We bought our home in Dec. 2014, ten year old house. It started making a rumbling noises, as though it was thundering outside, and it seems to happen in the evening. However, sometimes during the day. We had the entire heating and air system checked out. We also just had a new 80 gallon water heater installed in February 2015. We just can't seem to figure out what is causing this noise?
I recently experienced the same issue. We just found out what it was and had it fixed. Apparently, there is a pipe that sticks out of the house from the HVAC system underneath the house that releases water that is formed during the cooling and evaporation process. We found out we needed to have the trap (device that collects debris) checked and cleaned annually. Because the trap was full of debris, water couldn’t leak out of the HVAC system and out the pipe causing the build up of pressure in the HVAC system (cause of the rumbling noise underneath the house). Eventually what happened was, our central air unit had pressure problem and could barely pumped out any AC. Once we had the trap cleaned, ever thing started to work again and the noise went away.
Sometimes it is air buildup in the water pipes, especially if your home uses hot water (radiant) heating system.
The air vents that are supposed to allow air in the heating system to escape are not working correctly, so there are pockets of air trapped throughout the piping system. Over time these air pockets accumulate and some sections of the pipes become water-less. When a gush of water is pushed into these "air" area, especially in vertical pipes, the water just falls right to the bottom like a hammer and creating these banging/rumbling noises. Once you solve the air-in-system problem, everything will be quiet.