Refractory Core Maine-Et Loire 2006

After detailed preparation. I arrived (late March) on site in Anjou not far from where the rivers meet. The object was to build a Finnish style contraflow refractory core. Located on the second floor of an industrial water mill that was undergoing complete renovation.

The core would contain 750 42% Al So refractory brick and 100 common brick along with fourteen 25kg bags of castable refractory concrete. There would be an auxiliary indirect bake oven incorporated in the upper chamber.

The core would be built to take Upo s 0018 fire box door, and 0213 oven door.
It would be faced in clay brick by the client.

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My place of accommodation, in a near by village, for the duration of the project.

The Mill built in the 1850 s
The buildings on the opposite side of the lock are, foreground, the granary, and background, the lock keepers house.

Mistletoe growing by the river.


Neighbors upriver.

View of ruined and more modern farmhouse on the river.
Note the bread oven adjacent to the ruined farm buildings.

The mill originally had two water wheels though since 1960 it had been powered by electricity. Three water channels run from end to end of the building through the basement.

Much of the old machinery survives intact.
Power Train Machinery (6 images)

Today the mill is divided into two separate dwellings. The project was undertaken in the dwelling occupying the left half of the building.

The foundation of the heater and chimney consists of five tubular steel pillars straddling the middle waterway. The pillars support a reinforced concrete slab.

The footings and foundation of the building are exceptionally well built as the structure had to withstand weight of the upper floors, the vibration, of machinery and the erosive action of the water running through the channels.

View alternate image of foundation

Foundation slab with the first five rows of the core layed up in clay brick and type N mortar.
The rectangular hole allows the ashes to drop through the foundation slab into a depositor.

The recess in the front forms a combustion air intake channel allowing combustion air to enter by the cast iron air intake door installed on the facing, and be deflected, by the refractory brick deflectors, on to the fire.

The first row of the rear manifold and the central chimney connection. The chimney connection would be custom built in refractory brick, not being tied in to the wall of the rear manifold.

Finished rear manifold and flue connection. The opening is bridged by 10x10mm, 460mm long angle bar.
The rear wall is at the same height as the first 4 rows of clay brick.

The subsequent rows of refractory brick, forming the hearth, are of crucial importance in strengthening this masonry and angle iron lintel. This is a potential point of weakness though cannot be avoided.

Work needs to be done with the utmost of care.

Custom built flue connection in refractory brick.

The first section of clay flue tile in position.
It would be removed during construction of the core.

Sloped fire box floor. This allows ashes to collect together over the grate, burn quicker and so allow the chimney damper to be closed as quickly as possible, aiding overall efficiency.

Base courses of the sloped firebox hearth seen from the loading opening.
The opening in the fir box floor is cut to take the Upo 0413 cast iron grate.

The fire box consists of four double with shiner courses. The inside course can be removed and replaced should the fire box walls become damaged in the future.

Recesses are ground or cut into the top two bricks at the front of the fire box walls. This allows the angle iron lintel to sit flush with the top of the bricks forming the rest of the fire box walls.

The fire box lintel is negotiated by the first 4 rows corbelling.

Detail. The exposed corners of the corbel cause turbulence which promotes mixing of the smoke, flame and secondary air. The whole bricks used in the corbelling (as opposed to skew back, bricks) enable the whole fire box ceiling to be layed with a simpler and stronger bond.
This heater does not use the Ventura effect to encourage secondary combustion. The wide vertical through running up the rear wall acts as a fire tube.

The small sections of angle bar welded to the angle bar lintel, will hold refractory brick splits that will act as a thermal shield, protecting the angle bar lintel itself.

As the heater's fire box is exceptionally deep, and the over air draught blows the fire towards the back of the fire box, the angle bar lintel receives little or no flame bight. The lintel would also be ok without the added heat shield.

Final row of corbelled brick before the oven under channel is layed.

From the mezzanine.

The ovens hearth slab in place, with 'bio' local alternative to ceramic paper.

The ovens hearth, side walls and top slab in place.

The oven from the front i.e. the loading opening. The opening beneath the hearth is to allow access for potential future cleaning of the under heart channel.
I have never found this to be necessary though at 1m. this was the deepest core I had built, and thought the addition of an inspection opening prudent.

The core before the side walls are built.

Completion of the side channels.

Detail of the fire box showing the ash chute and the cut out for the grate.

Looking upwards from the firebox.
The refractory concrete capping slabs can be seen in the background.

The fire tube running up the rear wall.
Corbelled ceiling and bottom of the castable slab that forms the rear wall of the oven.

Fire box loading opening a 46cm wide.
The angle iron lintel is fitted with two half refractory bricks that will act as a heat shield.

The two refractory brick that are dry layed at the front of the hearth are used to deflect primary air on to the wood load at a 90 degree angle.

The finished core with its two side walls and capping slabs.

Pyromasse, Montreal. April 2006

Articles by Marcus Flynn

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