Table of Contents
Advertisement
Minimum required pump head.
To prevent calcification of the heat exchanger, the water flow rate needs to be high. The design flow of the sys-
tem should be at a delta T of 16.5 / 12.5 °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 2 m.WC of head is sufficient to overcome the resistance of the pipes and tank.
Water heater
at flow
ΔT = 16.5 °C
rate
[m
EFW 85
4.26
EFW 105
5.08
EFW 125
6.23
EFW 155
7.58
Pump: maximum electric power
General
-
The inrush current of a conventional pump is approximately 2½ x its nominal current.
The maximum allowed switch current of the burner controller is 2 A.
-
So the maximum current of the connected pumps is 2 A. Nominal.
-
Your supplier can offer two different pumps
Pump number
Pump type
P1
Grundfos UPMXL GEO 25-125N 180
P2
Wilo Stratos Para Z 25/1-12
Pump P1 meets this requirement. The pump main voltage connection can be directly connected to connections
6-7-PE of the high voltage connection terminal. The PWM cable must be connected to 18-19 of the low voltage
connection terminal.
Pump P2 has a high inrush current. Therefore it is not allowed to connect the main voltage connection of pump
P2 directly to the boiler terminals. Connect the pump main voltage connection directly to the external (wall
socket e.g.) main voltage. The PWM cable must be connected to 18-19 of the low voltage connection terminal.
min. required head
for water heater
3
/h]
[m.WC]
5.45
5.65
5.54
5.14
E93.1804.014
min. required head for
installation: +2 m.WC
[m.WC]
7.45
7.65
7.54
7.14
39
Advertisement
Table of Contents
