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  1. #1
    Join Date
    Mar 2004
    Location
    Columbus Ohio
    Posts
    328
    I have to control a couple of large fan coil units with
    hot water and chilled water valves in a plant where the
    chilled water temp is 34 degrees. So modulating valve control is needed. The cust. wants to keep it as simple
    as possible. Was looking at Tranes ddc package but its a
    bit pricey. Im told the honeywell T7350C prog. stats can
    handle this with 2 to 10 vdc outputs. They dont desire set
    back. They just want something simple and reliable. I can
    choose any control and compatable valves I want. Thanks in
    advance for your thoughts

  2. #2
    Join Date
    May 2002
    Posts
    9,564
    You were considering Trane DDC than went to programmable?

    Do you have a budget to work with?
    Economizers?
    Any consideration in the future for expansion?

  3. #3
    Join Date
    Mar 2004
    Location
    Columbus Ohio
    Posts
    328
    There is no economizer,just manual fresh air, future
    expansion is unlikley, I have approx $3000 to work with
    Tranes zn529 package would work nicley and I was also
    going to look into Honeywells XL15 controllers. But if
    I could accomplish this with a simple thermostat with a
    2 to 10 vdc or 4 to 20ma output to the valves and fan
    contacts perhaps I can cut the cost. It was the T7350M1008
    stat which has (2) 4 to 20ma outputs for about $270 ea

  4. #4
    Join Date
    Jul 2002
    Posts
    889
    Location is a consideration. If these come into an occupied mode and the space is warm they could blow SUPER cold for a long time, seriously upsetting anyone near them. With a programmable controller you can put in a supply air sensor and put in a low temp limit plus other things you want.

  5. #5
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    Perhaps Johnson's System 350 controls will do what you want and save you on the cost at the same time.


  6. #6
    Join Date
    Mar 2004
    Location
    Columbus Ohio
    Posts
    328
    Incontrol, I was assuming if this thermostat had 4 to 20ma
    outputs then it would have a supply air sensor and modulate
    valve so air isnt super cold. They will supply a inspection
    area which will be constantly occupied. Norm, Ive only used the 350 series for water loop contrl
    staging boilers,towers, didnt know they had modulating
    control mods. But the thought of the 15A mounted on the
    wall (for s.p. adj) doest sound good
    I thought since I dont need communicating and scheduling
    capability...why pay for it. They want to keep it simple so
    Im not sure they would go for the T7350 since its programmable with 10 buttons etc...
    Was looking at some Viconics stuff that might fit the bill
    Thanks for the replies

  7. #7
    Join Date
    Apr 2004
    Posts
    566
    you might consider stats fron tcs basys controls they have stand alone stats with 0-10 outputs and can also be connected to there front end if desired in future. stuff works good

  8. #8
    Join Date
    Mar 2004
    Location
    Columbus Ohio
    Posts
    328
    Thanks Bobby,The SZ1060 series controls look good for this
    application. Just might be the ticket if the price is right

  9. #9
    Join Date
    Jul 2001
    Location
    Canada
    Posts
    1,813
    Have done quite a few setups like this in a local plant. They wanted to control the temperature in mixing rooms , rooms had a constant exshaust.

    Used TCS/Basys SZ1143a controller , has (1) 4-20 output , duct sensor on the exshaust duct and controlled KMC VEP series 3 way valves off the ex air temperature.

    Also did humidity control in 1 room for them using duct humidity sensor to control dehumidifier with a SZ1143a.

    Price was within your noted $ budget with the 3 way valve included.

    [Edited by Control Man on 02-13-2005 at 05:16 PM]

  10. #10

    ControlMan

    I thought you were a Barber Coleman guy, Can't you use a PEM or a Microzone and be under the 3,000.00 limit with a lot more room for adjustments than an off the shelf controller can give you.

  11. #11
    Join Date
    Jul 2001
    Location
    Canada
    Posts
    1,813
    After nearly 30 years I am Not MARRIED to any one control / controller I use what is needed to keep my customers happy.

    MZII or PEM is higher $ plus you would require PSI and a laptop everytime they need to adjust the setpoint. better off with CP 8161 if it had to be BC.

    SZ1143 you use the keypad ( access code )if they want SOFTWARE REV PRO is cheap and readily available.

    Plant I put the TCS in has 4 major DDC systems + 5 INDUSTRIAL control systems , plant operators like the TCS for the application its used for.


  12. #12
    Ok,

    I guess I assumed that you were or worked for an Invensys dealer, where the cost would then be compatible with the job, there are remote set points that go along with these controls but that also drives the price up.

    Sounds you might be looking for something low end like floating control or something, there are several of these to choose from.

  13. #13
    Join Date
    Mar 2004
    Location
    Columbus Ohio
    Posts
    328
    My customer wants digital control,they just wanted to avoid
    an elaborate sys. that requires a pc to change a set point
    or software etc... They dont have a front end, most of the
    systems have pnuematic controls. I checkd out the Baysys
    SZ1162 (I think) and it is just what Im looking for.
    A nonprogrammable digital stat with (2) 4 to 20 m.a. outputs,fan control,and several config. points so I can set limits & setpoints of discharge air,keypadlock etc. My cost for this control is 1/5 of the trane control. I think
    its going to work great Thanks alot guys

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