I have a 4' section of 4" copper drain line that is a heat exchanger with coils of tubing around it to recover heat from drain water. It was available commercially when I installed it about 15 years ago. It's in a house and the rest of drains are PVC. It's in a vertical stack and coupled with fernco style rubber couplers on the ends. Just discovered I have a leak and found about a 1/16" x 1/8" hole clear through near the top of it and a vertical crack running through the hole. When I tap on it near the crack it sounds paper thin. Other areas and the rest of the top seems solid when I tap on it. The thin spot is not near any soldering - just out in an undisturbed area. The tubing was fairly thick when installed but I don't have the measurement and can't get to the ends easily until I take it out.
Any idea what is causing this and how to avoid it? We are on city water. It's hard and we have a softener. On a septic system. Don't use drain cleaners. We do use chlorine tablets in a toilet unit that drops a bit in the bowl each flush.
Second question is how to patch. I will be replacing it with a PVC section for now. Not sure how long the thin spot is until I get it out but it seems to be just on the top end. The coils on the outside will make an outside patch difficult so thinking something on the inside if it doesn't extend too far from the end.
Any idea what is causing this and how to avoid it? We are on city water. It's hard and we have a softener. On a septic system. Don't use drain cleaners. We do use chlorine tablets in a toilet unit that drops a bit in the bowl each flush.
Second question is how to patch. I will be replacing it with a PVC section for now. Not sure how long the thin spot is until I get it out but it seems to be just on the top end. The coils on the outside will make an outside patch difficult so thinking something on the inside if it doesn't extend too far from the end.
