Rinnai E75CN - Manual (Page 19)

Installation & Servicing Instructions Rinnai E-Series
19
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.
When using more than one boiler in an installation please refer to the cascade
installation instructions.
The boiler is designed to be used on pressurized heating systems only.
pump index lines graph 1
NOTICE
i
NOTICE
i
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12
Q [gallons/min]
PSI
UPS 20-48 UPS 20-58 Resistance OSS1 Resistance OSS2
32.3
27.7
23.0
18.5
13.8
9.2
4.6
0
Feet of head
Resistance E75C UPS 20-48
25% UPS 20-58
100% Resistance E110C