Help with Dark Spot and Air Setting

Fired up the DF 520 on Sunday. Alot of hard work but I'm not sending my home heating money to the middle east. I'm helping out the local economy right here in PA! The EFM has exceeded my expectations up to now. I like how the unit kind of laughs at a heat demand with all that steel and water reserve holding the heat. The design is decades old and it's built like a tank!

New to stokers, I've never seen a properly adjusted unit in operation. I have my settings at 4 teeth and 4 air just like the manual says. I'm concerned that the manual talks about a small dark spot in the center with new coal being fed in with a 2 inch ring of ash on the outside ring. I see the ash ring. I would approximate it at 3 inches. I don't see a defined "dark spot" in the center. What I see is a darker area inside the ash ring that doesn't lead to a dark spot.

At first I assumed the darker area was the dark spot, indicating not enough air. I turned up air to about 4.25 and didn't see much change. I'm don't want to increase air too much because I'm afraid of pushing the fire into the feed tube which is cool right now. I turned down air to 3.75 and got more unburnt coal in the ash bin.

I even manually cranked in some fresh coal to see if unburnt coal would create the dark spot. After several turns without seeing it I figured I'd finally ask for help.

I would appreciate any thoughts on the air/fuel setting. What do you think of the picture. Is the dark area in the picture actually the dark spot I should be looking for? If so, I would have to increase aire much higher than the manual says to make it "a small dark spot". Wouldn't that just make the ash ring too big and run the risk of pushing the fire into the feed tube?

HI Guzzler

I also am a newb to the efm and stokers in general. My ash looks just like yours with maybe a little less black in it but similar for sure.

I also don't seem to get a dark spot. My fire tends to burn off to the right front side of the pot much more than the rear left. my ash ring is generally 1 or 2" with the exception of the left rear (where the air comes in) where it is more like 5".

I can't seem to get my fire centered. still working on it though.

I am running 4 and 4.5 feed and air at the moment.

i'm sure some experts will chime in an help you more!

4/4 is a good baseline, don't try to fine tune the feed/air until the boiler is really running 24/7 for a few days heating your house. What will happen is once the stoker shuts down for the off cycle you'll see the black spot in the center. If you increase the feed or reduce the air the black spot will get bigger, decrease the feed or increase the air and the spot will get smaller. Check some previous posts on the ash ring, I'm not an expert but I think about 2" is good. The goal is to have a cool feed pipe and very, very little unburnt coal in the ash bucket. As far as the uneven fire goes, I'm thinking that the air holes might be plugged up on the right front or there is a hole in the grate on the left rear, or maybe the air pipe isn't all the way in?

As I posted before, in cold weather when there is a big demand for heat, five teeth of feed and four and a half air is a great setting. Sometimes a lesser feed rate the stoker will keep running and won't be able to keep up with the demand. Off center burns in the pot cound mean a bad grate or a plugged up air chamber. Remember you must pull the handle to empty the air chamber every day, don't be gentle with the handle, pull it hard and let it snap back. The best time to do that is when it is running since the air will help blow out the finds. To check the air chamber for build up have some one hold the handle in the open position pull your ash tub out and look up in the open slots to see if there is build up. I usually stick my finger in there and feel around. Pulling the handle is a very important part of correct operations.

Also, check the worm flights for sharpness in the bottom of the firepot. That's no good either.

My caol burns off center too when it is just running short spirts off the timer. I have brand new grates and gaskets. But wait, When the unit runs for a while under a load the coal fire it centered, large and a blue flame over the entire pot minus 2 inches. Just wait and you will see when it runs a while. Good luck.