Coal on the Top of the Pile Does Not Seem Completely Burnt

Hi All, I'm new to this forum and new to coal burning, but I'm really looking forward to telling PP&L to go, well, you know, when they take off their rate caps.

I just hooked up a Harman Magnum stove and I am working on the tuning. So far things are going ok (I owe some of that already to this forum). However, it seems like the the coal that's on the top of the burn pile does not get burned as complete as the coal that's at the bottom of the pile (closest to the grate). The coal at the bottom seems to turn to tender ash, while pieces of coal from the top of the pile keep their shape and if you break one open, you might see what looks like unburnt coal at the center. This is with pieces taken right off the very edge before they fall into the ash pan.

Does this indicate that one or more of my parameters need to be adjusted? FYI, I'm using bagged coal from Sones in Bloomsburg and I have no idea where it comes from or it's quality. It is dry, however.

Thanks

I have a Harman VF3000 boiler.
the stoker in it is the same as in your stove.
That partially burnt coal is normal.
you will see this when the stove is idling alot.
when it is cranking out heat when it is cold outside you will see the ash fully burnt.

This is the reason I don't burn coal for DHW during the summer because
the boiler would be idling most of the time and the coal is only partially burnt.
so I burn oil for DHW in the summer

Yes this seemed to happen during long idle periods. I slightly reduced the feed rate and increased the combustion blower duty cycle and that helped quite a bit. Now some of the coal still has its original shape but it's very crumbly and the inside is not shiny black unburnt coal.

Yes, increasing the time the blower runs does burn the coal better, BUT....I feel that even though the coal is burnt better, you are also blowing the extra heat from the coal up the chimney so my feeling is you don't gain much doing that.

I had the same problem with mine. I unplugged the combustion blower from the Harman timers and plugged it directly into an outlet to run 24/7. In my mind, this emulates what a hand-fed stove does - feeds air to the coal all the time. Since the coal doesn't get a chance to "rest" during the off cycle, it burns better.

Harman Magnum Stoker Timer Settings/Setup

most of the other stoves run the Combustion blower 100% plugged directly into an outlet. Mine burns pretty complete all the way thru, even on Idle.

Doesnt that make it overheat? I have the VF 3000 and I have been playing with it to get it to idle better without dumping heat. I am also seeing poor burns but figured it was the price of idling.

Kevin

I plugged the combustion fan motor into the distribution fan control that has a timer.I then set the timer to 10 minutes.The combustion fan will keep blowing for ten minutes after the stoker stops pushing coal on the off time.The fan will still blow while stoking as normal. My summer settings are,4 minutes on time,twelve minutes off time and the combustion blower running 10 minutes after stoking controlled by the distribution blower timer.The blower motor gets a 2 minute rest every cycle.I get a more complete burn with it set up this way. My feed is cut way back so I don't get overheats.170 degree water is the hottest I seen it all summer. I do scrape the ash off the grates twice a day because of the low feed rate not wanting to push them off effectively.I use a small dry wall finishing paddle to do it.

I have been playing around with a pinball machine fan blowing into the squirrel cage opening on the idle time too and that worked pretty good but I added cold air induction and there was to much stuff in the way.

hey steveyrock... how you doin good buddy !!??

I was wondering how much coal I would use if I ran my VF3000 on coal all summer.

but since I also have a 120gal hot water solar system I figured the boiler would be idling all summer except rainy days.
so I changed the VF3000 to burn oil in april and I will change it back to coal around Oct 15 .
I used about 80 gallons of oil april-oct.

How much coal do you use per day when it is mostly idling???

here is the link to the hot water solar system I have:
http://www.altestore.com/store/Solar-Water-Heater ... tors/p157/

watch out fot the shipping charges... thats where they really soak ya.

Hi Syncmaster
I have been useing 9 to 12 lbs a day.I would say 10 lbs is the average with just two of us useing hot water.We do a couple loads of white wash a week wich will take alot of hot water.I get my coal for 160.00 a ton and a ton lasts over 5 months for DHW.I used 4 and a third ton total from september 1rst, 08 to september 1rst ,09 .
I like that solar system but the 4000.00 dollar investment would take hmmm lets see 160.00 a ton times 25 is 4000.00, it would take 25 yrs to pay for itself and I still would need to suppliment it on cloudy days.
When I got to stop burning coal I will look into solar.I am lucky to live 30 miles from the coal regions and can pick my own up at the breakers and wish everyone else could do the same.

i also have a Harman mag stoker, I have also noticed the unburnt coal when idling a lot. I too have experimented with plugging the combustion blower into a outlet so the combustion blower will be on continuously, but have found that all you are doing is sending the excess heat up your chimney. it is my opinion that the amount of unburnt coal is really minimal and if you are so inclinded you could load the grate with the unburnt coal for a second burn, but running the combustion blower continuiously is just wasting energy.