This clunking sound is one loud sound followed by a few smaller clunks. It seems to be coming from the water supply pvc pipe that supplies water to the heat pump in the basement. The sound starts near the heat pump and runs back towards the bladder tank 25 feet away where the water supply enters the basement. A 1/2 hp submersible pump supplies the water from a depth of about 40 feet. I have secured the supply pipe to the floor joists, but the noises persists. This system is almost 20 years old. It has only been making loud noises the last couple weeks.
Could this be caused by air trapped in the pipe? If so, what is the remedy? Thanks