The Jetstream was ahead of its time and first showed up for residential use in 1981 . We got ours in 1983 unit # 528 . It construction differs from its modern cousins in that its heat exchanger sits on top of a large refractory base ( fire chamber) . After 28 years of use the refractory needed a face lift .This repair was done Sept 2011 . Many cracks in the refractory liner , tunnel the rectangular piece under the pipe needed to be replaced , and the pipe the air injection tube the end into the burn chamber had burnt off .The flaked gray colored material around the top of the base is aged stove cement . Cracks filled with new refractory cement done in stages , damp cloths over the newest sections to slow the curing process . The new air injection tube and tunnel in place . On the newer down drafting boilers the tunnel is called the Nozzle . This was the third tunnel installed for 28 years of operation and is considered to be a regular maintenance wear item . The tunnel can easily be replaced through the clean out door at the rear of the base . Moving the heat exchanger back to the base . A overhead track makes thing a lot easier on the back. There is a 1" layer of stove cement between the base and the heat exchanger to form a gasket between the two sections . The clean out door is just below the air injection pipe . This a new refractory liner . This is a complete new base and liner . The area between the liner and the metal box is filled with vermiculite. You can also see where the air injection tube enters the burn chamber , the slot across the end is recessed on the right hand side to give the injection air a swirling effect in the burn chamber .
I could have gone into much more detail on the above repair but will leave it open for questions . I attempted the same repair in 2006 but with very poor results ,learned a lot from that first attempt . Because of the large amount of refractory in the base it needs at least a month from the last fire until you can start the repair . To the hand the refractory may feel cool but any sooner and the green refractory will not adhere to the old . Incorrect mixing technique of the new refractory. And the biggest mistake was the gradual curing times required with the first series of small fires . This repair to date has been a complete success .
Very nice my friend. When did you do the repair? And how long did it take? I have replaced my nozzle in my Wood Gun once. Have been operating for 2 years now. It was a simple job and I hope I don't have to replace the large refractory in mine for a long time. How is the temperatures up your way now?
Looks like you should get another few decades out of it! The nozzle on my boiler was showing some wear after about 15 cords of wood through it. Due to the design I was able to come up with a cheap way to extend its life -- a few fire bricks cut to fit make a cheap 'nozzle protector'
The fire bricks work great and show almost no wear after about 7 cord. But to be safe I bought a couple spare nozzles if I ever need them, cheap insurance. Here is the current state of the firebricks -- they shifted a little but not enough to effect the secondary flame.
Yes. I love the avatar Mike. That's it, I'm switching to Gandolf. Nice job on the nozzle with the bricks. Good idea smeagle.
The repair was done Sept 2011 and in total took 5 weeks; 4 of those weeks waiting for the refractory to cool. For the new refractory to adhere to the old, the old has to be sprayed lightly with water and the old surface has to stay damp and 4 weeks was the magic number for this to happen. Curing for this repair took 56 hours. The Jetstream manual said to burn 3 lbs of wood every 2 hours just using the draft inducer by leaving the loading slightly ajar and to repeat this procedure at least 5 times. This time around I decided to do ten 3 lb loads. One of the things that I noticed at the end of the fifth burn was that the burn chamber walls were still quite black with soot and I attributed this to the burns not being hot enough to achieve complete combustion. Wrong conclusion. At the end of the eighth two hour burn cycle, the bottom inch of the burn chamber turned gray and every succeeding burn cycle yielded another half inch or so of gray appeared up the refractory burn chamber walls. The reason the walls were still black after the fifth burn was that the water had not yet been driven from the refractory. It took 24 burn cycles to turn the entire burn chamber gray. At the end of the 24 cycles, I then burned three small loads of wood just using the draft inducer with the loading door ajar. When the loading door is closed, preheated combustion air is then injected into the burn chamber and the high temperature burn then takes place. I'm expecting another 10 years or more life from this repair as there are no visible cracks as of yet! The weather this fall has given us one light frost on the last day of Sept. These are two nozzles that are both homemade. It is about a ten minute job to change a nozzle; just unbolt the 4 bolts of the clean out door, slide one nozzle out and slide the other in and bolt up the door. Done.
Interesting. I am looking into building my own gassification boiler. I like that Jetstream design. I am in some what of a unique position. I work at a taconite mine in Minnesota. Each spring we take our pellet firing furnace off line for a 4 week maintenace outage. Part of that is refractory work. The guys who do the refractory contract usually end up throwing out about a 55 gallon barrel worth of gunable refractory when they clean out their equipment at the end of the job. I asked them this spring and they are more than willing to shoot a casting for me if I bring in a form. This is some serious high temperature stuff. Runs at 2800 degrees, 24/7, for 11 months straight in a highly errosive atmosphere. I figure it should survive a wood fire okay.
This is the refractory liner. The liner is surrounded by garden variety vermiculite which gives a form of high temperature insulation between the liner and the sheet metal box that surrounds the complete base. I know of a case where a non-thinking owner stacked firewood against the boiler while it was firing. The floor got hot enough to ignite the wood. If the refractory that's available can operate continuously at 2,800 F that should be good.
