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  1. LowDeltaTSolver

    Primary Secondary Chilled Water System

    A tertiary pump system is not required and makes the system pumping control more complex. The current DP sensor can be effectively used to control the secondary pump VFD if the current DP sensors set point can be reset based on Chilled Water Control Valve positions. At least one valve position...
  2. LowDeltaTSolver

    Primary/Secondary chilled water system pumping - variable primary - variable secondary

    Variable primary pumping requires a very sophisticated and expensive controls and highly trained chiller plant operators. Sequencing chillers on and off is very complicated with a variable primary only system The variable primary - variable secondary flow system (VPF-VSF)system in the article...
  3. LowDeltaTSolver

    Insufficient CHW water flow in existing pipe

    Were any temporary strainers installed and not removed for this circuit?
  4. LowDeltaTSolver

    Primary/Secondary chilled water system pumping - variable primary - variable secondary

    Yes I designed a Variable Primary Flow (VPF)/Variable Secondary Flow (VSF) flow system for an existing University Campus Chilled water system. The design approach was published in ASHRAE Journal October 2014 Technical Feature "Simplified Chiller Sequencing for a Primary/Secondary Variable...
  5. LowDeltaTSolver

    What if there is no Decoupler line in CHW system?

    PS Very good explanation of how a decoupled primary/secondary piping system arrange works. However, you limited the system operation to a traditional constant primary flow (CPF) and a variable secondary flow (VSF) system. You can also have a variable primary flow (VPF) and a variable...
  6. LowDeltaTSolver

    Low Delta T

    SDTH SDTH Question: Why should the operator switch on additional chiller?.. He can simply run a primary pump to balance the flows. Response: The primary objective of a chilled water system should be to maintain the distribution supply temperature at or below the design temperature at all...
  7. LowDeltaTSolver

    Low Delta T

    To better understand the Low Delta T issue and possible solutionS, additional information is needed on your application. What is the piping configuration? Primary/Secondary or Primary What type of pumping is used? Constant Primary Flow Pumping (CPF) Variable Primary Flow Pumping (VPF)...
  8. LowDeltaTSolver

    Variable Primary Flow CHW and chiller interaction

    marcoh See 16-Jan-15 comments If the approach indicated in the ASHRAE Journal October 2014 Article " Simplified Chiller Sequencing" is used, No costly flow meters or differential pressure sensors are required to control staging of chillers. The indicated approach only requires four...
  9. LowDeltaTSolver

    Make Up water demand

    ZDR1985, First of all, an air washer is not a swamp cooler. Swap coolers rely on evaporative cooling and are used in dry arid areas to reduce the supply air temperature. Leaving air temperature will be near saturation. Air washers deliver chilled water directly to the air washer spray...
  10. LowDeltaTSolver

    Check Valve in Chilled Water Decoupler Bridge

    BronYrAur The hospital may want to consider a Variable Primary Flow/Variable Secondary Flow (VPF-VSF) system to to mitigate the Low Delta T issues. See ASHRAE Journal October 2014 Article "Simplified Chiller Sequencing"...
  11. LowDeltaTSolver

    Variable Primary Flow CHW and chiller interaction

    ELoyRD, The B&G Technical Manual TEH-910A discusses many issue and or concerns associated with automatic operation of a Variable Primary Flow (VPF) system. Are you concerned that the primary pump will continue to run when the chiller shuts down and the chiller automatic control isolation valve...
  12. LowDeltaTSolver

    Chiller Optimization

    See AHSRAE Journal October 2014 Article titled "Simplified Chiller Sequencing." Link The article describes a chiller sequencing approach for a primary/secondary chilled water system that is being used for a university campus chilled water distribution system. The control approach minimizes...

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