50 – Part 7: Troubleshooting
Part 7: Troubleshooting – 51
Nature of trouble
Possible cause
Service
Pump does not operate (even
though there is solar radiation and
the tank is cold).
No power to pump.
Check controller and pump wiring.
Controller improperly set.
Check program - Refer to pump station
manual “Control parameter” section.
Sensor out of position.
Check position of all sensors.
Sensor defective.
Check sensor resistance - Refer to controller
manual “Tips for Fault Localization” section.
Pump defective.
Replace pump.
Pump operates intermittently.
Normal when weather changes.
None.
Sensors connected to wrong terminals.
Check sensor connections - Refer to
controller manual “Installation” section.
Improper system “switch-on” or “switch-off” temperature.
Check sensor resistance - Refer to controller
manual “Control parameter” section.
Sensor out of position.
Secure sensor properly.
System pressure too high.
Filling pressure too high.
Adjust system pressure to 50 psi (3.5 bar).
Expansion tank initial pressure too high.
Isolate and adjust expansion tank to 40 psi
(2.8 bar).
Expansion tank too small.
Properly size and replace expansion tank.
System pressure too low.
Propylene glycol leak in system.
Check system for leaks and repair.
Expansion tank too small (release of propylene glycol from
relief valve).
Properly size and replace expansion tank.
Controller improperly set or sensor defective.
Check program - Refer to controller manual
“Control parameter” section.
Temperature differential between
collector and storage tank too
high.
Controller improperly set.
Check program - Refer to controller manual
“Control parameter” section.
Sensor out of position.
Secure sensor properly.
No power to pump.
Check controller and pump wiring.
Air or impurities present in system.
Properly commission system, purge all air.
Pump defective.
Replace pump.
Pump operates at night.
Normal on very warm nights.
None.
Check valve open or dirty.
Check position of check valves, clean or
replace if necessary.
Controller defective.
Replace controller.
Storage tank cools down rapidly.
Consumption higher than design for system.
Reduce rate of hot water use.
Check valve open or dirty.
Check position of check valves, clean or
replace if necessary.
Insulation defective or inadequate.
Add, repair, or replace pipe insulation as
needed.
