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  1. #1
    Join Date
    Jan 2005
    Location
    USA
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    1,460

    Frown AAON VCM control communication issue.

    I have an AAON RTU (heat pump) with the wattmaster vcm controls on it. We are having an issue with the supply air temp as it is not resetting off of outside air and the unit is putting out 43* air, too cold for the reheats to overcome and the building is cold. We have a lon card tied in to to the comm port and the points all seem to read ok, I have integrated the site via a j700 with spyder controlled reheat vav's. I am experiencing a few issues.

    1: I am not sure if we are adjusting the correct point over lon for the supply temp. I am using SaClSt set at 55* and the SaHtSt set at 75*. I have of course played with these settings with no difference. The unit does ok when it is hot out and controlls the cooling well.

    2:The points are jumping around on UnitMode (from RemoteScheduleOverride to CurrentOutputForceMode) and the EconPos is jumping back and forth from 5% to 25%. The unit works fine as far as the Jace controlling the occupancy and the economizer is not actually driving back and forth as the point shows.

    3:When we power the unit down and unplug the lon card from the com port and plug in the system manager, we are unable to communicate with the unit. The units systems id is 1 as verified on the comm board. If we do a connect it says something to the effect of unit not found, we get the same result if we do a loop scan.

    Any assistance would be appreciated. I have not had luck with aaon tech support in the past but that will be my next call on Monday
    Thanks
    "It's always controls"

  2. #2
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    1,016
    Do you have the System Manager jumpers and configuration set to stand alone mode?

  3. #3
    Join Date
    Jan 2005
    Location
    USA
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    1,460
    Quote Originally Posted by hvac69 View Post
    Do you have the System Manager jumpers and configuration set to stand alone mode?
    Yes jumpers and config are in stand alone mode.
    "It's always controls"

  4. #4
    Join Date
    Jul 2006
    Location
    Southern California
    Posts
    256
    1. Did you get their "ruinet" software to configure the Watt Stopper communications and points?
    2. Read up on their sequence of operations; there are some functions that can disregard your remote settings, such as when the unit goes into dehumidification mode; which is what it sounds like it is doing to you.
    (just a "wag" because you did not provide much info)
    Aaon units with Watt Stopper controls do work. You have to learn and understand the limitations of their remote point management, regardless if it is Lon or BACnet.
    In the future, post what make, model, and version, of Aaon and Watt Stopper controls you are working on.

    Just a little tip, don't rely upon their software comm unit address setup; use the dip switches; this has solved many an Aaon "power off, then back on", comm loss.

    Good luck

    Drac
    "We are what we repeatedly do. Excellence, then, is not an act, but a habit" Aristotle

    Remember to "Pay it Forward"; help out the newer generation of techs, remember someone during our career helped us! ("Pay it Forward" was by someone smarter than me!!)

  5. #5
    Join Date
    Jan 2005
    Location
    USA
    Posts
    1,460
    Quote Originally Posted by dracula View Post
    1. Did you get their "ruinet" software to configure the Watt Stopper communications and points?
    2. Read up on their sequence of operations; there are some functions that can disregard your remote settings, such as when the unit goes into dehumidification mode; which is what it sounds like it is doing to you.
    (just a "wag" because you did not provide much info)
    Aaon units with Watt Stopper controls do work. You have to learn and understand the limitations of their remote point management, regardless if it is Lon or BACnet.
    In the future, post what make, model, and version, of Aaon and Watt Stopper controls you are working on.

    Just a little tip, don't rely upon their software comm unit address setup; use the dip switches; this has solved many an Aaon "power off, then back on", comm loss.

    Good luck

    Drac
    1: We had factory start up come out to set the unit up. I am not sure what they used for that. After they were finished I installed a PT-Link II Lon card. I used the software that came with the card (not sure what it was called) to set the card up and then plugged into our J700. The only points we have linked to for override are the supply set points and the schedule the rest are proxied in but only for monitoring. If the unit is indeed going into dehumidification then that will have to be adjusted or disabled as the outdoor air temp was 10* and the humidity was 0 during this issue.

    2:RTU model RN-031-8-0-E609-000. Watt master VCM controls from ORION systems I will have to look for the version at next site visit.

    3: Dip switch is set at 1, I have cycled power to the unit and was still unable to communicate via the system manager. The lon card communicates fine when we unplug the system manager and plug it back in.

    I have been monitoring the site as I have not been able to revisit the problem yet but since last visit the unit has worked flawlessly.
    "It's always controls"

  6. #6
    Join Date
    Jan 2005
    Location
    USA
    Posts
    1,460
    Just a follow up. In the PT-Link II Lon technical guide it states "All programming of controllers must be done using the modular service tool. The modular system manager should not be used on a system that has a pt-link installed." Even though we disconnected the pt-link and cycled power before plugging in the system manager, I am not sure but this maybe the reason that the system manager would not access the vcm.
    "It's always controls"

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