at making things cold...You can ask my first two wives!

  10. #10
    Join Date
    Feb 2009
    Location
    Central Oklahoma
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    There is a 2-10 vdc signal available from an AO on the building energy management controls board. That is one option I had considered in conjuncton with a relay, like you said. I thought that would be the easiest option. Until I got the drawing from the engineer, which although it is simple, may not work. So I am asking my fellow professionals for their opinions. Thanks.

  11. #11
    Join Date
    Dec 2009
    Location
    Southern US
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    504

    Got to love them engineers!!

    You may want to check with the BAS contractor to be sure your dc signal will be availible if the building goes intomoke alarm. And of course your 24ac would need to be pulled from a source that would also not be shut down.
    Obvious I know but needed to be said.
    I'm good at making things cold...You can ask my first two wives!

  12. #12
    Join Date
    Feb 2009
    Location
    Central Oklahoma
    Posts
    26
    Yeah, those engineers walk on water. Of course, the voltage supplies are all from emergency power, right? If not, more engineers screwed up. I have three methods I came up with to power this damper open during smoke purge. None of them matched the engineers, so I thought he or she might be right and I just didn't understand the inner workings of an HF23BJ054a Carrier actuator made in Germany.

  13. #13
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
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    3,709
    Quote Originally Posted by can2man View Post
    That won't work. You can't use an ac signal - the control won't respond. Call again. That is my understanding - let me know if I AM wrong.
    I just want to say that you are wrong. Should work I believe it is a belimo motor if I'm not mistaken. What the model number of the rtu?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

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