WaterFurnace Envision Hydronic (NSW) - Manual (Page 37)

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NSW INSTALLATION MANUAL
Reference Calculations
Legend and Notes
Heating Calculations:
LWT = EWT - HE
GPM x C*
Cooling Calculations:
LWT = EWT + HR
GPM x C*
HE = C* x GPM x (EWT - LWT) HR = C* x GPM x (LWT - EWT)
NOTE: * C = 500 for pure water, 485 for brine.
Abbreviations and Definitions
ELT = entering load fluid temperature to heat pump kW = kilowatts
SWPD = source coax water pressure drop EST = entering source fluid temperature to heat pump
LLT = leaving load fluid temperature from heat pump HE = heat extracted in MBTUH
PSI = pressure drop in pounds per square inch LST = leaving source fluid temperature from heat pump
LGPM = load flow in gallons per minute HC = total heating capacity in MBTUH
FT HD = pressure drop in feet of head COP = coefficient of performance, heating [HC/kW x 3.413]
LWPD = load coax water pressure drop EER = energy efficiency ratio, cooling
LWT = leaving water temperature TC = total cooling capacity in MBTUH
EWT = entering water temperature HR = heat rejected in MBTUH
Brine = water with a freeze inhibiting solution
Notes to Performance Data Tables
The following notes apply to all performance data tables:
• Three flow rates are shown for each unit. The lowest flow rate shown is used for geothermal open loop/well water
systems with a minimum of 50°F EST. The middle flow rate shown is the minimum geothermal closed loop flow rate.
The highest flow rate shown is optimum for geothermal closed loop systems and the suggested flow rate for boiler/
tower applications.
• Entering water temperatures below 40°F assumes 15% antifreeze solution.
• Interpolation between ELT, EST, and GPM data is permissible.
• Operation in the gray areas is not recommended.