Verifying alignment of Casa 90 vent

[Alan]

My Casa 90 is up on the stand at last. I want to double-check the alignment of the vent:

The vent has a flat, rough side (the open side of the mold I suspect) and a smooth, cast side. The smooth side has a ridge running along one of the long edges.

If I understand correctly, the smooth side goes down, the frontmost edge of the vent aligns with the frontmost edges of the dome, and the ridge goes toward the front in order to partially make up for the slope of the dome. With this alignment, a significant portion of the vent opening is blocked by the edge of the dome, not unlike the slot of a fireplace chimney.

Do I have it right? (Photos of the parts aligned dry attached)

Thanks!

[james]

That's right

Hi Alan,

That's right. You need to use some mortar to get the vent to level. The vent piece can be used either flush with the front of the oven, as you have it, or hanging over. A majority of installations put the vent flush, so that you can use any type of material to trim the front of the oven.

James

[Alan]

Thanks, James. I think that my plans for the arch in front will work either way. No preference with respect to good draw?

[james]

Good draw

Alan,

That's right. They both draw well. It's sort of an "up and back" path that works well, get's the hot air out of the way, and lets you do the entry design that you want.

James

[Alan]

Not unlike a Rumford fireplace design. See http://www.brickinfo.org/BIA/technotes/t19c.htm (drawings about 1/4 of the way down and dimesions just below). They specify a 4" slot for a 12x16" flue.

In case you've never heard of Count Rumford, his treatise on fireplace design was published in 1790. The design works so well that building codes have been modified to accomodate it. The up-and-back offset prevents downdrafts from pushing smoke backward. The narrow slot creates rapid air flow.

[james]

That's right

Alan,
Excellent. The Casa vent pieces are all refractory, not metal or concrete, so they get hot, draw well and will last. The vent path works as you described. The Count would be happy.
James