My water heater vent runs to the basement wall. Right underneath (maybe 6 inches) is an opening (I’m not sure if that runs to where the vent goes out or not). Attaching a picture. Is there any reason the opening is there and shouldn’t be covered, or should I go get something to cover that with? Since hot air rises probably not an issue, but I guess if wind gets in it could blow in?
Thanks for any insight.