On extremely cold days, homes with gas furnaces are at risk of a specific problem which is freezing. If moisture doesn’t properly drain out of the condensate line, it can freeze within the line when temperatures drop below 32 degrees. To prevent freezing, the condensate line should be sloped at least a quarter of an inch per foot of PVC pipe. It should also be supported between the furnace and exterior discharge point and be as short as possible between the furnace and sidewall termination location. Condensate pipes on high efficiency condensing furnaces commonly freeze due to improper installation of the drain line. When the pipe sags, moisture can collect in the low areas and freeze when exposed to low temperatures. If the line is pinched or is too long, moisture takes longer to drain and may freeze as it cools during its travel through the pipe. Improper placement of the furnace is another installation problem that contributes to frozen condensate lines, which is common when a new high efficiency heating unit replaces an old conventional model. The location of the original furnace may not be ideal for the new unit if it is in an area exposed to colder temperatures. Measures that prevent your furnace from freezing are not always taken when a new furnace is installed. When the line freezes, you must thaw the line and then take measures to prevent your furnace from freezing in the future. You should pour warm water over the condensate pipe, and fill a hot water bottle and hold it in place on the line. Wrap the line in a heat wrap or electric heating pad and apply heat slowly using a hair dryer or heat gun. Setting up a space heater a few feet away from the line to warm the area. After unfreezing the line, it’s time to prevent it from freezing again. Place a small mound of rock salt below the exterior opening of the condensate drain line. Insulate the condensate drain line and floor drain and wrap the interior condensate line with heat tape. Working with a HVAC company will ensure proper installation and correct existing freezing issues.