Solar Thermal Systems - Looking After Them is Simple Yet Crucial

It is commonly known that solar thermal systems are low in maintenance when compared with other heating systems. Despite this, it is recommended that basic maintenance is completed to help the system work efficiently.

Solar thermal systems use the free energy from the sun to heat hot water while they can help to reduce your energy bills by a considerable amount. Along with this, maintenance is simple and straightforward.

Many systems come with self-cleaning glass which makes things easier but there is more that can be done to help increase the efficiency. However, it’s important to remember that when it comes to maintenance, it should be completed by a competent individual such as an engineer. Furthermore, prior to any work being completed, the collectors should be covered and then the system should be left to cool down while the electrical supply to the system should be isolated.

Installers will need to check a range of components within the system. The collectors should be checked to make sure that all fixings are secure and tightened where required. Along with this, the condition of the collectors should also be reviewed to ensure that there is no damage to the glazing while the glass should be cleaner to ensure that all dirt is removed. 

The pipe connections should also be checked to identify any potential leaks while the pipe insulation should be checked to see if there are any pipes exposed or whether any of the insulation is damaged, with all damaged insulation being replaced. The final thing to consider when it comes to the collectors is the sensor as this should be located correctly and fitted securely.

Next up, the system pipework needs to be looked at and a visual inspection should be carried out. This will help to spot any leaks while the PRV operation should be tested by rotating the plastic cap on the valve to operate. Now the condition of the pipe insulation should be checked for damage and where necessary, it should be replaced.

It is also worth checking the pressure in the expansion vessel by monitoring it and this can be achieved through three simple steps.

• Close the isolation valve on the expansion vessel connection
• Open the small drain cock on the connector and drain off a small amount of solar fluid into a clean container (keep this aside to test, please see below)
• Check the air charge in the vessel
• Adjust or re-pressurise the vessel as necessary to achieve the correct pressure (this may require putting additional solar fluid into the system)

When it comes to testing the expansion vessel pressure, it’s important that a small amount of solar fluid is extracted in order for tests to be completed on it. A refractometer is used to identify the levels and concentration of antifreeze as well as the level of protection on offer. Next up it’s important to use suitable litmus indicator strips to test the acidity ph value. Should these tests indicate that the fluid is not suitable then it will need to be replaced.

Once all of the checks have been carried out, you should also check the hot water storage cylinder that is fed by the solar thermal system. This should be serviced in line with the manufacturer’s recommendations such as ensuring it is serviced annually. The cylinder should also be checked to ensure that it is positioned correctly and fitted correctly.

Once all of the above tests have been completed, it is then possible to restart the system and bring it back into operation. Below is a summary of steps that you can use to ensure that the system is restarted correctly.

• Check the cold system pressure, via the press gauge, and make sure it is correct for static height of the system – top-up or re-fill as required
• After reconnecting the power supply to the controls, check that the settings on the solar controller are correct and then operate the override on the controller, checking that the solar pump starts
• With the solar pump running, check the volume flow rate and reset as necessary. It is important to ensure that the correct system volume flow rate is also set in the solar pump station.

If you ensure that your solar thermal system is well maintained then you’ll be able to rely on it for many years to come. This will ensure that it remains problem-free and provides you with the heat and hot water that you need.