Rinnai E75CN Installation & Servicing Instructions Manual page 23

i
NOTICE
14
E75C
E110C
12
10
8
6
4
2
0
0
UPS 20-48 (25%)
UPS 20-48
pump index lines
The boiler has a self-adjusting and self-protecting control system for the load and the
pump capacity. By this means the temperature difference between the supply and return
water is checked and controlled.
If the installation resistance is over the stated value; the load will be adjusted until
an acceptable temperature difference between supply and return water has been
obtained. If, after this, the temperature difference is still not acceptable then the boiler
will switch off and wait until an acceptable temperature has arisen.
If an unacceptable temperature is detected, the control will repeatedly try to achieve
water flow over the boiler. If not the boiler will switch off.
The electrical side of an external circulation pump (fig. 6, pos. 8) can be connected
to the Control Tower. This pump thus switches simultaneously to the boiler pump.
The maximum absorbed current consumption of the external circulation pump may
not exceed 120V, 2 Amp. If a pump with a larger current draw is required an isolation
relay must be used. See the Rinnai Boiler Applications Manual for further information.
The extra external pump must be selected according the installation resistance and
required flow.
As standard the boiler is provided with a water filter in the return pipe of the boiler, so
that debris of the central heating water is prevented from affecting the boiler.
The boiler is designed to be used on pressurized heating systems only.
2 4
UPS 20-58 (100%)
UPS 20-58
6 8
Q [gallons/min]
Resistance E75C
Resistance OSS1
32.3
27.7
23.0
18.5
13.8
9.2
4.6
0
10 12
Resistance E110C
Resistance OSS2
graph 1
23