Industry Articles & News

Failed Furnaces and Frozen Pipes

The story you are about to read is true. Only the names have been removed to protect the innocent.

Frozen pipes in a home caused extensive water damage. The furnace in this home was an induced draft furnace – meaning that it used a fan to draw combustion products into the flue which then vented through a PVC combustion supply air duct and a PVC exhaust vent duct to the outdoors.

Determine the cause of the frozen pipes


The furnace
The thermostat
The furnace installation

Our investigation revealed that the furnace in question was operational both before and after the pipes froze, and there were no indications of local power outages. Inspection of the furnace showed that the outside vent was approximately three inches above the ground. Examination of the manufacturer’s installation instructions showed that this outside vent must be installed 12 inches above the ground or 12 inches above the highest anticipated snow level, whichever is greater, to work properly.

The manufacturer’s troubleshooting guide further explained that when the outside vent is blocked by snow or other objects, the furnace will generate a fault code and not ignite until the blockage is removed. Weather information at the time the pipes were frozen revealed that the accumulated snow did exceed three inches in height where the outside vent was located.

FINDINGS: Our conclusion was that there was not a failure in the furnace or thermostat in this home, but that the outside vent for this furnace were improperly installed. The incorrect installation resulted in a fault code that caused the furnace to shut down which then resulted in the pipes freezing in this home.