sy24inst2 - The Initiative Group

Rendamax
Type ∆T 22 K Pump data
R301
R302
R303
R304
R305**
R306**
R307**
Nominal
flow
rate
Boilerresistance
Grundfos
pump
type
Pump
speed
Head
at
Qnom.
Available
head at
Qnom.
Max.*
power consumption
m 3 /h kPa UPS kPa kPa W
2.72
3.51
4.52
5.48
7.25
9.05
10.85
17.0
23.5
30.0
30.0
20.0
23.0
32.0
25-80
25-80
32-80
32-80
32-120F
32-120F
32-120F
3
3
3
3
3
3
3
66
58
52
45
75
65
52
49.0
34.5
22.0
15.0
55.0
42.0
20.0
245
245
245
245
380
380
380
Table 8
Water flow rate and pump data R300
* The maximum power consumption of the pump is given for pump speed 3. The optimum operating point in
relation to efficiency and minimum power consumption can be determined from the related pump curve
** 3-phase pump available as an option.
The optional primary pump has been sized to have an optimum duty when∆T = 22 K. When running
at ∆T’s less than this the pump size should be checked to ensure suitability.
The water flow rate can be adjusted with the aid of the built-in 3-speed pump control. The water
flow rate can be measured by making a ∆P measurement via the filling and drainage valve in the
supply and return pipe of the unit. The measured head can be compared with the boiler resistance
(table 8). At full capacity the water flow rate can be very accurately compared with the ∆T, measured
across the flow and return of the boiler.
The unit has a standard pump control. When the boiler is enabled, the pump is switched on. When
the enable signal is removed, the pump will continue to run for several minutes. This run on time
is adjustable. The standard time is two minutes.
y
When the system includes air heaters (ventilation, air treatment), it is usually desirable to have a
small ∆T over these components. Because of this, the quantity of water flowing through the total
secondary circuit is usually greater than that flowing through the boiler units.
The low velocity header must be dimensioned such that the water speed does not exceed 0.5 m/s.
In this case the diameter of the header must be calculated for the water volume flowing through
the secondary circuit. When the water volume flowing through the secondary circuit is great er
than that flowing through the primary circuit, a mixed temperature will exist which is lower than
the desired temperature of the supply from the appliance. The regulation system reacts to this
and opens the control devices (valves, etc.). Usually the supply temperature from the boiler(s)
must be adjusted to obtain the desired temperature in the connected circuits.
For additional energy savings an optional speed controlled pump is available for the R300 series.
For details of this, consult your supplier.
22 Doc586/50CV22C