We are in a 3 level garden type condo development.
We are on the second level, with a unit above us and a unit below us.
When the unit above us turns on their hot water going to thier shower, we hear a ticking, tapping and knocking sound from the cpvc pipes, for the first 10- 30 seconds and then it goes away.
This noise also happens on the copper pipes leading to the aquatherm hot water heating system. Both the cpvc and copper pipes are immediately above our bedroom and are immediately coming from the hot water tank.
QUESTION: could the hot water tank be creating air or gas and could we be hearing air or gas moving thru the pipes????? I have been able to cut away part of the ceiling and touch the cpvc pipes while the noise is happending and a can feel the pipe vibrating- as if there was air and water turbulance flowing thru the pipes.
The noise in the pipes usually happens after period of time, where the shower is not turned on and the hot water heater is not on. Generally happens early in the morning say: 4;00am or late at night.