Improvements made to the kiln in May 2009.

In my anxiousness to build a structurally stable kiln rising from a level base I made a crucial oversight in the original layout of the flues. The height of the chamber floor above the base level of the kiln produces flues that are much larger than needed; there is too much air space under the floor, the flames are drawn to the base level of the kiln instead of flowing directly under the chamber floor. This means the kiln chamber does not benefit from heat transfer from the flues into the chamber, and the excessive amount of air space under the floor is relatively cool. The end result is that the under-floor flues as originally built actually hinder efficient heating of the kiln chamber - the exact opposite of the intended effect.

I have now raised the base level of the kiln to create smaller flues which run directly beneath the chamber floor. This should lead to heat from the flues returning to the chamber and resulting in a more efficient kiln which reaches top temperature with less of a struggle (as was the case with my earlier under-floor flue anagamas). The area of the cross section of the flues is also now much closer to that of the two chimneys, which should help improve the draw of air through the kiln.

The kiln before improvements showing wear and tear of around 8 firings	The back of the kiln before removal of the floor
The floor supports, showing original excessive height	Base level built up to new height at back and left of flues
Kneeling in the flues, building up the base level	Building up the level in the centre of the flues. The bricks are spaced out to reduce the mass of the structure under the flues which could otherwise draw heat down by conduction
The completed new base level, finished with insulation bricks	The flirst section of chamber floor is refitted, showing the new shallower flues beneath
The gaps between the sections of floor are sealed to prevent sand draining into the flues. The wall of holes sits immediately behind where the rear stack of pots will be. The bricks radiate heat back at the stack to aid higher temperatures in this part of the kiln. The wall should also encourage a more even spread of flame, rather than the flames being drawn straight down to the flue entrance as before	The finished rear step of the chamber, with new silica sand.
	Left: completed cleaning and repair of the kiln insides