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PUMP AND CONTROLLER
SOLAR CONTROLLER
The solar controller's function is to turn the solar pump on and off to enable the solar collectors to transfer heated
water to the storage cylinder when there is capacity in the cylinder to store more energy and when the temperature
difference between the cylinder and collector temperatures is suitable for energy collection.
A differential temperature between solar collector (hot sensor) and tank (cold sensor) of greater than 6°C causes
the pump to be switched on. When differential falls to below 2°C the pump switches off.
When the cold temperature sensor reaches 65°C the pump is switched off. This prevent water that is too hot
returning from the solar collectors to the storage cylinder and activating the P&TR valve.
The other function of the controller is to pump water through the collectors when there are frost conditions to
prevent the collector from freezing. When the hot temperature sensor (in collector) drops below 4°C the pump
activates to prevent freezing. When this temperature reaches 8°C the pump stops. This option is selected via the
menu screens on the controller. This function should be selected when the installation may be exposed to frost.
Refer to Commercial Controller Manual 15401117 for details on how to access these functions.
Location of Cold Temperature Sensor
Stainless Steel Storage Cylinder
Cold
Sensor
Lead
Resistance of Temperature Sensor Leads
Both temperature sensor leads have approximately the following resistances. This information can be used to
verify performance of the leads. Should hot sensor lead be extended, use equivalent cable joined to existing
connection point. DO NOT cut cable near thermistor, as it is specifically designed for high operating temperatures.
Use of lower quality cable can result in false temperature readings. To ensure correct operation,
connect extra cable and test that complete assembly delivers correct resistance readings relative
IMPORTANT
to temperature (as per table below). Incorrect temperature readings due to under performing
cable extension can result in poor solar performance, lack of frost protection and void warranty.
Temperature (°C)
0
10
20
30
40
50
Rinnai
Resistance (Ohms)
32500
19800
12500
8000
5250
3500
26
Vitreous Enamel Storage Cylinder
Temperature (°C)
60
70
80
90
100
Cold
Sensor
Lead
Resistance (Ohms)
2500
1600
1250
900
700
DD FP Solar Pre Heat System OIM
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