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Can’t get complete burn with coal

Posted: Sun. Feb. 20, 2022 10:16 am
by alecburk4
I have a Kogen Keystoner boiler and I cannot get a complete burn in it. I have tried 6 different types of coal and the best I can get is about 6hrs before it bridges over and burns out underneath the bridge. I have even tried loading one side with wood soo when it bridges and the wood burns the bridge will collapse but that didn’t work either

Anyone else have this problem? What did you do to solve this?

Re: Can’t get complete burn with coal

Posted: Sun. Feb. 20, 2022 11:24 am
by freetown fred
A, some pix would help. Welcome to the FORUM--lotsa info here. :)

Re: Can’t get complete burn with coal

Posted: Sun. Feb. 20, 2022 1:02 pm
by McGiever
Does it look like this?
Post by jschaefer7406 - Never Burned Coal Before...Advice?

What coal are you burning? Hard or soft?

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 10:16 am
by alecburk4
This is what happens here, I get everything going good, add my coal in layers and get about a 12”-14” mound and then it burns good with good heat for 4-6hrs then it starts losing its heat…. When I go to get it going again there is still 6”-8” of coal left but it is hollow underneath

Water when I fix fire at 11pm is 170°, and by the time I get to it at 5am before work my water is normally down to 90°

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 10:22 am
by alecburk4
It is similar but that Kogen is a hot air furnace and mine is a boiler, mine also has no fire brick inside of it…I’ve tried Pitt nut and pea, Somerset nut, Clearfield nut ROM and now I have Dutch nut

All Bit, the Dutch is definitely the best of them all but still only getting 6hrs of good heat….I put on average 40-60lbs of coal in every time I fix the fire

Has an 8” flue with baro into a 27’ 8x12 chimney. Chimney is almost 11’ above my roof because I added to it after not having good draft last winter. Has sliders in burn door and ash door for air control but main air comes from a thermostatic controller hooked to main air door on back of boiler right under grates. Ashes are taken out 2-3 times daily so ash buildup is not the issue either

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 11:23 am
by McGiever
Slow down the bottom air. Add some top air at the same time.
In between tending give a few pokes from topside to knock down the bridging.

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 12:17 pm
by alecburk4
Normally I run with my bottom slider completely closed and my top air between 1/4-3/8 open.
I let the bottom air be controlled completely with the automatic thermostatic draft control…right now where I have it set with my fire at 165° bottom air is completely closed and as my water cools it automatically opens the draft as it cools off to increase the burn…once it gets back to 165° it closes completely again

My over fire air is always 1/4-3/8 open except when I load I open it fully to get the gasses out soo they don’t blow up.

Shouldn’t the automatic draft keep my fire right around the 165° set point since it automatically opens and closes to control the amount of draft?

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 2:24 pm
by BigBarney
We need a picture of your boiler .

It looks as though there is not enough coal in the firebox to keep a

good fire an be able to collapse the dome as it forms.

Where is the Dutch coal from and what size?

I burn Heritage and Valier coal . House and oversize coal.

The automatic draft can only maintain the fire if you have adequate

coal to be able to rekindle the glowing coals , how often do you

shake down the ash ? How much ash is in the coal that will determine

when you shake down. I shake down each fill 30-100# and get about

10% ash and empty the ash pan 2-2 1/2 days .

BigBarney

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 2:36 pm
by alecburk4
When I fill boiler I fill it too roughly 6” below my baffle that keeps flames from going up the flue, I am using Dutch nut bituminous which is from Shelocta/Indiana area. It is slightly less volatile than Pittsburgh coal but more so than somerset. I was not able to burn anything bigger than nut sized coal as my boiler drafted too much air through it and would overheat. This Dutch nut is pieces from 1/2”-2 1/2”. I really like this coal as it is not very gassy and there’s almost no dust in it.
I probably get 15lb of ash for every day of burning, roughly a 5gal bucket a day of ash.
I shake down 3 times every day, just until I feel pieces of coal beginning to touch my grates then I stop, knock down the bridge and reload in stages making sure each stage is red hot before I put the next layer on.

I will upload some photos when I get home from work today, I am curious how my fire did today with this 50° weather, seems I get alot longer burn times in this warm weather.

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 4:19 pm
by alecburk4
Fire was down to 90°, still 8” of coal left, over fire air was 3/8 open, automatic draft control had draft wide open but it was about burnt out

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 9:38 pm
by BigBarney
If coal is burned out you need much more coal to be able to go the amount of hours

between tending. I keep the water at 190° to 195° so it does not have a long catch-up

time between firings. How many hours do you go between tending the fire,every 8

hours?

It looks like this boiler has very little heat exchange area , so it needs a lot of coal to

provide the heat needed by the house, how many ft² do you have in your house?

BigBarney

Re: Can’t get complete burn with coal

Posted: Mon. Feb. 21, 2022 10:06 pm
by alecburk4
I am gone roughly 10-12 hours for work each day so I need good heat output for at least 8 hours

I am heating a 2700sq ft house and a 900sqft garage but garage only to 50°

It is roughly 22”x18” firebox and I can get coal piled up almost 18” deep, I normally put somewhere between 1-2 5gal buckets worth of coal in it

I am starting to wonder now if maybe my boiler is just too small for my heat load

Re: Can’t get complete burn with coal

Posted: Tue. Mar. 15, 2022 10:28 pm
by Berlin
too small for heat load. 2700'sq house would need min ~80,000 Btu furnace in your climate.

With that boiler design, if it burns completely you'd be at 25-40,000 btu/ hour if your lucky burning 1-2 5 gal buckets in 8 hours. Need bigger boiler.

Re: Can’t get complete burn with coal

Posted: Sun. Nov. 20, 2022 9:20 pm
by Coalblooded
I was just scrolling through posts, is that galvanized pipe for the flue? Thought that was a big no no

Re: Can’t get complete burn with coal

Posted: Mon. Nov. 21, 2022 11:57 am
by carlherrnstein
Coalblooded wrote:
Sun. Nov. 20, 2022 9:20 pm
I was just scrolling through posts, is that galvanized pipe for the flue? Thought that was a big no no
It looks like it is, some people just have a stroke over it. It stinks as the galvanization cooks off, it rusts through quick because it's thinner than black pipe an the biggest thing is that it's not rated to vent a solid fuel appliance. However it will do the job for a while.