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5.3 Discharge Pipe Sizing Example
This example shows how to select pipe diameter for a given discharge pipe.
For this example we will assume we are using a G½ temperature relief valve and require 4 elbows in
the discharge pipe run. The length of the pipe run from tundish to point of discharge is 7 metres.
Begin by calculating whether 22mm pipe would be sufficient
Consult Table 3 and look up the maximum resistance allowed for this pipe size (9 metres)
Consult Table 3 and look up the resistance of an elbow in this pipe size (0.8 m) As we have 4 el-
bows or bends, multiply (0.8m * 4m) = 3.2m
Subtract the resistance of the elbows from the maximum resistance (9m—3.2m) = 5.8m.
Is your length of pipe run less than or equal to the maximum permissible resistance for this pipe run?
6.0 Installation - Electrical Requirements
WARNING: This water heater must be earthed
The water heater is fitted with a control thermostat as shown in figure 6. It is essential that the en-
ergy source to the water heater is under the control of this device.
Figure 6—Thermostat Control
The water heater may be optionally fitted with an electrical immersion heater. Ensure that any elec-
tric immersion heater is fitted with a high limit and control thermostat.
Where an immersion heater is fitted, the following information is relevant.
Disconnect the electrical supply before removing the terminal cover. Installation must be in accor-
dance with the current I.E.E. Wiring Regulations.
The electricity supply should be fused to protect the immersion heater circuit and it should be possi-
ble to isolate it via a double pole isolating switch with a contact separation of at least 3mm in both
poles.
