10
Henrad CC FF
- Installation
GENERAL
4
SEALED SYSTEM REQUIREMENTS - Central Heating - continued
5. Filling the system
Fill the system through a temporary hose connection
from a draw-off tap supplied from a service pipe under
mains pressure. Where the mains pressure is
excessive a pressure reducing valve shall be used to
facilitate filling.
The following fittings shall form a permanent part of
the filling system:
A double non-return valve with at least 1 isolation
valve, which is used as a temporary connection to fill
the system from the mains, after which it should be
disconnected and left with the installation.
Proceed with the following:
•
Thoroughly flush out the whole of the system
with cold water before fitting the boiler.
•
Fill and vent the system until the pressure gauge
registers 1.5 bar (22 lb/in
2
). Examine for leaks.
•
Release water from the system until a pressure
of 1 bar (15 lb/in
2
) is reached. To avoid getting
debris on the valve seat, do not use the safety
valve to do this.
•
Light the boiler and heat the system to the
maximum working temperature. Examine for
leaks.
•
Turn off the boiler and drain the system while
still hot.
•
Refill and vent the system.
•
Re-pressurise the system to the desired charge
pressure (see the table below).
6. Size of expansion vessel
For the system water expansion to be contained
by the 8-litre expansion vessel fitted to the boiler
the cold system volume must not exceed:
119 litres when pressurised to 0.5 bar (cold)
107 litres when pressurised to 0.7 bar (cold)
91 litres when pressurised to 1.0 bar (cold)
If the pressure exceeds 2.65 bar when the boiler
is up to temperature with all radiators in use then
an additional expansion vessel MUST be
installed on the return pipework.
For expansion volumes see the table below.
Guidance on vessel sizing is given below and
also in BS 7074:1 and BS 5449.
Vessel sizing / Expansion volumes
System charge pressure (bar)
0.5
0.7
1.0
Safety valve setting (bar)
3.0
Vessel pre-charge pressure (bar)
0.5
0.7
1.0
System volume litres
Volume of expansion vessel in
addition to 8-litre unit fitted to boiler
75
None
None
None
100
None
None
0.8
125
0.4
1.3
3.0
150
2.1
3.1
5.1
175
3.8
4.1
7.3
200
5.4
6.8
9.5
225
7.1
8.7
11.7
250
8.8
10.5
13.9
275
10.6
12.4
16.1
300
12.2
14.2
18.4
Multiply this factor by system volume and
deduct 8 litres to obtain size of additional
0.067
0.074
0.088
vessel for other system volumes.
Summary of Contents for CC 100 FF
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