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PUMP SELECTION
For the most efficient operation of the water heating system the circulating pump must be sized
correctly.
The pump should be installed on the inlet to the water heater especially where the system water
pressure is low.
Refer to the 'flow rate and pressure drop table' on page 13 for the minimum and maximum flow rates
for each model to determine the pressure loss through the water heater for the required temperature
rise and add this to the other system pressure losses when sizing the pump.
Note: The flow rate must never be below the minimum
stated in the Flow Rate and Pressure Drop table.
Where the water flow rate exceeds the maximum shown in
the Flow Rate and Pressure Drop table, a bypass with a
balancing valve must be installed to reduce the water flow
through the water heater (see diagram opposite).
For pump sizing where the water heating system
incorporates Rheem storage tanks, refer to the 'pump
selection and pipe size table' on page 13.
Intermittent pump operation
Where pump operation is intermittent, a remote thermostat must be fitted in the system and a pump
run on timer is required to remove residual heat from the water heater and prevent nuisance tripping of
the high limit switch. A run on timer is available as an optional kit (Rheem part No 56076874).
Flow Rate and Pressure Drop Table
Modulating (10
Model
l/sec
520
2.87
670
3.58
770
4.06
870
4.66
* Where marked as maximum water flow, the temperature rise will be greater than 10
Pipe Size and Pump Selection Table
Model
UPS
Series
B0520
32-80B
B0670
32-80B
32-80B
B0770
40-60/2B
32-80B
B0870
40-60/2B
INSTALLLATION
Max Flow Rate
°
C Rise)
kPa
6
10
14
22
Pump
Speed
TP Series
3
3
3
50-30/4B
2
3
1
50-30/4B
Max Flow Rate
°
On/Off (15
C Rise)
l/sec
kPa
1.91
3
2.39
4
2.71
6
3.11
8
Minimum Manifold Header Size (mm)
Branch
Size
1 Unit
1/4
1
32mm
32
1/2
1
40mm
40
2
50mm
50
1/2
1
40mm
40
2 ½
65mm
65
2
50mm
50
13
Min Flow Rate
°
(20
C Rise)
l/sec
1.43
1.79
2.03
2.33
°
°
C or 15
C as noted.
2 Units
3 Units
50
65
50
65
80
100
50
80
100
125
65
80
kPa
3
3
4
5
4 Units
80
80
100
80
150
100
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