Two holes (not cracks) leaking smoke: mortar or furnace cement?

[Fio]

After building my second drying fire, I discovered that there are two areas near the vent that I did not seal, and are leaking smoke. I need to patch them. One is a hole 1" in diameter; the other is a narrow strip about 1" wide and 18" long, between the vent manifold and the brick arch in front of it. The brick arch is purely decorative, and is mortared to the front door bricks. But the top curved part is not mortared to the vent manifold, hence the gap. This was a building mistake on my part.

I plan to patch the hole with a hunk of firebrick. For the narrow strip, I can probably wedge in some firebrick strips leftover from building the dome. The question is, do I need to use fireclay mortar or furnace cement? I want to avoid using mortar because it will take longer to dry and cure before I can continue building drying fires.

Thanks,

- Fio

[CanuckJim]

Holes

Fio,

Not absoltely sure without being on the spot, but I think furnace cement should work just fine, so long as it's not a working part of the oven interior.

Jim