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  1. Replies
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    5,936

    How do you recommend controlling a VAV unit,...

    How do you recommend controlling a VAV unit, where the unit must discharge around 55 to 60 deg F whenever its running if not by discharge air temp?

    Most equipment manufacturers (applied units, not...
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    1,154

    The main question is - are the VAV's change over?...

    The main question is - are the VAV's change over? Do they recognize (or do you tell them) when there's hot air in the duct vs cold air in the duct.

    A true VAV system is cooling air only. One...
  3. Thread: Wgx 9100

    by DreamCar
    Replies
    6
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    1,002

    Yes, configuring and commissioning.

    Yes, configuring and commissioning.
  4. Replies
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    1,095

    Up here in the great white north... On our...

    Up here in the great white north...

    On our MUA's you definitely need to not open heating wide all night. Open / close is fine, maintain a plenum temp of some kind at about 60 or 70.

    Forget...
  5. Thread: NCE Info

    by DreamCar
    Replies
    5
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    614

    Yes, it can have graphics on the "NAE" portion of...

    Yes, it can have graphics on the "NAE" portion of the NCE that display collected N2 data.
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    985

    Yes, this can be done, I can do this on my other...

    Yes, this can be done, I can do this on my other laptop. If you need more than one side loop, or want to put a UNT program into a VAV, there is I think 2 fields to change in one of the dbase files. ...
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    1,536

    I only use GPL for steam 3 way valves...

    I only use GPL for steam 3 way valves...
  8. Replies
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    899

    The N2 on board the McQuay chiller is of no use...

    The N2 on board the McQuay chiller is of no use for remote accesss, its purely for reading slave io boards. JCI made the OEM controllers for McQuay, so it had an N2 on it.

    Your best bet for...
  9. Thread: VMA1420

    by DreamCar
    Replies
    9
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    598

    Right you are, I should have checked before...

    Right you are, I should have checked before posting. It was late & I wasn't at my work laptop. Just lazy!

    This is however an open forum for discussion, and I for one would rather know the...
  10. Thread: VMA1420

    by DreamCar
    Replies
    9
    Views
    598

    If my recollection is sound (a big if...) you...

    If my recollection is sound (a big if...) you can't download a pressure dependant sequence into a VMA-1420.
  11. Replies
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    If you want the valve open at 100% at 25psi, 0%...

    If you want the valve open at 100% at 25psi, 0% at 10psi, just use a PI loop, with setpoint of 10, prop band of 15 (10+15 = 25psi full open).

    If you want more accurate control to a specific number...
  12. Thread: VMA1420

    by DreamCar
    Replies
    9
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    598

    I didn't think the CZA supported pressure...

    I didn't think the CZA supported pressure independant control. Haven't used it in a while though, so I'm not really sure.
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    2,199

    Try "State Transition Table" in Wikipedia. Its...

    Try "State Transition Table" in Wikipedia. Its the basis for the FEC programming, and if you're used to following a program from input - to logic - to output, this will be a real switch.
  14. I did a test setup once as a demo. Never...

    I did a test setup once as a demo. Never actually sold it though. It did work & I was able to read / write to the NAE. Schedules came up fairly nicely too. Any specific questions?
  15. Replies
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    2,315

    The NAE likely supplies all the data for either...

    The NAE likely supplies all the data for either the OWS or your remote laptop. Remote Access Software is not required, it just makes the process faster.

    Go to JCI public document site & search...
  16. Replies
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    2,298

    One PID or 2 doesn't change the rest of your...

    One PID or 2 doesn't change the rest of your sequencing, just how it tunes. You still need to do all the rest - ie make sure it doesn't spend too much time below say 10%, and open very slowly on...
  17. Replies
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    2,298

    If you have trouble tuning with a single PID loop...

    If you have trouble tuning with a single PID loop on both valves, try a pair of PID loops - one for each valve. Simply lock them at 0 or 100% according to your sequence. That way you get separate...
  18. Replies
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    That's the downside of most heat pump systems -...

    That's the downside of most heat pump systems - no air side economizer available. Interior zones, or server rooms etc need their compressorized cooling year round.
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    Absolutely right, the only thing that might want...

    Absolutely right, the only thing that might want an outdoor air lockout would be the spray pump to prevent it coming on in freezing weather when the sump is likely drained.

    Other than that, just...
  20. Replies
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    563

    Well, its probably the UNT or the current sensor....

    Well, its probably the UNT or the current sensor. UNT's typically have a default minimum on / off time, so if the current sensor flaked out for a second, the burner would likely turn off & stay off...
  21. Replies
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    563

    Any discharge temp sensor on the UNT? Could be...

    Any discharge temp sensor on the UNT? Could be cycling on a high limit if the sensor is bad (assuming it never actually gets any heat out of the burner).

    We've had some trouble with the UNT's...
  22. Replies
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    563

    you might want to verify that the controller is...

    you might want to verify that the controller is indeed turning the burner off. Try a pilot light in parallel with the call for heating. If the light stays on while the burner shuts off, its...
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    868

    If that's really all it is, just add an...

    If that's really all it is, just add an "activity" to any one of the 3 columns (I would use output control column). View logic of that activity, add your 2 float inputs, one enum output (off/on),...
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    Thanks! Will keep in mind.

    Thanks! Will keep in mind.
  25. Replies
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    962

    I have no experience with the varitrac, but could...

    I have no experience with the varitrac, but could it be a tube for your static pressure sensor is nfg, pinched, or fallen off the controller?
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