Buck not burning completely

I see. I have my feed at 2 turns out from full. I was running full feed, and still wasn't pushing red coals off and had an inch or so of ash on a full burn. I backed it out 2 turns, and opened the restrictor plate just a little bit for more air. My draft is set between -.02 and -.03. I have the chimney model, actually it is a direct vent model that I converted to chimney by taking off the DV blower on the exhaust. I called Keystoker before buying it used and they said to hook it to a chimney just remove that assembly and the stove is exactly the same. So anyway, that's where i'm at. I'm thinking my feeder cam might be a bit worn (I had another thread on this) and I might replace that over the summer if it's not hard to do. What exactly would increasing my draft to -.04 or -.05 do other than suck more heat out the stove? Does it make for better combustion?

The only thing increasing the draft would do is to make your idle fire more reliable, that is the fire would not try to go out due to lack of air being pulled through the grate and coal bed.

If you have the smaller 'idle blower' on your stoker assembly, this is the smaller fan that runs 24/7, then there is no need to worry about increasing the draft above what your current settings are.

Greg L

Hi Greg...concerning the increased draft....there IS a point at which a stronger draft will pull more heat out of the stove/boiler..agreed?
Do you know of a way of determining what that point is? Ie..perhaps placing a thermometer prior to and after the baro? Of course you want the one after the baro to read cooler...but I don't know of any goal for a desired differential between the two...or if its even a practical exercise...

You are 100% correct. That's why I said that his current .02-.03" should be fine if he has the idle fan running..
I think you could do an interesting experiment, by measuring flue pipe temperatures and compare them to uncontrolled draft, and outside temps and winds.
It would be valid for your chimney, house, stoker, etc.. and would transfer to other instalations only in general terms.

Greg L.

Greg, if I hold the baro closed on my EFM's flue pipe I can watch the needle in the stack thermometer (right at the flue collar, 5' upwind from the baro) start to climb. I haven't held it closed to see just how much of a difference it makes, but it jumped 50 degrees pretty quickly.

That may not be sucking more heat out as much as not pulling in cool air. It is a tough thing to quantify I think.

Kevin

It is due to the increased volume of air passing through the fire, aka "excess air"; just like an oil burner.

I understand the theory, it is a matter of where you are checking the temp. To get a full understanding, it would have to be checked at several places. I am sure this has been done and that is why there are recommendations for flue draft and over fire draft. But one thermometer does not tell the tale. I will follow the recommended drafts and take what I get for efficiency.

Kevin

KLook wrote:That may not be sucking more heat out as much as not pulling in cool air. It is a tough thing to quantify I think.

Kevin

Yes, I think you're both correct.

Ok..this thread has led me back to something that has perplexed me for some time...I have a permanent Dwyer manometer measuring draft at the exhaust flue about 15" from the stove exit...the flue then quickly transitions to a tee (bottom used for clean out), and then there is my baro in the verticle flue...my draft reading with full fire is always about. 035...all good so far...
the thing that seems odd to me is this: I have an over the fire Dwyer measuring that draft too...at 'idle', the reading bounces around at .04-.045!...and the if the boiler calls for heat and the fire ramps up, that over the fire reading jumps right down to about. 025...
This seems crazy! I would think at idle the OTF reading should be lower and then higher with a full fire...the way it is reading now, at idle my OTF draft is stronger than my flue draft..does this make sense???

stoker_RI wrote:.the way it is reading now, at idle my OTF draft is stronger than my flue draft..does this make sense???

No, it doesn't make sense.

Calibrate your manometers--- or at least determine the nominal difference between them by simultaneously sampling the same draft point, i.e., two side by side holes in the flue pipe.

WNY wrote:My keystoker always has some unburnt coal whether using buck or rice, sometimes it rides on top or along the burn grates sides and never burns, you may always get a little bit of unburnt.

I keep my intake blower about 1/2 open (where the factory mark is set at). I keep it at .04 with Direct Vent.

Going on 6+ years with it and never had a problem.

Typcially, 4 Turns out is a good starting point for these, then adjust accordingly (1/2 turn in or out). I think I am at 5 turns out and 4 or 5 Pins on the timer every 10 mins.

Question on the feeder... when it's feeding coal and the lobe is rotating mine has lag or some time when the bar is not moving in between pushing and pulling (about 12 or 13 seconds between strokes). Is this normal? I still suspect my cam is worn, because I can have my feed maxed out and turn the thermostat all the way up to feed continuous for hours and still have a good 1.5 to 2 inches of ash at the end of my grate (with restrictor plate at factory 1/2 open). If I were to back the screw out 4 or 5 turns I wouldn't get enough heat for the upstairs.
I did have to replace the nylon screws that adjust the pusher bar to keep it moving straight because they were melted off when I bought the stove, so obviously the previous owner had some sort of problem (the stove was hooked up as direct vent). As I said in one of my posts this is a direct vent stove but I have removed the fan assembly to hook it to my chimney.

I contacted Keystoker and they said based on what I said about the latency between strokes of the stoker, the feeder cam is likely worn or the nylon screws also. I did replace the screws before winter so it can't be that. Once I'v shut it down for the spring i'll tear it apart again and see about replacing the cam.