Loop Sizing
This properties tab contains the fields that are necessary to calculate plant loop flow rates and equipment capacities when auto sizing. This information is initially used by components that use water for heating or cooling such as hot or chilled water coils to calculate their maximum water flow rates. These flow rates are then summed for use in calculating the Plant Loop flow rates.
Loop Sizing Method
This field controls how concurrence issues impact the plant loop flow rate. There are two options:
o Block - The cooling plant capacity is equal to the sum of the highest block load as simulated of the airside cooling coils as well as demand loads assigned to the cooling plant.
o Peak - The cooling plant capacity is equal to the sum of the airside cooling coil capacities or demand loads assigned to the cooling plant.
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Min & Max: N/A
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Typical Range: N/A
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Units: N/A
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Block Sizing Timestep
This is the number of timesteps used in a moving average to determine the design flow rate for plant sizing. This allows using a broader average over time.
Input Considerations: If you want to size a plant based on a larger timestep (e.g. 1 hour versus 15 minute time step increments), you would enter in a value that would be greater than 1 here. A good example would be wanting to size a plant based on a 1 hour average versus a timestep for simulation which is 15 minutes. A number of 4 would be entered (15 x 4 = 60 minutes) to size the plant based on one hour.
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Min & Max: 1 to 60
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Typical Range: 1 to 4
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Units: N/A
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Temperatures
Loop Temperature Difference
The design temperature rise (for cooling or condenser loops) or fall (for heating loops) across the demand side of the loop. This temperature difference is used by component models to determine flow rates required to meet design capacities.
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Input Consideration: Larger values lead to smaller design flow rates.
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Default values: Cooling loop: 10°F; Heating loop: 10°F; Mixed loop: 10°F; Condenser loop: 10°F
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Min & Max: -999 to 999
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Typical Range: -999 to 999
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Units: °F; °C
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Design Exit Temperature
The water temperature at the exit of the supply side of the plant loop. This is the temperature of the water supplied to the inlet of chilled or hot water coils and other equipment that places loads on a plant loop.
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Input Considerations: A higher or lower than normal temperature may impact equipment performance.
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Default values: Cooling loop: 44°F; Condenser loop: 95°F; Mixed loop: 90°F; Heating loop: 180°F
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Min & Max: -999 to 999
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Typical Range: 0 to 200
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Units: °F; °C
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Maximum Temperature
Defines the maximum allowable temperature for the loop.
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Default values: from template
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Min & Max: -999 to 999
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Typical Range: 0 to 200
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Units: °F; °C
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Minimum Temperature
Defines the minimum allowable temperature for the loop.
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Default values: from template
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Min & Max: -999 to 999
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Typical Range: -30 to 200
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Units: °F; °C
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Loop Sizing Factor
This is the factor to over or undersize the capacity of the loop. This is also more commonly known as a safety factor.
Default values from template
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Min & Max: 0 to 1000
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Typical Range: 100 to 200
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Units: %
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Fluid and Flow Rates
Fluid Type
This field determines the type of fluid for the loop: Water, Ethylene Glycol or Propylene Glycol. If Ethylene Glycol or Propylene Glycol is selected, the Glycol Concentration field becomes available. Ethylene Glycol or Propylene Glycol is used as an anti-freeze.
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Default values: water
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Min & Max: N/A
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Typical Range: N/A
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Units: N/A
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Glycol Concentration
Only appears when Ethylene Glycol or Propylene Glycol is selected for the fluid type. As an example, a mixture of 60% ethylene glycol and 40% water freezes at -49 degrees F.
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Default values: 30%
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Min & Max: 0 to 100
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Typical Range: 20 to 40
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Units: %
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Ice Tank Sizing
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Default values: 10 hr
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Min & Max: N/A
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Typical Range: N/A
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Units: hours
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