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DESIGN
SYSTEM DETAILS
Extent of the
components
included with
the BMA OV SOL
Fill and flush valve,
check valve and
temperature gauge
assembly
Appliance
control board
Solar pump
BMA
OV SOL
Figure 1.13
PRV
discharge
pipe
5 amp
junction box
Flow
(from panel)
Return
(to panel)
Solar panel (collector)
SC - Collector flow temperature sensor
0
20
100
120
40
80
60
Pressure
gauge
SR - return
temperature/
flow sensor
SZ - Thermal store
solar zone sensor
Solar coil
Solar
control board
Expansion
vessel
Solar System
A schematic layout of a solar system
incorporating a BoilerMate A-Class OV SOL
appliance is shown above.
As can be seen, the BoilerMate A-Class OV SOL
appliance includes almost all the equipment
normally provided in a solar pumping station.
On this basis, the flow and return pipework
from the solar panel(s) (collectors) should be
run directly from the panel to the BoilerMate
A-Class OV SOL.
A 6 bar pressure relief (safety) valve will be
required on the solar return to the solar collector.
To allow future maintenance/testing, its location
shall be accessible. The discharge pipe shall
be of a rigid and non-deformable constitution
ie. metal. No valves should be fitted in the
pipework between the solar collector and the
pressure relief (safety) valve. The discharge
from the pressure relief (safety) valve shall
terminate in a position where the discharge of
steam/scalding water will not cause any injuries
or harm to persons or property. A suitably sized,
high temperature receptacle, an internal gulley or
at low level externally, are all normally considered
acceptable termination points. However, a high
level termination from walls or on roofs is not
normally considered acceptable because of the
possible harm to people below.
A suitable solar expansion vessel will also be
required and a 15mm connection with pressure
gauge is provided on the top of the appliance.
The vessel shall be sized and the initial filling
pressure established in accordance with an
approved method such as set out in Appendix
D of the Solar Heating, Design and Installation
Guide produced by the Domestic Building
Services Panel of the Chartered Institute of
Building Services Engineers.
However, the chart opposite provides an
indication of the likely vessel size and fill
pressures required when using a flat plate
collectors and a 6 bar safety valve (allowing 1.0
bar over pressure).
The collector flow temperature sensor (SC) is
wired into the BoilerMate OV SOL complete
with 2.5 metres of cable (2 x 0.75mm
2
double
insulated). However, dependant on the location
of the solar panel(s) this may need extending
by the installer on site (up to a maximum of
50 metres). It is recommended that the cable
is jointed in a 5amp junction box fitted in the
roof space adjacent to the panel(s). The sensor
(6mm diameter) will need to be fitted in the
solar panel or flow pipe from the solar panel as
near to the panel as possible.
The solar panel(s), expansion vessel, pressure
Expansion Vessel Sizing Chart
System Height
(metres)
2.5
5.0
10.0
System Volume
(litres)/Maximum
Collector Area (m
2
)
Vessel size/pre-charge pressure/initial fill pressure
(litres/bar/bar)
<10/5
18/1.3/1.6
18/1.5/1.8
18/2.0/2.3
20/7.5
25/1.3/1.6
25/1.5/1.8
35/2.0/2.3
30/12.5
35/1.3/1.6
35/1.5/1.8
40/2.0/2.3
50/15
40/1.3/1.6
50/1.5/1.8
50/2.0/2.3
Note: System height refers to the difference in height from the top of the collector
to the expansion vessel.
