Newb in need

Hey guys so basically I’m looking at this flu and wondering if it’s something I should write up as a defect. I know the smaller appliance should enter on top and it seems like technically the way this is set up he larger furnace is on top of the smaller water heater. Just an FYI the furnace is on he right and water heater is on the left. Also I see all this moisture staining and I’m assuming it’s safe to say it’s likely from the flu exhaust but what’s the deal with the metal plate on the wall ? Is it for flu clearance ?

Thanks guys

The metal plate is there to protect the drywall from the connector because the single wall pipe is too close, less than 6 inches, which is OK according to the Canadian code book I have if the spacing is 1 inch or more. The moisture looks like it might be coming down the outside of the chimney, check the flashing, boot and rain cap on the roof. It might also be coming from inside, indicating that the chimney might be too large and vent gases are condensing inside the chimney.