Frost protection for solar and heat pump hot water systems
Solar hot water systems
If you live in an area that experiences temperatures below four degrees Celsius (4°C) you will need to consider frost protection for your solar water heater. As the temperature of water approaches freezing, it begins to expand. This expansion is significant below 4°C. Expansion of water and ice inside the solar collector can damage your hot water system.
Ask your installer about frost protection for your new water heater.
There are several types of frost protection available for solar hot water systems.
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Frost Protection Valves
Also known as 'frost dump valves', these fittings use a heat sensitive metal element that releases a valve whenever the temperature falls below 4°C. This relieves the pressure caused by water expansion and encourages water circulation which warms up the solar collector.
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Pump Circulation Protection
If the tank for a solar hot water system is on the ground (known as a split system), an electric pump is used to make sure water continually circulates through the tank and collector. This means that warm water from the tank reaches the collector and prevents freezing.
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Heat Exchange Tanks
This type of system uses a heat exchanger to separate drinkable water from the water circulating through the collectors. An anti-freeze liquid, such as glycol, is circulated through the solar collectors and back to a heat exchanger. Heat is then transferred from the heat exchanger to the drinkable water in the tank.
Choosing, buying and installing a hot water heater is a big decision. If you require more information about low emission hot water system technology, please refer to your plumber, installer or system manufacturer.
Heat pumps
Heat pumps generally do not operate efficiently in areas that experience long periods of cold weather. However, some models of heat pump have a defrosting function to allow the system to continue operating at cold temperatures. In addition, heat pumps may need an electric boosting element inside the tank to ensure a reliable supply of hot water during periods of very cold weather. Check with your supplier whether these are features of the heat pump you are considering. Although the heat pump might function it could cost a lot to run.