We have had a goodman direct vent furnace and a Rinnai tankless waterheater installed and sometimes we have the smell of gas in the basement. It seems to happen when there is a breeze outside. Is this normal.

No,, its never normal at anytime to smell gas in your basement,, get it checked out asap if not sooner

No. Are we talking Natural Gas or Propane. If this is an exhaust problem you could also be venting CO as well.

All the more reason to get this checked out yesterday.