Ash dump questions

[wirsbozo]

I'm getting a significant ingress of cold air from the ash dump for my fireplace. I've been puzzled by the dump since I moved in a year and a half ago. It has a brick sized opening, drops down a bit more than a foot, then leads straight back to a metal vent grate on the outside of the chimney, not a cleanout door. There's no easy way to clean the ashes out and not enough space to store ashes for years. Is this set up properly? Is it a vent rather than a dump? Am I OK to stuff ceramic wool down the hole to help seal it up for now? Would it be OK to use the fireplace with the wool in place? The fireplace sees occasional, not regular, use. Thank you! Pictures below.

 

[begreen]

That looks more like a fresh air intake and not an ash dump.

 

[wirsbozo]

That looks more like a fresh air intake and not an ash dump.

I think you're right. What, then, do you think would be the best way to stop all that fresh air from coming in through the opening when the fireplace is not in use? I don't see being able to get a tight seal with any sort of metal cover so I'm thinking ceramic wool placed in the opening but open to other thoughts.

 

[begreen]

Ceramic wool is ok, but it will not fully block air that is wind driven. Doesn't the little door seal it when closed?

 

[wirsbozo]

Ceramic wool is ok, but it will not fully block air that is wind driven. Doesn't the little door seal it when closed?

Unfortunately, it does not. There are decent gaps between the door and its frame as well as where some of the mortar has worn away on the fireplace itself. I suppose another approach might be to put some sort of cover over the vent on the outside, but haven't figured out an attractive looking solution to that yet.

 

[BillBurns]

I have seen magnetic sheet things that cover unused vents. It would block it good probably.