Preventative planned maintenance is prudent on all solar thermal systems to maintain efficiency and increase reliability.

Expensive repairs can often be avoided or risks reduced if a system is well maintained.


High temperatures break down and damage the antifreeze.
Turns the antifreeze from an Alkaline with a pH of 8-9 to pH 7 or below.
Acidic can cause corrosion which will in turn can perforate the pipework, the solar panel itself or the cylinder coil.
Cause expansion vessels to corrode and diaphragms to fail.
Panels or evacuated tube internal pipework can be blocked.

Leaks and airlocks can cause.

  • Poor reliability
  • Reduced efficiency
  • Property damage
  • Pumps burning out

The solar systems that tend to run most reliably are those that:

  • Rarely overheat
  • Have heat pipe evacuated tubes
  • Have temperature mixing valves fitted. (and allow the water temperature to be stored at 70-80 degrees C)
    Include a heat dump facility
  • Drain back systems
  • That are monitored and regularly serviced

The solar systems that tend to have the most problems are those that:

  • Are over powered systems. (too larger panel area)
  • Residents who use little hot water
  • Residents that are often away in the summer months
  • Direct flow evacuated tubes
  • Badly designed or installed systems
  • Neglected and un-monitored systems.

During a service we would normally:

  1. Visual Inspection of the tubes or flat plate collector.
  2. Visually Inspect fixings.
  3. Checking glycol (antifreeze) concentration.
  4. Checking glycol (antifreeze) pH.
  5. Operate air removal devices.
  6. Check Controller settings.
  7. Set pump speed and flow rate.
  8. Check Expansion Vessel pressure.
  9. Check system pressure.
  10. Operate pressure relief valves.
  11. Clean panels if practical for 1engineer without using ladders.
  12. Record hours run.
  13. Investigate if the system has overheated.
  14. Check for leaks.
  15. Explanation of solar controls to customer and how best to top up the heat when required.

Recommended service intervals.

There is no exact frequency that we would recommend.
It would depend on the systems design, how much you monitor it and how much hot water you use.
We would advise on site what we consider to be reasonable service intervals between.
Please contact us if you would like your system to be inspected.