10
10.0 Determining the Cold Fill Pressure
Determining the Cold Fill Pressure
The cold fill pressure is critical to the
correct operation of any pressurisation
unit and associated system. This
pressure needs to be calculated from
the static pressure of the system
(measured height in metres from the
base of pressurisation unit to the top
of the highest part of the heating
system, divided by 10 to convert to bar
pressure), and an allowance for venting
and vapour pressure. Therefore, the
cold fill pressure for a system with a
maximum operating temperature up
to 90°C, can be calculated as per the
example below:
Static Pressure
0.8 bar
(Height of 8.0m
divided by 10)
Venting Allowance 0.3 bar
(Allowance from
table below)
Vapour Pressure
0.0 bar
(Allowance from
table below)
Cold Fill Pressure 1.1 bar
(Sum of the above)
Venting and Vapour Pressure Allowances
Venting Allowance
0.3
Allowance to ensure system can be correctly vented
Vapour Pressure
Allowance
0.0
Max operating temperature up to 90°C
0.2
Max operating temperature 90°C to 95°C
0.5
Max operating temperature 95°C to 100°C
0.8
Max operating temperature 100°C to 105°C
1.2
Max operating temperature 105°C to 110°C
1.6
Max operating temperature 110°C to 115°C
2.0
Max operating temperature 115°C to 120°C
