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  1. #1

    Confused Lack of flow can someone help!

    Hi is there anyone that can help with the following:

    The site i'm on has a chiller system, 2x Carrier 30RH 12.5KW which supplies 4x Trane Fan Coil Units 2.5KW in ticket kiosks which are all piped in parallel. The Fan coil units have only a three port valve on them. The problem that we are experiencing is that the last ticket booth on the run isn't acheiving temperatures which are as low as the other kiosks. the supply temp on the flow is 14C and the return is 18C which I feel would indicate a load? However, the supply air temp is only 19C whereas, in the other booths the temperatures on the supply air are about 14C.

    We have isolated the supply checked the flow pressure, checked correct operation of the three port valve, bled the coil and cleaned sediment from the system but, with no change in temperatures.

    We have had someone out and they suggested another pump on the system, but when I explained the above to them and asked if a pump would solve the problem they said "maybe". (not very convincing). The Pressure and flow seem ok and there are no additions to the system so surely it would hve been set up correctly in the first place and there would be no need for an extra pump?

    Can anyone give any suggestions or solutions to the problem of no flow, I would really appreciate any advice or suggestions. Many thanks.

  2. #2
    Join Date
    Jul 2001
    Location
    VA
    Posts
    2,801
    Shut off one of the other two, and evaluate the change in the problem child.......

    you may have a circuit setter issue. Make sure you are running the loop pressure to spec.
    ___________________________________________


  3. #3
    Join Date
    Jan 2008
    Location
    windy city
    Posts
    4,426
    check all your pd's, including the pump.verify valves& check strainers.like DPSwitch stated, isolate the 'working' coils, & then check your 'problem child'

  4. #4
    Thanks for your help so far I really appreciate it.
    I have looked on the system and found no strainers however, I have found a balancing valve on the return pipe which is fully open. Would it help if I reduced the balancing valve on the return?

    Also I have looked on the drawings and can't find the system pressure on the spec. Does anyone have an idea of what the pressure should be as it is currently 3bar? On the chillers itself however there is a prssure relief valve rated a 4bar. would I be right in thinking 3 bar is OK?

    Thanks very much.

  5. #5
    Join Date
    Aug 2006
    Location
    ohio
    Posts
    257
    What the heck is 3 bar?

  6. #6
    Join Date
    Jun 2005
    Location
    Ohio
    Posts
    1,720
    Quote Originally Posted by greyham View Post
    Hi is there anyone that can help with the following:

    The site i'm on has a chiller system, 2x Carrier 30RH 12.5KW which supplies 4x Trane Fan Coil Units 2.5KW in ticket kiosks which are all piped in parallel. The Fan coil units have only a three port valve on them. The problem that we are experiencing is that the last ticket booth on the run isn't acheiving temperatures which are as low as the other kiosks. the supply temp on the flow is 14C and the return is 18C which I feel would indicate a load? However, the supply air temp is only 19C whereas, in the other booths the temperatures on the supply air are about 14C.

    We have isolated the supply checked the flow pressure, checked correct operation of the three port valve, bled the coil and cleaned sediment from the system but, with no change in temperatures.

    We have had someone out and they suggested another pump on the system, but when I explained the above to them and asked if a pump would solve the problem they said "maybe". (not very convincing). The Pressure and flow seem ok and there are no additions to the system so surely it would hve been set up correctly in the first place and there would be no need for an extra pump?

    Can anyone give any suggestions or solutions to the problem of no flow, I would really appreciate any advice or suggestions. Many thanks.
    Were all three 3-way valves in the "100% to coil position" when you took those readings? Is there a balancing valve in each 3-way bypass line? It should be set for 85% of coil design flow.
    Anybody test the actual pump GPM verses design? That's the beginning.
    How about pump actual amperage verses FLA? Did you have to throttle the pump discharge to keep amperage down?
    I didn't convert *C to *F, but how is "the temp on the flow(CHW?) 14C " when the supply air on the 2 good CHW coils is 14C?
    Interesting problem though.
    jogas

  7. #7
    Join Date
    Jul 2008
    Location
    Washington, DC
    Posts
    1,582
    Check to be sure the fan coil is piped correctly in regards to supply and return. This can actually make quite a difference, in part due to how the condensation loads on the coil.

  8. #8
    Join Date
    Aug 2008
    Posts
    129
    Quote Originally Posted by michael26 View Post
    What the heck is 3 bar?
    1 bar = 14.5037738 pounds per square inch

  9. #9
    Join Date
    Jan 2008
    Location
    windy city
    Posts
    4,426
    Quote Originally Posted by michael26 View Post
    What the heck is 3 bar?
    the third bar visited on a pub crawl

  10. #10
    Join Date
    Mar 2007
    Location
    Netherlands
    Posts
    33
    Did you check the airflow of the fancoil units and the number of rows of the coils? Did you also check the waterflow trough each fancoil? It seems to me that there is no balance. Install 4 balancing valves from TA and measure the water flow.

  11. #11
    Join Date
    May 2008
    Location
    Jax Fl.
    Posts
    1,943
    Turn off all the flow through the other kiosks and see if you get satisfactory performance. If not you have a blocked coil.

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