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Calculated Example 1
The example is for a 1/2” diameter temperature relief valve with a discharge pipe (D2)
having 4 x 22 mm elbows and a length of 7 m from the tundish to the point of discharge.
The maximum resistance allowed for a straight length of 22 mm copper discharge pipe (D2)
from a 1/2” diameter temperature relief valve is 9.0 m.
Subtract the resistance for 4 x no 22 mm elbows at 0.8 m each = 3.2 m. Therefore, the
maximum permitted length equates to: 5.8 m. This 5.8 m is less than the actual length of
7m, therefore, calculate the next largest size.
Maximum resistance allowed for a straight length of 28mm pipe (D2) from a 1/2” diameter
temperature relief valve equates to: 18 m. Subtract the resistance for 4 No 28 mm elbows
at 1.0 each = 4 m.
Therefore the maximum permitted length equates to: 14m. As the actual length is 7m, a 28
mm diameter copper pipe will be satisfactory.
5. INSTALLATION - ELECTRICAL
WARNING:
This equipment and pipework must be earthed. All electrical wiring must
be carried out by a competent person and in accordance with current regulations.
5.1. Sheathed heating elements
Two parallel 1.2kW 230v 50Hz sheathed heating elements are pre fitted to the cylinder.
5.2. Wiring
The power supply to the product must be via a double pole isolator switch or controller,
having contact separation of at least 3 mm, to comply with BS 6141 and must be fully
earthed. In case of an electric problem, check that the wiring follows:
a) The earth wire is connected to the cylinder terminal marked with the earth symbol.
b) The live wire is connected to the high temperature cut-out terminal.
c) The neutral wire is connected to the high temperature cut-out terminal.
WARNING:
Do not switch on the elecricity supply until instructed to do so in the
commissioning procedure and once the product is full of water.
