Solar System Trouble Shooting

VM solar heating systems are renowned for their quality, longevity and simplicity. A system that has been sized correctly in the design process should be very low maintenance; requiring service only once every few years.


NOTE: The information presented in this page is for guidance only - no part of this may be used for any agreement, whether express or implied, or to form any contract. THERMO TECHNOLOGIES reserves the right to change specifications and prices without prior notice.


An 'F' reading on controller LCD display
  • Loose connections on sensor leads
  • Faulty sensor
  • Collector sensor at maximum
  • Check sensor wires for connection
  • Replace sensor
  • No action required
Pump will not run
  • Power wiring faulty
  • Pump rotor damaged
  • The pump control selector P is in manual 'OFF' position
  • TC incorrectly set
  • TC and DT not satisfied
  • Check wiring and fuses
  • See pump manufacturers instructions
  • Check controller unit and return pump control P to automatic mode 'AUT'
  • Reset to 25°C
  • No action required
Pump runs continuously
  • Collector temperature is below TF temperature
  • Loose connection or faulty sensor on the collector
  • Collector temperature at maximum
  • No action required TF flashes
  • Check connections and sensor wires
  • No action required
No circulation in system
  • Pump isolating valves closed
  • Automatic air-vent closed
  • Air lock at pressure relief valve
  • Air lock in the system
  • Non-return valve jammed
  • Pump is not running
  • System in stagnation
  • Open valves
  • Open aut. air-vent and check condition - replace if necessary
  • Twist cap at pressure relief valve and vent air
  • Flush the solar loop 
  • Free valve or replace
  • See above
  • Wait until system reaches normal operating conditions
Pressure drops in system
  • Leak at manifold
  • Leak in system
  • Drain/filling valve not closed
  • Aut. air-vent passing water
  • Faulty pressure relief valve
  • Damaged expansion vessel causes pressure fluctuation and relief valve to open
  • Check manifold compression fetting for leaks tighten if necessary
  • Check all joints
  • Close fully
  • Clean or replace if necessary
  • Replace
  • Replace
  • Pump does not run
  • Prolonged period of low hot water consumption
  • See above
  • Divert heat to heat sink
Performance loss
  • Broken tubes
  • Damaged insulation
  • Build up of lime stone around heat exchanger tube condenser
  • Replace broken tubes (because of diode function of tube replacement does not have to be done immedi-ately)
  • Replace damaged parts
  • Drain and clean system thoroughly

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