Short 'wall' inside bell to prevent direct flow out flue

Hi All

I'm close to building an 8 inch J with traditional barrel radiator and brick bell.

Pictures should be self explanatory. Question pertains to the final picture:









(Note: previous picture shows smaller floor size for the bell than the slightly bigger one I've since changed to.)



In the final image, I have positioned a short 'wall' inside the bell (indicated with the red bricks) to stop potential movement of the heat directly from bell-entry to flue exit.

Is the little internal bell wall necessary for the purpose I am speculating about?

If yes, what would be an optimal position and height for it?  

Thanks,
Dave

Hi Dave;
I have been told by Peter,  that no you do not need/want a diverter wall.
In fact, if you build one it must be counted against the total ISA (internal surface area) of the bell.
The heat entering the bell from the transition area will rise, following a path of least resistance.
Your exhaust stack appears to be  6" or so from the bottom of the bell.
Only after rising to the top will the air sink down and find that exhaust stack.

Hi David,  A nice simple design that looks like its going to do just fine for you.

Looking at the manifold opening in your second photo where the exhaust gasses flow into the main bell, the opening may be a little small. The larger the better as this is a bottleneck point that some people can have problems with proper draft.

EDIT - Second the motion on eliminating the little wall. The gasses move quite slow in a bell as they stratify out and any short-cutting would be so minimal that it would not be worth it.  Are you going to include any cleanouts?

Thanks Gerry

The manifold area will be approx. 480cm2 (1 brick-length wide X 3 bricks high).

The system size is approx. 314cm2. I have used the same 1.5+ ratio for the manifold before with no problem.

Re. cleanouts. Yes. First one via the removal of the barrel every few years, which will break a clay+sand gasket seal but that is easily redone. This will allow access into the manifold area.

Second at the bottom of the short wall of the bell on the flue side. As I've done before, the brick will be positioned there during the build, but not mortared into place. Brick gets removed, and a little 'door' fitted. The little 'door' will be basic wood+CFB, with the CFB protruding into the open slot. No hinge or anything, just a little cupboard handle on the wood that you can grab and pull the entire thing aside.

This also allows me to open that 'door' to shove burning newspaper into the bell directly under the flue to get the air-flow going. Worked a treat for a previous build.  

Hopefully final floor-plan, with cleanout 'door' area gap near flue...