Technical data

Page 18
1.0 DESIGN
1.3 SYSTEM DETAILS
Heating System
Expansion Vessel Requirements
The BoilerMate expansion vessel is pre-charged to 1.0 bar. The maximum water content
of the heating system (boiler + radiators + connecting pipework + primary coil but
NOT store volume) must not be greater than those shown in the table below.
A fi gure of 4.5 litres/kW of installed radiator capacity can be used for a preliminary
assessment of the water content of the heating system.
The values presented in the table are based on a maximum boiler fl ow temperature of
93
o
C. The expansion vessel must be suitable to accommodate the change in volume
of the water in the system when heated from 10
o
C to 110
o
C as specifi ed in BS 5449:
1990 clause 16.2.
The primary heating coil and pipework volumes are shown in the table in 1.2 Technical
Data.
In normal circumstances an initial vessel and system charge pressure of 1 bar is suitable
for most domestic purposes.
The minimum system pressure should not be less than the static head plus 0.5 bar
i.e. the height of the highest point in the system above the expansion vessel plus a
margin of 0.5 bar.
If the system volume is greater than that shown in the table at the selected operating
conditions then an additional expansion vessel must be fi tted.
12 Litre Vessel i.e. BMA 120/140/180
Maximum Recommended Heating System Volumes
Safety valve setting (bar) 3.0
Vessel charge pressure (bar) 0.5 1.0 1.5
Initial system pressure (bar) 0.5 1.0 1.5 1.0 1.5 2.0 1.5 2.0
Maximum permitted system
volume (litres)
140 80 40 110 60 27 70 35
25 Litre Vessel i.e. BMA 200/220
Maximum Recommended Heating System Volumes
Safety valve setting (bar) 3.0
Vessel charge pressure (bar) 0.5 1.0 1.5
Initial system pressure (bar) 0.5 1.0 1.5 1.0 1.5 2.0 1.5 2.0
Maximum permitted system
volume (litres)
270 160 85 200 115 50 140 65