Len's Rocket

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The last time I was not happy with how my heater burned. It smoldered too much and there was too much smoke coming out of the exhaust. There was some smoke back even though the flow was generally in the right direction.

My thought was that the fuel was to blame. That there was not enough of it, and that it was blocking the air flow.

As I thought about it more... I decided there was more to it. I remembered some of my experiences with camp fires. They worked best when there was at least part of the fire surrounded by hot coals and wood. A hot spot. There was only 10 inches of uninsulated fire tunnel, but that was where the primary combustion was happening. Insulating that part of the tunnel would probably help keep the fire hotter. I also learned, that only 1/4 cross sectional area is needed for air intake and thought that blocking some of the intake off would also keep things hotter with less new cold air coming in. So I insulated the rest of the tunnel and I put bricks in such a way as to block off all but 1/4 of the intake.

I also thought that using the same kind of fuel package would give me a better idea if my changes had improved things rather than new fuel, so I used a similar fuel package. I realize this is marginal fuel, but feel this is a better test than wonderful fuel.

I used more Roxul wrapped around the tunnel. I have a lot of sheet metal from changing a camping trailer to a boat trailer and used that to cover it. I thought that having air enter the bottom was best, so the top half of the air intake is blocked.

insulation and bricks.

Right away there was less smoke... and more roar. Last time I had to add bits and pieces in the air intake to get things going, but not this time.

Less smoke.

The flames looked better too.

Nice flames.

At one point the fuel fell down and blocked much of the air. I thought adding air beyond the fuel might help, so I put a 1.5 inch pipe through to the other side.

secondary air pipe.

Tim is showing us how the smoke virtually disappeared. Now there was just heat waves. The barrel top got hotter... all around goodness. Even when it was down to embers the heater kept on drawing properly and the little wisps of smoke went towards the riser.

No smoke.

Even though the feed worked as it should, there seems to be more work required on it. Because of the way the cartridge cap fit on, I had to put the connections backwards or up side down and the condensate leaked out the joint. So I think I will turn the pipe right way up and figure out a better, leak proof cap. This will also leave one less place for the fuel to catch on. The leak proofing is essential to keep smoke out of the house.

yucky gunk.


I will use the cap of the fuel cartridge to cover the air intake letting in only 1/4 of the cross sectional area. I will try to make it look nice too ;-)

Instead of a pipe for secondary air, I think I will use sheet metal shaped like an "M" (like the M on Mario's hat if you play games) but stretched out so the middle acts as reinforcement for the bottom while the two bumps take the air beyond the primary burn chamber. This will be easier to replace when it burns through than the burn tunnel would.

I think it is time to try bigger fuel and mass.

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