How to stop solar hot water systems freezing in Canberra’s winter frosts
What you should do to help stop freezing and frost damage to solar hot water system manifolds and solar hot water panels in winter
Cracked and leaking solar hot water system manifolds and solar hot water panels are almost always a result of heavy frosts and temperatures below 0°C in winter.
Evacuated tube and flat panel solar hot water collectors have frost protection systems. Evacuated tube systems will circulate water between the storage cylinder on the ground and the roof-mounted collector manifold, when the water temperature in the collector manifold drops below 3°C. Flat panel cylinder-on-ground systems will circulate water between the storage cylinder on the ground and the roof-mounted collectors when the water temperature in the collectors drops below 3°C, and will dump water from the collector panels if the water temperature in them drops below 2°C. The collectors on flat panel cylinder-on-roof systems are filled with an antifreeze anti-boil fluid called glycol.
Cracked and leaking solar hot water system manifolds and solar hot water panels are extremely expensive to repair or replace. New parts may be unavailable for some brands, and the original equipment manufacturer may not be willing to provide warranties if non-genuine spare parts are used to replace damaged parts. Because of this hot water system owners may be required to replace the entire solar hot water heater.
Why does freezing occur in evacuated tube and flat panel solar hot water systems?
Loss of power to the solar controller contributes to freezing of solar hot water collectors. Freezing also occurs in solar hot water heater collectors because:
- There are an insufficient number of anti-frost valves on the collector panels,
- The circulating pump has failed,
- A roof sensor on the collectors is damaged,
- The solar controller is faulty,
- A non-return valve has melted,
- The flow and return pipes between the storage cylinder and collectors may be poorly insulated, or
- The glycol has been diluted in the solar hot water system.
Frost damage also occurs when solar hot water system owners mistakenly believe that when a pump is vibrating, emitting a soft humming sound, or is hot, it must be working. These are also signs that the pump may be jammed or broken, or the solar flow and return pipes are blocked.
There are some things owners can do themselves. However, they do not guarantee 100% protection against frost damage. Specialist equipment in the hands of an experienced solar hot water technician is the best course. The technician will test the solar components on the roof and at the storage cylinder. The technician will test operational temperatures, flow rates, and check for signs of previous damage to sensors, valves and glycol levels.
What can owners can do themselves, to reduce the possibility of frost damage to solar hot water collectors?
Gas and electric boosted with storage cylinder-on-the ground solar hot water systems:
One month before winter and during the middle of winter, owners should do the following things:
- Use your weather app to check that there are at least three consecutive sunny days to run a thorough test on the solar hot water system,
- Test the power point for the solar controller is working. If the solar controller has no display, a small appliance such as a hair dryer can be used to check the power point,
- Inspect all electrical leads and sensors to ensure they are correctly plugged in,
- Inspect your solar controller for error codes and warning lights. If you have checked all leads and plugs and you still have an error code or warning light, you will need to call a solar hot water expert to have the system serviced.
- Turn off the power supply to the electric or gas booster.
If after 3 consecutive days you have had a consistent supply of hot water, it is an indication that the solar pump, sensors and solar controller are working.
If you do not have a consistent supply of hot water after one or more days, call a solar hot water repairer for help.
Gas and electric boosted with storage cylinder-on-the-roof solar hot water systems:
One month before winter and during the middle of winter, owners should conduct the following tests:
- Use your weather app to check that there are at least three consecutive sunny days to run a thorough test on the solar hot water system,
- Turn the electric or gas supply off to the booster. If you have a consistent supply of hot water for 3 consecutive days after, your solar hot water system is working.
Remember, the above tests are rudimentary and are not a guarantee that your frost protection systems are working. If you need peace of mind, we can help. Our servicing can help prevent frost damage in winter to Apricus, SolarArk, Solahart, Rheem, Edwards, and Hills solar hot water systems.
All hot water systems require a thorough service once every 5 years. Servicing solar hot water systems on a regular basis will help stop freezing and frost damage to the system’s manifold and solar hot water panels in winter.
