I recently nailed a Central heating pipe. Guy came out to replace and intended on replacing the elbow joint and damaged pipe. He tried to heat the elbow but it wouldn't come off so instead cut in new copper pipe back into existing elbow joint. After it had been heated. No leaks in system. Is this safe? Or should the elbow joint be replaced? Anything I can do to strengthen the joint?
Unlikely to be an issue. If he heated it up and it didn’t come off then possible there was water in it and the solder didn’t melt. If it did melt but wouldn’t come off for some other reason then it would have most likely just remade the joint. He’d have been better off cutting the whole section out once he’d heated it but to be honest if it’s not leaking it’s fine.