• Understanding The Frost Valve

    A very crucial part of any solar hot water service installation when in a frost prone area, this valve will save you hundreds if not thousands of dollars.

    In Adelaide majority of homes do not have a frost valve installed that are built on the flat planes, but in suburbs such as Crafers, Lobethal, Woodside, Cromer and Aldgate in the Adelaide Hills you must certainly have one of these devices installed as these locations will certainly experience temperatures below zero for a handful of the months in the year.

    Hydronic Solutions

    Caleffi a manufacturer of hydronic solutions has offices located globally and supply their anti frost valve to plumbers such as us in Australia to assist in protecting our clients solar hot water panels from freezing and damaging them.  There is a very crucial trick which must be applied to the panels and valve in order to avoid the valve failing and not being covered under the manufacturer’s warranty.

    repairing solar hot water panels

    You will see many solar hot water panels in Balhannah, Stirling, Bridgewater and Mount George where the anti-frost valve is connected direct onto the panels.  What this exposes the wax bulb inside the brass housing to direct heat from the solar panels, a big no no!  What needs to happen during the installation process is the creation of a dead leg of approximately 250mm – 300mm in length. 

    This is created by using a straight piece of 15mm or 20mm copper tube with some solar resistant connectors.  By doing this it removes the Caleffi valve from direct exposure to the extreme heat from the water inside the panels in hotter months of the year.


    Caleffi offer a two-year manufacturer’s warranty on the valve, but if it is installed how I have described there will be no need to have the valve replaced under warranty in most circumstances.  During the extreme heat periods in Adelaide we often get a phone call to properties where they are reporting water running off the roof from there solar panels.  It can be because the anti-frost device has failed due to a poor installation.  During winter the valve can discharge water, but this is a good thing.  Through discharging water in winter, it enables water to flow through the panels and stop the formation of ice.  It is a well-known fact amongst plumbers around the world that still water is easier to freeze rather then flowing water, hence the action of an anti-frost device.

    Regular Maintenance

    Like most hot water services regular maintenance is required and these anti-frost valves are no exception to the maintenance that should be performed at regular intervals during the life of a system.  It is a recommendation that the frost valve be changed over at approximately 5 to 7 years of age which is roughly the half year mark of the panel’s life span.