Changing the Solar Thermal Heat Transfer Fluid vs Topping It Up

Grant Funding, Heating, Installations, Renewable Energy, Repairs, Servicing, Solar Thermal

Why do I need Heat Transfer Fluid?

Solar Thermal systems use heat transfer fluids to collect, store and transfer heat from solar collectors.  These fluids play a critical role in the efficiency and longevity of solar thermal systems.  We recommend and use glycol – water mixtures in the systems we maintain.  This mixture lowers the freezing point and raises the boiling point, protecting the system in a wide range of temperatures.  As part of our Solar Thermal Maintenance Plan we change your heat transfer fluid every 5 years at no additional cost.

Why are you recommending a flush, clean and refill rather than just topping the system up?

Changing the heat transfer fluid in a solar thermal system is a critical maintenance task that ensures the system operates efficiently and has a longer life span.  We recommend the fluid is changed approx every 5 years to:

1. Prevent fluid degradation

The fluid degrades over time due to high temperatures and continuous cycling through the system.  Typically the fluid becomes sticky and oderous.  Simply ‘topping up’ the existing fluid would merely contaminate the new fluid.  Breakdown of the fluid can produce acids, which can corrode system components.  

2. Maintaining Freeze Protection

For the systems we maintain which have glycol-water mixtures, the glycol provides freeze protection, over time the glycol can break down or become diluted.  If the glycol concentration drops, the fluid may freeze in cold weather potentially damaging pipes and collectors

3. Preventing Corrosion and Scale Buildup

Heat transfer fluids often contain corrosion and anti-scale inhibitors that protect the systems internal components.  These inhibiators are designed to prevent the metal parts of the system from corroding which can lead to component failure.  Anti-scaling agents prevent mineral deposits from forming on the inner surfaces of the collectors and pipes which can obstruct flow and reduce efficiency

4. Ensuring Optimal Heat Transfer

Clean and fresh heat transfer fluid maintains its properties better than old, degraded fluid.  Fresh fluid ensures that the system can effectively absorb and transfer heat from the solar collectors to the cylinder to your taps! Good maintenance ultimately maintains consistent system performance, ensuring reliable operation and energy savings.

5. Extending System Lifespan

Regular maintenance, including changing the heat transfer fluid can significantly extend the lifespan of the solar thermal system.  By preventing/minimising corrosion, scaling and other issues the components such as a pump could last longer and reduce the likelihood of costly repair bills 

6. Safety Considerations

Using fresh heat transfer fluid can also enhance the safety of the solar thermal system.  Degraded fluid might not effectively manage the systems thermal load, leading to overheating and potential safety hazards.  




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