7. Sealed System
The system must comply with requirements of BS6798 and
BS5449.
The appliance must not be operated without the system being
full of water and correctly pressurised.
The pressure relief valve will operate at 3 bar. The discharge pipe
must be directed away from any electric's or from where it might
be hazard.
All connections in the system must withstand a pressure of up to
3 bar.
The expansion vessel, to BS4814, has a capacity of 10 litres
charged to 0.5 bar, which is suitable for a static head of 5 metres.
A schraeder type valve allows the pressure to be increased if the
static head is greater than 5 metres. Refer to BS 7074:1, BS5449
and Table 9 for a guide to the available system capacity. If the
expansion vessel fails then it must be replaced with the
designated spare part.
The maximum system design pressure is 1.5 bar. If the pressure
is above 2.6 bar when at maximum temperature then another
expansion vessel must be fitted as near to the appliance as
possible in the return pipe.
A filling loop is fitted to the appliance. Refer to Fig 8.
The system and the appliance must be properly vented.
Repeated venting loses water from the system and usually
indicates that there is a leak.
An adjustable by-pass is fitted to the appliance. Refer to Fig 9.
The pump is set at maximum and must be adjusted to suit the
system load
It is NOT suitable for direct water supply.
Do not connect to a direct cylinder.
The SBi can be connected to any indirect cylinder, i.e unvented or
thermal store, all the benefits of a "dry loft" and mains pressure
hot water can be realised. Refer to a separate leaflet or contact
Worcester Heat Systems Technical Helpline. 0990 266241.
8. Domestic Hot Water
7. Sealed System
8
Fig. 5. System layout if using built - in diverter valve.
Fig. 6. System layout if using external diverter valve.
RV
LV
LV
RV
RV
RV
LV
LV
INDIRECT
CYLINDER
APPLIANCE
Refer to fig.1.
Appliance
Water
Flow
Diagram
Heating Return
Heating Flow
Safety Discharge
Cylinder Return
Hot Water Flow
BS
Stop Valve Fixed Cylinder Type
Mains Cold Water
Radiator Valve - Flow
RV
Lockshield Valve - Return LV
Note:
A drain cock
should be fitted
at the lowest
point of the
heating circuit
and beneath
the appliance
RV
LV
LV
RV
RV
RV
LV
LV
INDIRECT
CYLINDER
APPLIANCE
Refer to fig.1.
Appliance
Water
Flow
Diagram
Heating Return
Heating Flow
Safety Discharge
Cylinder Return
Hot W
ater Flow
BS
Stop Valve Fixed Cylinder Type
Mains Cold Water
Radiator Valve - Flow
RV
Lockshield Valve - Return LV
Note:
A drain cock
should be fitted
at the lowest
point of the
heating circuit
and beneath
the appliance
Diverter
Valve
IMPORTANT
For Details of
the wiring
requirements
for the system
controls,
please refer to
the SBi System
Wiring Guide
and the
Instructions
supplied with
the Built-in
Mid-Position
Valve.
IMPORTANT
For Details of
the wiring
requirements
for the system
controls,
please refer to
the SBi system
wiring guide.
