How to prevent your solar hot water heater freezing in winter frosts
Simple steps you can take to help prevent freezing and frost damage to solar hot water heater collectors and solar hot water panels in winter
Burst solar hot water manifolds and split solar hot water panels are nearly always the result of freezing and frosts in winter and are extremely expensive to repair or replace. Parts may not be available for older models, and the original system manufacturers will refuse warranties when non-genuine parts are used for repairs. Therefore, if your collectors burst, you may be forced to replace the entire solar hot water system.
Typically, both tube and panel solar hot water collectors have frost protection. Evacuated tube systems will circulate water between the storage tank on the ground and the collector manifold on the roof when the water temperature in the collector manifold drops below 3°C. Flat panel tank-on-ground systems will circulate water between the storage tank 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 collectors if the water temperature in the collectors drops below 2°C. The collectors on flat panel tank-on-roof systems are filled with an antifreeze anti-boil fluid called glycol.
Why does freezing occur in solar hot water collectors?
Solar hot water collectors are filled with water. Without frost protection, the water in these systems will freeze with heavy frost. Freezing may occur because:
- The circulating pump has failed,
- A sensor on the roof is faulty,
- The solar controller is faulty,
- There are an insufficient number of frost protection valves on the collector panels,
- A non-return valve may have melted,
- The pipe work between the storage tank and collectors may be poorly insulated, or
- The glycol may be too diluted in the collector panels.
Freezing may also occur when homeowners believe that due to the pump vibrating, quietly making noise or it is hot, it must therefore be working. These ARE indicators that there is power going to the pump. However, they are also the same symptoms as a jammed or broken pump impeller and when the flow and return pipes are blocked.
Loss of power to the solar hot water control station and pump can also result in damaged solar hot water collectors.
There are some basic tests homeowners can do themselves. However, they are not 100% conclusive. To properly test a solar hot water system requires someone to climb on the roof and undertake a visual inspection and use of specialist equipment. Specialist equipment may also be required to test components at the tank on the ground. A specialist solar hot water repairer will have specialist equipment that can test flow rates, temperature settings and sensor operation.
Basic things owners can do to reduce the possibility of frozen solar hot water collectors
For electric boosted and gas boosted solar hot water heaters with the tank on the ground:
One month before winter and during the middle of winter, we recommend homeowners conduct the following basic tests:
- Check the weather to be certain that you will have at least three consecutive sunny days,
- Check that the power point for the solar controller is working. If the controller has no display, use a small appliance such as a hair dryer to test the power point,
- Check all electrical leads and sensors are correctly plugged in,
- Check your controller display for error codes and warning lights (some sensors plug into the bottom of the controller. If you have one of these models, ensure all sensors are plugged into the controller correctly). If 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 electric or gas booster. If you continuously have hot water for three consecutive days afterward, your solar pump, sensors and controller are working.
If you do not have hot water after one or more days, call a solar hot water expert for help.
For electric or gas boosted solar hot water heaters with the tank on the roof:
One month before winter and during the middle of winter, we recommend homeowners conduct the following basic tests:
- Check the weather to be certain that you will have at least three consecutive sunny days,
- Turn off the electric or gas booster. If you continuously have hot water for three consecutive days afterward, your solar hot water system is working. However, these systems should be inspected and serviced once every 5 years.
All of the tests owners can do are very basic and will not a guarantee that your solar hot water heater will not be damaged by frost. We service Apricus, SolarArk, Solahart, Rheem, Edwards, and Hills solar hot water systems.
Solar hot water heaters require a full service and inspection once every five years. Between services, these are simple steps solar hot water heater owners can take to help prevent frozen and frost damage to solar hot water heater collectors and solar hot water panels in winter.
