Advertisement
DESIGN
Heating System
Open Vented Heating Systems
The layout of a typical open vented 'Y Plan' heating system is shown in fi gure 8. The
BoilerMate BP is equally suitable for 'S' and 'W' plan heating system layouts.
The fl ow pipe from the boiler should rise continuously up to the vent pipe to facilitate
venting. The heating circuit is taken directly from the boiler and is piped in the
conventional manner.
The F & E cistern supplied with the thermal store can be fi tted remotely up to 6m above
the base of the BoilerMate BP. If this cistern is used for the central heating as shown
in fi gure 8, then the water level in the F&E cistern should be at least 250mm above
the highest point on the system including the radiators and must be high enough to
provide the minimum head required by the boiler being used.
Sealed Heating Systems
The layout of a typical sealed 'Y Plan' heating system is shown in fi gure 9. The BoilerMate
BP is equally suitable for 'S' and 'W' plan heating system layouts. A boiler used in a
sealed heating system must be suitable for this application i.e. must be fi tted with an
overheat cut-out thermostat.
It is recommended that the F&E cistern (for the store) is fi tted at a high level in the
same cupboard as the BoilerMate BP. However it can be fi tted remotely up to 6m
above the base of the BoilerMate BP.
The F&E cistern overfl ow/warning pipe should be installed in a material suitable for a
heating system feed and expansion cistern in accordance with BS5449.
There shall be no permanent connection to the mains water supply for fi lling the
system even through a non-return valve without the approval of the Local Water
Authority. An approved fi lling loop is required with for fi lling the system, which should
be disconnected after commissioning the system. This should be located adjacent
to the boiler along with a suitable expansion vessel, pressure gauge, pressure relief
valve.
The table below can be used for sizing the heating system expansion vessel. The water
content of the primary heat exchanger is listed in table 1 and a fi gure of 4.5 l/kW of
installed radiator capacity can be used for a preliminary assessment of the water
content of the heating system.
Expansion Vessel Requirements
Safety valve setting
(bar)
Vessel charge
pressure (bar)
Initial system
0.5
pressure (bar)
Total System
Volume (l)
25
2.1
50
4.2
75
6.3
100
8.4
125
10.4
150
12.5
3.0
0.5
1.0
1.0
1.5
2.0
1.0
1.5
Expansion Vessel Volume (l)
3.5
6.5
13.7
2.7
4.7
7.0
12.9 27.5
5.4
9.5
10.5 19.4 41.3
8.2
14.2 30.9 11.7 24.8
14.0 25.9 55.1 10.9
19.0 41.2 15.6 33.1
17.5 32.4 68.9 13.6
23.7 51.5 19.5 41.3
21.0 38.8 82.6 16.3
28.5 61.8 23.4 49.6
The expansion vessel requirements shown in
table below are based on a maximum boiler
fl ow temperature of 93°C. The expansion vessel
must be suitable to accommodate the change
in volume of the water in the system when
heated from 10°C to 110°C a sspecifi ed in BS
5449:1990clause 16.2.
The minimum system pressure should not be
less than the static head plus 0.5bar i.e. the
height of the highest point in the system above
the expansion vessel plus a margin of 0.5 bar.
1.5
2.0
1.5
2.0
10.3
3.9
8.3
20.6
7.8
16.5
Page 14
Advertisement
