Eco-King HWB-299, Installation And Service Manual

Page: 35 / 124

E93.1801EN171 HWB installation manual 35
9.1.3 W
ATER HEATER RESISTANCE GRAPH
HWB-499
Minimum required pump head.
To prevent calcification of the heat exchanger, the speed of the water needs to be high. The design flow of the
system should be at a delta T of 27 °F (15 °C) at high fire. To calculate the minimum required pump head, take
the resistance of the water heater and add the resistance of the piping and tank to make a good design.
Normally, an extra 6.6 feet of head (2 m.WC) is sufficient to overcome the resistance of the pipe and tank.
Water heater
ΔT = 27 °F (15 °C)
at flow rate
min. required head
for water heater
min. required head for in-
stallation
+ 6.6 feet.WC / +2 m.WC
[gpm] [m3/h] [ft.WC] [m.WC] [ft.WC] [m.WC]
HWB-299 19.70 4.47 19.5 5.94 26.1 7.94
HWB-399 26.44 6.01 16.9 5.15 23.5 7.15
HWB-499 31.66 7.19 15.3 4.67 21.9 6.67
0
5
10
15
20
25
30
0 5 10 15 20 25 30 35 40 45 50
pr
es
uur
e dr
op [
ft o
f he
ad]
Flowrate [gallons (US)/minute]
Resistance graph HWB-499
ΔT=20 °F ΔT=27 °F