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I had problems with uneven feeding of pellet last winter. The problems almost completely went away by putting a 12mm copper pipe inside the feeding auger. Before trying this "fix" I thoroughly checked what the problem was all about by mounting a camera to watch the auger and streaming the picture to work so I could keep an eye on it all the time. And I probably would not have noticed there was uneven feeding without the oxygen sensor, it only showed up on the oxygen reading, no other noticable problems.
What happend was roughly this:
The feeding was nice and even for maybe 5-10 minutes. The spiral auger was mostly "floating" on top of the pellet in the auger-pipe, meaning about 1/3 of it was visible on the "up" side of the plastic auger pipe.
Then, the auger begun to slowly work it's way "downwards", and quite rapidly it disappeared from view, and went all the way to the "bottom" of the pipe, and after about a minute of so, it climed to the "top" of the pipe again and became visible. In the process of doing this "roundtrip" to the bottom, it transported much more pellet, which immediately showed up on the oxygen reading.
After this, since it just had transported much more than ususal, there was much less pellet int the auger, meaning that now it feeds much less than usual for a while.
Then it stabilized and returned to normal normal operation for a while, and the cycle begun all over again.
I then concluded that the root of the problem was that the spiral auger was too soft, ie. it could bend too easily, so I tried inserting a stiff copper pipe in it to prevent it from bending, and as I said the problem went away. The spiral never dips to the "bottom" of the pipe, and the fluctuations in the oxygen reading are much smaller.
Before trying this I tried varying the angle of the auger, all from below 30 degrees to over 50, my conclusion was that over 50 makes the problem much worse, below 45 does not help.
Senest rettet af
motoz 15 feb 2013 15:02, rettet i alt 1 gang.
