We are renovating a mobile home and we have noticed a pooping noise which happens every 6 to 10 seconds. During the winter months this is loud enough to keep us awake at night as the vent goes through the wall beside our bedroom. We are just finishing the kitchen and the sink is not connected at this time. Would the attachment of the sink create a " closed system" which would stop this noise or is it something else?
Thanks!!

I would love to be there to test my theory but I think your vent is venting warm air to the outside. The warm air allows expansion of the vent pipe, usually PVC. Try plugging the vent temporarily to stop the air flow.

One idea from a local expert is that a vacuum is created in the mobile home. When we moved here there wasn't a cold air return attached to the furnace. When the furnace is not working though, the popping sound still happens. This could be attributed to this same theory. Any thoughts?
Thanks DJ

Knocking, popping, creaking and crackling pipes are a common complaint, especially in colder weather. I can tell you what's happening and take the mystery out of it but you're not going to like the repair. When a draw is made on a hot water line the line expands against a pipe strap next to a stud and when you drain hot water from your tub or shower it goes into a chase that is a little cooler then room temperature. The heat expands the pipe causing it to rub against the stud to which it is pipe strapped. This is the sound you hear. As it cools it contracts and the noise is heard again. To repair it you must tear open the walls and locate the pipe strap that's causing the problem and shim it tight. Most people when they learn what causes it just elect to live with it. Regards, Tom