The following images illustrate the chimney connection into the side channel of a contraflow heater.
The brick used in the channel are Chinese SK34. The core is in Mount Savages High Heat. Layed in Mount Savages Super High Mull.
An 8 x 12 inch tile is gasketed with ceramic wool. This acts as both smoke and expansion gasket.
While casting the oven modules the previous day, a 9 by 12 inch square, 2 and a half inch thick slab was cast. The castable used was Vesuvius Tough Gun.
With this slab the opening for the tile could be spanned, cutting the slab to shape as necessary. The ceramic wool gasket is sponge parged with refractory mortar. The 5th course of bricks in the channel wall are cut down to the line of the top of the slab, which was cut and dropped down to the top of the flue tile. The slab had originally been cast to exactly two courses of brick high i.e. 9 inches.
The connection will lead to a chimney 3 feet away from the heater.
The advantage of using castable to span the connection opening is that it will not be susceptible to rusting or moving as much as an iron lintel - and be easier to install and stronger.
As the connection was against the rear manifold wall, i.e. to the extreme right of the channel wall, it would have been inappropriate to use a skew cut brick lintle as illustrated in the article Chimney Connection #4.
View down the side channel, the wall of which will be continued in SK34 just until two courses below the ovens under hearth exit openings. From there the superior High Heat will be used.
See also the finished project