This is the heart of the Jetstream, the refractory liner. The round section is the burn chamber and the rectangular is where the ash particles settle out before passing up through the heat exchanger. The nozzle sits in the center of the ash settling area, the ash clean out opening at the bottom.
Most common area for the liner to fail is between the two chambers.
For example, if the wall between the two chambers has failed and you have to make a new nozzle, a new stainless steel combustion air injection pipe, plus the stove cement to make the gasket between the base and heat exchanger, you can expect to put out some where around $ 800!
This is the complete new base, liner with insulating vermiculite between the liner and the sheet metal box. 1,400 lbs approx.
When the heat exchanger is mounted on top the base, 1 inch of stove cement is spread over the base surface to form a gasket. You cannot skimp on this gasket as it serves two functions; firstly a gasket and secondly it provides for good heat transfer between the base and heat exchanger.
The sheet metal box with clean out opening and round hole for the combustion air tube.
Looking in the clean out opening with the nozzle in place. The nozzle is a maintenance wear item that has to be replaced every 5 to 10 years and can be easily inserted in through the clean out door without dissembling the boiler.
Two home made nozzles, fairly easy to make. Kerr Controls in Truro, Novia Scotia I believe still stocks them.
These are stainless steel refractory needles used when mixing refractory. High temperature mini re-bar
For me these boilers are fun to play with. Also I believe the manual's instructions for curing refractory are inadequate. I've learned the hard way!