Helpful member
Maybe a very stupid question but there is some sort of ventilation shaft under a metal cover in both our bathrooms. At first, I thought it's drainage for water on the floor but then I noticed it's screwed in tight. So I went to unscrew it and investigate :) Inside is a hole and a bit of water around it. It smells a little bit.
What is the purpose of this? Since it's covered and sealed, it's not really doing anything. However, when opened, there seemed to be a draft. There is one in each bathroom and then one in the "technical room" (where boiler, washing machine etc. are). The one in the technical room smells. Is it OK to pour some cleaning chemicals in there? Or at least boiling water?