Water in older down-draft heat/air vents

[mpsurge]

I am planning a change in my system to a typical up-draft [vents in ceiling, right?] and I was wondering what to do about my vents in the floor.

You see, the reason for the change is that when there is WAY too much rain like last season, the vents fill with water. Not a good thing.

Any viable suggestins on how to close them up and prevent the water from coming in?

[proplumb]

i do this a few times a year due to the same issues. i fill them up with gypcrete so there is no void and where the low spot is i put in a sump pump