I have a heat pump in the attic. The PVC condensate line has frozen twice when the temperature was in the low single digits. The HVAC contractor says that it doesn't freeze in the attic, but instead at the tail of the drain pipe that protrudes about 6" from the house. When that freezes, water backs up and the sensor in the furnace shuts it off to protect from flooding.
The HVAC contractor wants to reroute the drain line to a close-by vent stack, so that the drain line doesn't go outside into the colder air. This means that the water will flow into the septic system, an idea that gives me concern, especially in the summer months when the A/C is removing so much humidity from the air.
Is there another way to solve this?