Burner combustion fan speed for best burn/efficiency?

Good morning all,
I gotsa question for all you experienced guys: I have an Alaska carpet style stoker stove, a Kast Console 85kbtu. What is the best way to get the most heat for the least amount of coal? It would seem to me that to get the hottest fire and the most complete coal burn out of the least amount of coal would be to run the burner combustion fan on it's highest setting and simply adjust the carpet's feed rate to regulate the stove heat output. This is what I learned to do years ago when using a small blacksmiths coal burner to work with iron forming. This is how I'm running the stove now too.
I have the old Alaska single reostat control on the burner. I run it at full speed and simply adjust the carpet feed rate to increase or lower the stove's heat output. (I also run a steady .02-.03" of draft unless it gets really windy out, in which case the barometric damper just can't spill enough air into the flue to keep it that low).
I have a separate variable speed rotary switch for the room warm air blower so I'm only asking about getting the best burn out of the burner itself.

It seems to me that blowing the most amount of air up through the coal will make burn it the hottest and most completely rather than slowing down the combustion fan and the carpet feed rate together like the reostat control actually does.

Am I correct in this thinking?
Please tell me if I am misguided on applying this theory to my coal stove and why/how it might be more efficient to regulate the carpet and the burner fan speed together or if there is a better way for me to get the most heat out of the coal.
(I'm burning up to 120lbs a day in this stove but I'm heating close to 3300 sq ft of old 1841 farm house with what I think is coal with a lot of shale in it maybe. I'm using "Reading" brand bagged coal)

Thanks much!

Both my Hyfire and Keystoker run the combustion fan continuously full speed. There is no adjustment in speed. However, The stoker is regulated by the timers and/or thermostat. So, the coal does sit on the burn plate for a certain period of time to burn up and then gets pushed off. (3 mins on/10 mins off)

The keystoker has a small plate over the intake of the fan to adjust it a bit, but I haven't really seen much difference in coal combustion. It will raise/lower the idle temps.

My hyfire I rewired from reohstats to the CoalTrol and it maintains the burn rates based on temps and adjusts the feed accordingly.

Hi Paco, you are doing just exactly right.. Keeping the fan running will give the coal the most air and the greatest opportunity to burn fully.

If you are getting some black, unburnt 'coal' in your ash, it probably is shale or reclaimed coal from culm piles [refuse piles] at the breaker.

My experience with Bagged Reading coal is that it had lots of shale, wood sticks, and some rocks... not very good coal.. For bagged coal, Blaschak is more expensive, but has a better quality product... Try to find a few bags of Blaschak and see how it burns in your stove...

My recommendation is to buy bulk coal, an get it yourself.. This way you can control which breaker you get it from, and get more consistant quality, and save some money.. Most bulk coal can be bought for around $140/ton, The most expensive is Blaschak bulk, $160/ton at the breaker... I had good luck with Blaschak, but didn't feel the 'need' to pay more when as good or better coal was available for less $$ a few miles away..

So Keep burning and running the combustion fan the way you are, it is the most effecient way to burn the coal fully.

Hope this helps.. Greg L

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There's a fine line between the feed, fan and combustion

If you feed too slow with full speed fan, it will have good combustion, but may cake or clink up. Too fast, incomplete burn and wasting fuel.

You have to adjust it accordingly to get a good burn and good heat. Especially with the rehostat only control system.

You could add a Timer box (http://www.electricsuppliesonline.com/intishracyti.html) to control the feed rate (XX mins ON/XX mins Off), that would elminate it from being fed constantly and possibly give you a better burn and save fuel. That is what most of the newer stoves have for the idle mode to keep a small fire burning when heat is not called for.

I thought most stokers ran the combustion fan full on all the time? Mine does (LL) and my friend's Alaskas do also.

Great, I made sense then! I couldn't understand, and I still can't, why Alaska had the reostat control hooked to the burner air/carpet feed motor along with everything else. The reostat controlers simply adjust everything together: the burner blower/carpet feed motor, the burner motor cooling fan and the warm air blower. I'm wondering how Alaska's newer Auto-Heat controller operates. Does it control feed rate independently of the combustion fan and the warm air blower, etc.?

I'm now also convinced that the Reading bag coal is pretty much junk and I'm paying for a lot of stone. Makes sense of why I'm going through 100lbs or more a day on this stove and why I have to empty the ash pan so much too. The other stove I had didn't make as much ash and the ash didn't have what appeared to be so much unburned coal in it... well in the old stove I was using bulk coal that I'd had and it obviously was much better coal with less stone it.
Time to try some other suppliers and brands!

At least I've got some extra gravel on the driveway from all the gravel.. err.. I mean ash...

Thanks guys!

The 'old style' stokers didn't run the combustion fan full time, they relied on chimney draft to pull air through the coal bed/ grate/fan to keep the fire burning... This resulted in a less complete burn of the coal, since the temperature dropped when the fan stopped.. and when the weather is warm, the draft would be minimal, and fires went out.. With the fan running full time, the fire stays lit, the fire burns hotter, getting the most from partially burnt coal or poor coal.

Greg L

"I'm now also convinced that the Reading bag coal is pretty much junk and I'm paying for a lot of stone. Makes sense of why I'm going through 100lbs or more a day on this stove and why I have to empty the ash pan so much too. The other stove I had didn't make as much ash and the ash didn't have what appeared to be so much unburned coal in it... well in the old stove I was using bulk coal that I'd had and it obviously was much better coal with less stone it.
Time to try some other suppliers and brands!

At least I've got some extra gravel on the driveway from all the gravel.. err.. I mean ash... "

I agree, I fill my hopper and empty the ash pan every day. I have 2 different sources of my coal. Some days I burn 150 pounds of Reading bagged coal and the ash pan is 95% full and consists of metal pieces about the size of large marbles and black stones that are not combustible (shale I guess), other days with all things being equal temperature wise I'll burn 100 pounds of the other stuff (unknown brand) and the ash pan is 1/2 full and the ashes are more granola looking and mostly all tannish pink color. The kicker is some of the bags of Reading are great, some literally look like a bag of unwashed gravel. I bet the Reading dealers are getting complaints and that they will pressure the company to replace the screens or something in the near future. They wouldn't have been in business so long selling an inferior grade of coal for the same price as their competitors. It doesn't take too many customers finding molten Master Locks in their ash pan to decide that they are burning garbage.

HeresPaco wrote: I couldn't understand, and I still can't, why Alaska had the reostat control hooked to the burner air/carpet feed motor along with everything else. The reostat controlers simply adjust everything together:
Thanks guys!

I have read back thru the thread I might have missed something but it appears your dealing with a stove that uses the older Tri Burner system in this set up just one motor operates the feed carpet off a top drive shaft and the combustion fan off the bottom shaft, the stoves the other posters are using for a comparison use 2 separate motors for the jobs . Alaska has since changed the type of feed they use now and I am sure now utilize 2 motors also along with eliminating the Carpet Feed in favor of a rotating cam type block .

The type you are using is not obsolete it is still used on the Reading Line of stoves and parts are available from Alaska and Reading, it is not the preferred system among many stove aficionados . If you are interested in souping it up a bit there is a member here Mattaus who has been successful converting it over to a separate blower configuration and he is always eager to share his know how and expertise, PM him or perhaps he will spot this thread .

On the topic of continues Fan operation I have a Harman and do not run fan continuously, a while back a poster Dutchman did an unscientific experiment with his Harman and found no real advantage between the two methods of operation, Harman to this day does not run the fan all the time so I just follow the way the factory specifies as you could do also, its up to you, be aware that if you are going to change the way the factory tells you to do something it is best to set aside some time ( a day or Two ) that you can be close to the stove and monitor it in the event something goes wrong or needs fine tuning .

I think I may revisit the continuous fan idea when the outside temps start to rise and the stove spends much more time idling there may definitely be an advantage here then, but for now with the big house and cold weather unburned coal ain't an issue that babies cookin right along and is on more than its ever off.

Coalstoves, you are right about my stoves being the tri-burner style.

Hey Paco, you have figured out how to make the current configuration run the best it can, keeping the stoker motor (and hence fan) speed up will ensure enough combustion air, then as you figured out just use the stroke to limit the coal feed. As stated by others there is so much a thing as too much air, when your stove is burning look at the flames, they should be nice and blue and barely above the fire at min stroke and at least 12" above the fire at full stroke.

As coalstoves said I do have some tips on changing the mode of operation to be more in keeping with current stove designs. The debate over running the combustion fan 24/7 Vs only when the stoker motor runs will wage till we are all dead and buried. I will leave that to you to decide, once you remove the plastic squirrel cage blower and install a separate fan you have unlimited potential to get more performance and less unburned coal out of the stove. I have some extras if you would like to purchase one.

The other item which makes the biggest difference is getting rid of all those rheostats and install a Coal-Trol with Tstat. I personally use the PB1-CM1 model with TS2 Tstat on my stoves. I have been burning an Alaska Kast Console in my house with the separate combustion fan controlled by the Coal-Trol for over a year and a half. I am now currently burning a Harman in my house controlled by the same Coal-Trol and am not getting any better performance than I did with the Alaska.

I also agree with you, find better coal but that is just me.

The separate combustion fan seems to be the way to go. I don't even have the stove burning yet and I'm already thinking of ways to burn it better!

Wood'nCoal wrote:The separate combustion fan seems to be the way to go. I don't even have the stove burning yet and I'm already thinking of ways to burn it better!

I'd try it stock just to see how well it works about 2 years ago me and a friend rebuilt one to put in their autobody shop but there was no way his Dad was gona have a coal fire with all the paint fumes so we sold it on eBay and I never got a chance to even see it burn . It was like yours but no RED doors .

PS
I thought you’d have that lit by now

coalstoves wrote:

Wood'nCoal wrote:The separate combustion fan seems to be the way to go. I don't even have the stove burning yet and I'm already thinking of ways to burn it better!

I'd try it stock just to see how well it works about 2 years ago me and a friend rebuilt one to put in their autobody shop but there was no way his Dad was gona have a coal fire with all the paint fumes so we sold it on eBay and I never got a chance to even see it burn . It was like yours but no RED doors .

PS
I thought you’d have that lit by now

So did I, but I was busy with work this week and didn't have a chance to get the stove pipes. I'm hoping to round everything up tomorrow morning and get it done this weekend. The cellar is about 52 degrees.

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?