9221017B
Grundfos Pump
The pump adjuster should normally be left at maximum
(3) but in some cases it is permissible to adjust the pump
to a lower setting (2). See diagram 4.1.
To use diagram 4.1 start with the required heating
system load.
In the example shown the maximum boiler output has
been chosen, 17.6kW.
Draw a horizontal line from the required system
differential temperature axis to intersect the curve.
In the example 110C has been chosen, shown .
At the point of intersection draw a vertical line to cross
the pump curve. From this point draw a further
horizontal line to determine the available pump head.
In the example 19kPa is available. A greater pump head
can be achieved by choosing a higher system differential
temperature, up to a maximum of 50kPa at a system
differential of 170C. The system must be designed such
that the available pump head is not exceeded.
If the heating system load is less than 13.2kW then it is
permissible to adjust the pump
setting to (2), shown .
This results in an available pump head of 21kPa.
This is the maximum that can be achieved with the pump
at this setting.
Glow-worm Wilo Pump
The pump adjuster should normally be left at maximum
(2) but in some cases it is permissible to adjust to a lower
setting (1), see diagram 4.1a.
To use diagram 4.1a start with the required heating
system load.
In the example shown the maximum boiler output has
been chosen, 17.6kW.
Draw a horizontal line from the required system
differential temperature axis to intersect the curve.
In the example 11oC has been chosen, shown .
At the point of intersection draw a vertical line to cross
the pump curve. From this point draw a further
horizontal line to determine the available head. In the
example 19kPa is available. A greater pump head can be
achieved by choosing a higher system differential
temperature, up to a maximum of 50kPa at a system
differential of 17oC. The system must be designed such
that the available pump head is not exceeded.
If the heating system load is less than 13.3kW then it is
permissible to adjust the pump setting to (1),
shown . This results in an available pump
head of 41kPa. This is the maximum that can be
achieved with the pump at this setting.
4 H e a t i n g S y s t e m
4.1 General Notes
The boiler is for use in sealed water systems only.
4.2 Safety Valve
The safety valve is an integral part of the boiler and it
cannot be adjusted.
4.3 Pressure Gauge
A pressure gauge is incorporated into the boiler to
indicate the system pressure.
4.4 Pump
The circulation pump is integral with the boiler.
The remaining circulating pressure head available from
the boiler is shown in diagram 4.1, Grundfos or 4.1a
Wilo.
4.5 Expansion Vessel
The boiler has an integral expansion vessel with a
capacity of 8Litres, with a charge pressure of 0.075MPa.
The maximum heating system water content using the
fitted expansion vessel ranges from 119Litres with a cold
fill pressure of 0.07MPa, to 98Litres with a cold fill
pressure of 0.105MPa. If, due to a high static head, the
cold fill pressure is higher, then the expansion vessel
pre-fill pressure must be increased, and the maximum
system volume decreased.
4.6 Flow Rate
A valve must be incorporated in the main flow or return
of the system, valve “A” shown in the flow in
diagram 4.2. This valve must be lockable and positioned
so that inadvertent closure or unauthorised interference is
not possible. The design differential can be between
11oC and 17oC, dependent on the system resistance and
the available pump head.
