Powrmatic CP series User Manual

18
Appendix A
Calculation Of Flue System Equivalent Resistance
The pressure resistance of the flue system (Pr) can be calculated from
Pr = 1.5 * [(PFF*H/D+SRF)Qm/Wm2]
Where Pr = Pressure resistance of the flue system in pa
PRF = Pipe Friction Factor
H = Effective flue height in m
D = Internal Diameter of flue in m
SRF = Sum of individual resistance factors
Qm= Mean Density of the column of exhaust gas in kg/m3
Wm = Mean exhaust gas velocity in m/s
PRF
Can be calculated from
PRF = 0.118*(0.21147/D0.4)
Where D = Internal Diameter of flue in m
SRF
Typical resistance factors for individual components are as follows
Segmented 90° bend 0.5
45° Elbow 0.4
Cowl 1.0
Qm
Qm = 97000/(300*Tm)
Where the mean temperature of the column of exhaust gas (Tm) can be calculated from
Tm = 288+((Te-TL)/0.2)*(0.18)
Where Te is the exhaust gas temperature in °C
TL is the external air temperature in °C
Wm
Wm = M/(A*Qm)
Where A is the cross sectional area of the flue in m2
M is the exhaust gas mass flow in kg/s which is as follows for the various units
CP 100 0.018 CP 500 0.125 CP 1500 0.3
CP 150 0.027 CP 600 0.14 CP 2000 0.4
CP 200 0.035 CP 700 0.145
CP 300 0.050 CP 800 0.16
CP 400 0.080 CP 1000 0.2

Powrmatic CP series Specifications

General

Brand	Powrmatic
Model	CP series
Category	Gas Heater
Language	English