Page 381 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 6 Hot water systems

low standing heat loss and keep CO emissions to a minimum, in line with the
2
Regulations. The new thicknesses are:
● Part L1A (new build and replacement cylinders) have 50 mm insulation
● Part L1B (replacement only cylinders) have 35 mm insulation.
Cylinder insulation jackets are also available for uninsulated cylinders. They
are made from fibreglass insulation with a PVC jacket. They are tied with a
lace at the top and kept in place by either aluminium bands or plastic straps.

Grades of storage cylinder
Open vented hot water storage cylinders are manufactured to BS 1566–1:
2002 – Copper Indirect Cylinders for Domestic Purposes. Open Vented Copper
Cylinders. Requirements and Test Methods.
BS 1566 specifies three grades of cylinder, with each grade indicating the
pressure the cylinder will withstand. The grades of cylinder are:

1 Grade 1: 25 metres head
2 Grade 2: 15 metres head
3 Grade 3: 10 metres head.

25 m

15 m
10 m

 Table 6.9 Common sizes of
open vented hot water storage
cylinders
Grade 1 Grade 2 Grade 3
2.5 bar operating 1.5 bar operating 1.0 bar operating Size Capacity
pressure pressure pressure
3.65 bar test 2.20 bar test 1.45 bar test 900 mm × 350 mm 74 litres
pressure pressure pressure 900 mm × 400 mm 98 litres
p Figure 6.14 The grades of cylinder and their maximum working pressures 1050 mm × 400 mm 116 litres
900 mm × 450 mm 120 litres
Storage cylinder sizes and capacities 1050 mm × 450 mm 144 litres
Open vented hot water storage cylinders are available in a wide range of sizes 1200 mm × 450 mm 166 litres
and capacities. The more common sizes are listed in Table 6.9. 1500 mm × 450 mm 210 litres

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