If you think your heated rock isn’t working properly, put it in your freezer for two hours. When you remove it from the freezer, plug it in immediately and it should start to feel warm.
This decorative bird bath de-icer is constructed of cast aluminum with a molded finish designed to resemble a rock. It is thermostatically controlled to operate only when necessary and is safe to use in all birdbaths. Using only 75 watts of power, the Heated Rock maintains open water, even in freezing temperatures. The surface is paintable so you can match the colour of your bird bath if you wish. 3-year manufacturer's warranty.