In fireplace business terminology, B would be the opening. However, if your question is about clearance from combustibles, that has nothing to do with the opening with a fireplace like yours. The clearance has to do with the testing that was done by the manufacturer and published in the owners manual for the fireplace.

The clearance to combustibles for a heat circulating fireplace are generally taken from the top of the upper louver, which is A in your diagram. That clearance depends on what is stated in the owner's manual.

Bottom line here is, you need to find the owner's manual. There should be a metal label inside the fireplace somewhere that has the make and model number. Post a picture of the label that is legible and I may be able to help you find the manual.

Also, you cannot cover up the areas that had vents. What are your plans for that? There are fireplace doors designed to cover the entire black metal part of the fireplace including the vents. You can find examples here!

Hi, Thanks for the comments and help. I have found the label but could not get a good picture for you. The vents/grill opening top and bottom will have the original grills put back in place. The original glass doors will also be re-installed as will the top metal trim piece (which is the same as the 2 vertical side trims (about 5" in wide)).

So it looks like from the opening (B - Yellow line), for the sidewall (left and right) I need to extend another 9" from the existing black metal trim?

This seems odd because the original marble slab was only 7" wide. This makes a total of 12" of non-combustible from the opening.

I could not locate the manual online but I believe the label provides the info that is required. This is the info on the label.

Warnock Hersey

GSW Heating Products Company, Hamilton, Ontario

Manufactured by Kingsman Industries Winnipeg, Manitoba

Model: GSW 7200

Report No: 5502 (07/88), 9144 (09/91)

WH 29228

Minimum clearance to combustible construction
Bottom 0mm/0in
Top 0mm/0in
Sides & Back 0mm/0in


To spacers front no combustibles permitted on fireplace face.
Mantle: 470mm/18.5in. measured from fireplace opening.
Sidewall: 355mm/14in. Measured from fireplace opening.
Hearth extension: non-combustible material extending 405mm/16in.to front and 205mm/8in. to sides of fireplace opening.

Where are you getting all of those clearance numbers? Are they on the label? If that is the case, the mantel clearance of 18.5" from the fireplace opening would be from the B measurement. With that said, there is probably a maximum depth of a combustible mantel at that height, which is why the manual is important.

Sidewall would usually mean of you have the fireplace installed close to a corner, the opening (B) cannot be closer than 14" to a perpendicular side wall. Your fireplace is installed diagonally across the corner, so the side will is well within that range.

What are your plans for refacing this fireplace?

Hi, All numbers came from the label. I was unable to locate the manual at this point.

In terms of refacing, if we had correct clearance as it stands now, we would prefer to repair the drywall and just paint. But if we have to cover up the drywall, then we were thinking of herrinbone tile. We would tile from the metal trim up to mantel and to the left and right edge. The mantel is 18" from the top metal trim.

The hearth in front we would most likely do a herringbone tile.

Always open to consider suggestions.

Thanks

So, if the drywall does not project out beyond the black metal face of the fireplace, you can just leave the drywall. However, drywall right up to the black metal will look quite unfinished in my opinion.

Ok. Thanks. The drywall currently extends underneath the black metal trim. It does not project out past the face.