Selection Procedure - Heat Controller HEV Series Engineering Design Manual

Design Guide
Engineering Design Guide

Selection Procedure

Reference Calculations
Heating
HE
LWT = EWT -
GPM x 500
HC
LAT = EAT +
CFM x1.08
Hot Water Generator capacities (HWC) are based on potable water  ow rate of 0.4 gpm per nominal equipment ton and 90°F
entering potable water temperature.
Legend and Glossary of Abbreviations
BTUH= BTU( British Thermal Unit) per hour
CFM= air ow, cubic feet/minute
COP= coef cient of performance = BTUH output/BTUH input
DB= dry bulb temperature (°F)
EAT= entering air temperature, Fahrenheit (dry bulb/wet bulb)
EER= energy ef ciency ratio = BTUH output/Watt input
EPT= external pipe thread
ESP= external static pressure (inches w.g.)
EWT= entering water temperature
GPM= water  ow in U.S. gallons/minute
HE= total heat of extraction, BTUH
HC= air heating capacity, BTUH
HR= total heat of rejection, BTUH
Conversion Table - to convert inch-pound (English) to SI (Metric)
Air Flow
Airflow (L/s) = CFM x 0.472
UPFLOW
Left Return Air
Piping End
HEV-HEH SEriES
Cooling
HR
LWT = EWT +
GPM x 500
SC
LAT (DB) = EAT (DB) -
CFM x1.08
Water Flow
Water Flow (L/s) = gpm x 0.0631
Right Return Air
HEV/H SERIES
LC = TC - SC
SC
S/T =
TC
HWC= hot water generator (desuperheater) capacity, Mbtuh
IPT= internal 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.)
Ext Static Pressure
ESP (Pa) = ESP (in of wg) x 249
LEFT RETURN AIR
Left Return Air
Piping End
Back Discharge
RIGHT RETURN AIR
Piping End
Right Return Air
Piping End
Back Discharge
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Water Pressure Drop
PD (kPa) = PD (ft of hd) x 2.99
Piping End
Left Return Air
Piping End
Side Discharge
Right Return Air
Piping End
Side Discharge