Hello everyone! I moved into a new-construction house about 6 months ago, and for the past 4 weeks I have been periodically hearing a strange gurgling sound in our wall. I only began to hear it after using a rarely-used bathroom. I initially thought it was a plumbing/water issue, so I had a plumber come check it out. He informed me that there are no water pipes where the sound is coming from - very strange. I've tried researching this issue online, but I haven't found much. I feel like it has to be related to me using the sink, toilet and shower that rarely gets used, but I can't figure it out! Part of me thinks it might somehow be a furnace/HVAC issue... If anybody has any suggestions or thoughts I would greatly appreciate them. Thanks!