Gutter help!

I recently removed and attached sun porch from my home, leaving the concrete pad as a patio. However, the gutter system on that side of the house drained onto the roof of the sun porch, down into gutters on the sunporch and away from the house. Now, I have to put in new gutters on the house above where the porch used to be an noticed that beneath where the gutters will drop, on the patio, is a drain for the gutters to empty into the ground. It was actually inside the old porch, meaning it was at one time used as gutter drainage. It has a piece of wood in it but I assume I can run my new gutters into it? Where would that go to, into the storm sewer? I noticed there are two others around the house but none are being used for gutter drainage and all have been cover with a piece of wood? I'd like to use it is possible, especially near the patio because routing the gutter near it will be tough.

thanks

 

Test them with a water hose first. Those tend to clog up with dirt and debris over time.
You may be able to snake them out or flush them out with a pressure washer. (They should drain into the storm sewer system.)
Good Luck!
Mike