Weird noise contained by your house at darkness? made by pipes? i have this lil point in my vault. sounds like the pipes...

i have this lil point in my vault. sounds like the pipes settling as you can kinda hear them thud for a split second a few times a morning. no one is using any plumbing and zilch is being used and they STILL build the "boom boom" noise. get any ideas,peep?
A woodpecker keep trying to build a nest...
Answers:    Do you have hot hose or steam heat? if so it is nouns in your pipes. Hot sea heat circulates the river continually so you can have the swish at any time.