With all sensor wires disconnected and the control switch in the "automatic" position,
jumper the two terminals marked "Collector" (or "COLL," etc.) (Figure 4-1). The solar
loop pump (and water loop pump, if used) should come on.
Operation by the
With the collector sensor terminals shorted, jumper the sensor terminals marked
"Storage" (or "STOR," etc.). The pump(s) should go off.
To test the high limit function, first determine the brand and type of differential
thermostat controlling the system. Most controls are 10K, that is their sensors have
10,000 ohms resistance at 77F. If you have any doubt about this, refer to t h e
system's operation and maintenance manual. If one does not exist, remove a
sensor, give it time to come to room temperature, and measure its resistance with
Controls manufactured by Heliotrope General and Johnson Controls are not likely to
be 10K. Table 4-4 contains information on currently available controls.
Determine the high limit setting of the control from Table 4-4, the control labeling, or
the setting of the control's high limit adjustment dial. (-This dial is usually on a
potentiometer, sometimes called a "pot.") (Figure 4-2)
4.3 TROUBLESHOOTING OPERATIONS