Reference Calculations; Legends And Notes - Johnson Controls RC Series Engineering Manual

RC SERIES ENGINEERING GUIDE

Reference Calculations

Heating Calculations:
HE
LWT = EWT -
GPM x 500
HC
LAT = EAT +
CFM x 1.08
TH = HC + HW

Legends and Notes

ABBREVIATIONS AND DEFINITIONS:
CFM = airflow, cubic feet/minute
EWT = entering water temperature, Fahrenheit
GPM = water flow in gallons/minute
WPD = water pressure drop, PSI and feet of water
EAT = entering air temperature, Fahrenheit
(dry bulb/wet bulb)
HC = air heating capacity, MBTUH
TC = total cooling capacity, MBTUH
SC = sensible cooling capacity, MBTUH
KW = total power unit input, kilowatts
HR = total heat of rejection, MBTUH
Notes (Refer to Capacity Data tables)
• Capacity ratings are based on 80°F DB / 67°F WB EAT for cooling and 70°F DB EAT for heating.
• 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 EWT. 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.
• The desuperheater numbers are based on a flow rate of 0.4 GPM/ton of rated capacity with an EWT of 90°F.
• Entering water temperatures below 40°F assumes 15% antifreeze solution.
• For non-standard EAT conditions, apply the appropriate correction factors on (Refer to Correction Factor Tables).
• Interpolation between EWT, GPM and CFM data is permissible.
Cooling Calculations:
HR
LWT = EWT +
GPM x 500
SC
LAT (DB) = EAT (DB) -
CFM x 1.08
LC = TC - SC
S/T =
SC
TC
34
HE = total heat of extraction, MBTUH
HW = desuperheater capacity, MBTUH
EER = Energy Efficient Ratio
= BTU output/Watt input
COP = Coefficient of Performance
= BTU output/BTU input
LWT = leaving water temperature, °F
LAT = leaving air temperature, °F
TH = total heating capacity, MBTUH
LC = latent cooling capacity, MBTUH
S/T = sensible to total cooling ratio