The best way to keep the propane in your tank from freezing is to keep the tank full. A full tank safeguards that there is enough vapor pressure being produced for your system to continue operating as it usually does. A full tank also diminishes the risk of a build up of condensation which may taint liquid propane.
In addition to keeping your tanks full, there are a couple other things you can do: First is to keep snow buildup off your tank. Snow building up on your tank can hinder its ability to correctly warm when the sun comes out, making the problem worse.
Second, although it seems counterintuitive, is to turn DOWN your thermostat. This is because, if your furnace is running at 100% you aren’t giving the tank enough time to re-pressurize itself. By giving the furnace and tank breaks during the day you help keep your propane system running at peak efficiency.
Some people use propane tank blankets to help keep their tanks from freezing, especially in more extreme climates. However, as suggested above, if you do go this route, be sure to uncover the tank when the sun comes out. While not critical, it can help you save a little on your power bill when you can unplug the propane tank blanket and let the sun do the job for you for free.
Finally, always make sure you are running properly certified tanks. While a tank that has recently expired may still be safe to use, it’s highly recommended that you trade it for one that is new or has recently been inspected and re-certified. This too will help ensure your propane system is running at its best.