Engineering Design Guide
HBH SERIES
Heat Controller, Inc.
3
Reference Calculations
BTUH = BTU (British Thermal Unit) per hour
CFM
=
airfl ow, cubic feet/minute
COP
=
coeffi cient of performance = BTUH output/BTUH input
DB = dry bulb temperature (°F)
EAT = entering air temperature, Fahrenheit (dry bulb/wet bulb)
EER
=
energy
effi ciency ratio = BTUH output/Watt input
MPT = male pipe thread
ESP = external static pressure (inches w.g.)
EWT = entering water temperature
GPM =
water
fl ow in U.S. gallons/minute
HE = total heat of extraction, BTUH
HC = air heating capacity, BTUH
HR = total heat of rejection, BTUH
HWC = hot water generator (desuperheater) capacity, Mbtuh
FPT = female pipe thread
KW = total power unit input, kilowatts
LAT = leaving air temperature, °F
LC = latent cooling capacity, BTUH
LWT = leaving water temperature, °F
MBTUH = 1000 BTU per hour
S/T = sensible to total cooling ratio
SC = sensible cooling capacity, BTUH
TC = total cooling capacity, BTUH
WB = wet bulb temperature (°F)
WPD = waterside pressure drop (psi & ft. of hd.)
Conversion Table - to convert inch-pound (English) to S-I (Metric)
Legend and Glossary of Abbreviations
Selection Procedure
Air Flow
Water Flow
Ext Static Pressure
Water Pressure Drop
Airflow (L/s) = CFM x 0.472
Water Flow (L/s) = gpm x 0.0631
ESP (Pa) = ESP (in of wg) x 249
PD (kPa) = PD (ft of hd) x 2.99
LWT = EWT -
HE
GPM x 500
LAT = EAT +
HC
CFM x1.08
LWT = EWT +
HR
GPM x 500
LAT (DB) = EAT (DB) -
SC
CFM x1.08
LC = TC - SC
S/T =
SC
TC
Heating
Cooling
