Burner combustion fan speed for best burn/efficiency?

ken wrote:let me see if i'm getting this info right. on the Keystoker there is a plate that covers about 30 % of the combustion fan were the air is pumped in. so i should open the area all the way , as in remove the plate to get 100 % air into the grates. then adjust the stoker to maintain my 2" of ash?

Ken, I wouldn't open that cover without measuring the stove draft, I use the draft gauge or manometer to adjust the opening until I get -.03' to -.04" WC by measuring directly in the stove during max fire. Then I take a peak at the flames, if they are nice and blue I leave it alone.

While I'm not familiar coal stoves at all, I just want to point out to adjust the combustion fan for optimum combustion efficiency requires instruments to measure the flue temperature and the percentage of CO and O2 gases in the flue. The objective is to have just the right amount of air, plus a little safety factor, for combustion. Too little and you create CO, too much and the heat is carried out the flue by the nitrogen in the air. On a solid fuel burner the measurement and adjustment would be made at full output. At all other lesser operating conditions the setting would not be optimum, unless the combustion air would be somehow reduced. In an oil fired or gas fired appliance it's straight forward to set the right amount of combustion air because the amount of fuel burned is a constant, set by the nozzle size. It just cycles on and off. Not so in a solid fuel burner.

Yanche,

You are correct about the most efficient combustion, but in our little home heating stoves that works only with a constant, non-changing firing rate. But most of our little stoves have the coal feed changed often and the combustion air fan doesn't exactly adjust the air flow in sync with the change in coal feed. A couple years ago I'd set my old Alaska stoker's combustion air, coal feed & draft with a Bacharach kit to get the best combustion. Once I got the fuel and air mixture the best I found that as long as I didn't change the feed rate it would burn optimally fairly well. The problem came when I wanted to get more or less heat from the stove. The combustion fan did not exactly increase or decrease air flow in proper porportion to the increase or decrease in coal feed, even when I solely used the Alaska tri burner style reostat to control both the feed and the combustion air in unison. I'd have to readjust the feed/air again to get it optimum. I did learn to have some reference points after a while but it was just not convenient to reset everything each time I wanted more or less heat.
In larger or industrial coal fired units with more sophisticated controls of course this would not happen as extreme. However our little home stoves just are not built this technical. Not that they couldn'd be of course. It's fairly simple technology and is used all the time even with small, but variable btu input, home heating equipment.

i'm still having trouble getting a complete burn or getting enough heat out of the stove.......matthaus helped me out with a combustion fan.....i runn that all the fime and i have been messing with the carpet settings........best burn i've gotten in a while is having the rheostat turned down and the carpet feed at just about max stroke.....only problem is yesterday one of my pussycats must have been cold and turned up the rheostat and almost melted the stove........should i have the stroke near max and the carpet deed on slow?......less stroke and more feed speed was getting me a heavier ash pan, although i still cannot burn the coal to powder like the hand fed stove.........somebody make an appt so i can get a coal trol hehe

You'll never get ash from a stoker stove like you get from a hand fed. Here's the ash from my Blaschak burning Keystoker:

You'll always see some 'unburnt' pieces, shale, etc. in the ash. I run the combustion fan 100% of the time, keep the stroke adjusted to get me a nice idle fire with 1:15 every 10 minutes on the idle timer box, and about 2-3" of ash at the end at full fire. The room thermostat does the rest.

I'm still learning about this stoker thing, right now I have the Alaska set at full speed, it's got the combined stoker and combustion fan motor, a separate combustion fan that runs full speed sounds like a good idea. I think adjusting the feed rate and the combustion fan speed at the same time introduces to many variables into the mix.
Anyway, the motor's running full speed, I adjusted the carpet travel until I achieved about a 1 to 1 1/2 long burn area. Heat production is a little low, but it's not that cold out this afternoon.
I have the blower on the stove on a thermostat.
Rather then have to increase the feed carpet travel to increase or decrease the burn I would rather adjust the feed speed, leaving the combustion fan at full speed. Is this possible? Is the feed travel set to the max with this method?
Also, I think I read about a reference to a HI/LO burn control for the feed rate. This would be a good idea to have when I got the hot water loop connected. When there is a call for water heating from the aquastat I would need a higher fire, when the water temp requirement is satisfied, a drop to a low or idle fire would be a good idea, esp. in the warmer weather when heating is not needed.

Not completely clueless, but just thinking...