Coalgun- Puff backs & Explosions

Coalgun- Puff backs & Explosions

PostBy: watkinsdr On: Sun Apr 10, 2011 3:00 pm

Hey Fellow Boiler Operators:

I have my new AHS S130 up and running; but, I'm having repeated coal gas voltile explosions! I witnessed one first hand yesterday. I happened just as the boiler fan was shutting down after reaching 180 degree target temperature. I have a manometer on my exhaust; and, I've got really good draft. Any suggestions on what to look for?? What I'm doing wrong???

No sulphur smell, seem to have a good draft, I'm confused.

Many thanks in advance...
Last edited by watkinsdr on Sun Apr 10, 2011 5:22 pm, edited 1 time in total.
watkinsdr
 
Stoker Coal Boiler: AHS S260 Boiler

Re: Help: I Have Repeated Explosions!!

PostBy: crazy4coal On: Sun Apr 10, 2011 4:09 pm

I don't have a AHS S130 but one of my cust does and had his chimmey cap blown off and smoke pipe shot across the garage. He found that the ashing sensor bracket was bent and was letting too much ash build up before it ashed with allows too much fresh coal in. Check your ashing temp setting too.
crazy4coal
 
Stove/Furnace Make: buderus
Stove/Furnace Model: logana

Re: Help: I Have Repeated Explosions!!

PostBy: lsayre On: Sun Apr 10, 2011 4:27 pm

Apparently this is not uncommon. Lots of relevant info can be found here:

http://nepacrossroads.com/googlesearch. ... earch#1205
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Help: I Have Repeated Explosions!!

PostBy: Rob R. On: Sun Apr 10, 2011 5:01 pm

Do you have plenty of make up air available to the boiler room? Is the inspection door clearance set correctly? What is the ashing temperature set at?

Something else to consider is how long the boiler has been running...if it doesn't have any ash in the bottom of the chamber yet then let it run for a while before you get nervous.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Help: I Have Repeated Explosions!!

PostBy: lsayre On: Sun Apr 10, 2011 5:05 pm

Rob (and all), speaking of letting it run awhile, when I install my AHS S-130 I may well face a similar situation with no ash. I often see suggestions that include saving some ash from last years burn to initiate the new years burn cycle. I only have a wood burning stove at present. Can I take some ash from my wood stove and use it to (so to speak) prime the pot?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Help: I Have Repeated Explosions!!

PostBy: watkinsdr On: Sun Apr 10, 2011 5:38 pm

I admittedly have a long horizontal run---exactly 10 feet. But I have a positive slope with the exhaust pipe; and, a good draft of 0.03" to 0.05". I also opened a basement window today to help with draft while the boiler is idling---draft isn't my problem. I'm going to call AHS tomorrow to see what they have to say.
watkinsdr
 
Stoker Coal Boiler: AHS S260 Boiler

Re: Help: I Have Repeated Explosions!!

PostBy: Freddy On: Mon Apr 11, 2011 3:56 am

I'm going to guess you made the same mistake I did when I first fired my Axeman Anderson. Internally it is identical to your AHS. If you started with an empty boiler, and loaded it with coal and lit it, you will have giant booms for 24 or 36 hours. I learned the old timers put in a five gallon pail of ash first, then loaded the coal on top of that ash. Wood ash....not so good, it doesn't allow any airflow through the ash like coal ash does.
Once you get ash established your booms will be a rare event, but if conditions are just right (just wrong?) you might have one now & then. A buddy of mine has an AHS. He has found that putting a paper clip on the view port door and keeping the hopper full helps a lot. The first two years he had a few booms, but this year either one or zero, I can't remember. The paperclip on the door lets some air leak in during burns and that interrupts the methane build up. Yes, every boom occurs just as that door is dropping open after the fan shuts off. I built an anti boom device that fingers the door open for 10 seconds each time the fan tries to shut off. That purges the boiler and prevents booms.
Freddy
 
Stoker Coal Boiler: Axeman Anderson 130 (pea)
Hot Air Coal Stoker Stove: Reading piece o' junk in the barn (rice)
Coal Size/Type: Pea size, Superior, deep mined

Re: Help: I Have Repeated Explosions!!

PostBy: Rob R. On: Mon Apr 11, 2011 8:36 am

lsayre wrote:Rob (and all), speaking of letting it run awhile, when I install my AHS S-130 I may well face a similar situation with no ash. I often see suggestions that include saving some ash from last years burn to initiate the new years burn cycle. I only have a wood burning stove at present. Can I take some ash from my wood stove and use it to (so to speak) prime the pot?


I would skip the wood ash. It might work, but I think it is too powdery and restrictive to airflow. Do you know anyone that burns coal? I'm sure you could find a 5 gallon pail worth of coal ash if you looked hard enough. If not, just fire it up like many do...with an empty pot and fresh coal. Run it long and hard to establish the fire, and prop the inspection door open a little if you have "combustion bumps".
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Help: I Have Repeated Explosions!!

PostBy: watkinsdr On: Mon Apr 11, 2011 10:22 am

On my brand new S130, there's a "small rotating door" on the main flapper door. Right now I have the small rotating door closed---I'm going to open the small door to allow some airflow during the burn cycle. We'll see if this helps... I've also relocated my barometric damper to the far end of my exhaust pipe. Hopefully these two changes will solve the problem. I'm also interested to see how much draft I have today when temperatures hit >70 degrees Fahrenehit with the boiler idling.

Pictures with detail to follow...
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I've also relocated the barometric damper, closing off the near end tee with a cover/cap. The barometric damper will now be at the far end, closer to the flue.
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Last edited by watkinsdr on Mon Apr 11, 2011 11:53 am, edited 4 times in total.
watkinsdr
 
Stoker Coal Boiler: AHS S260 Boiler

Re: Help: I Have Repeated Explosions!!

PostBy: whistlenut On: Mon Apr 11, 2011 10:34 am

This one makes me laugh so hard I fell on the floor! Yes, I've had it happen when my AA's were brand new, because no one ever told me to save some ash (from where?) to cover the ashing plate 3" deep......... and the baro BLASTED off like the space shuttle! (yes, three screws in each joint helps...and is code also.) It added more drama due to the fly ash enjoying it's time for fun also. It gets your attention, and scares the hell out of you and everyone nearby. THIS IS NOT a good time to demo the boiler for friends and family....let it run a few days, get used to it, and make a decision how many alpha males are going to be in your home. If you say 'ONE', that would be the correct answer. You need to learn the tricks of the trade and respect the beast at all times.
Just yesterday I heard about a used AHS130 being fired for the first time..... and the neighbors heard a BOOM.....yup, same one we are talking about. The owner was told by a 'friend' that this could occur at shutdown if it was stoking hard. Anyway, the neighbor walked up to the boiler, grabbed the observation door knob and slide it sideways, peering inside.......do you know what happened yet?.....BOOM! He had sunglasses on fortunately, but he went backwards on his butt.
Be careful...especially when its a new toy. I know Dewey has used the Keystoker Koker for some time,
and I have never heard of a puff from any of their products. :idea: :roll: :lol: :shock:
What is the story with the Koker now?
whistlenut
 
Stoker Coal Boiler: AA130's,260's, AHS130&260's,EFM900,GJ&VanWert
Hand Fed Coal Boiler: Franks Boiler,Itasca415,NYer130,Van Wert
Hot Air Coal Stoker Furnace: Yellow Flame
Hot Air Coal Stoker Stove: Alaska-4,Keystoker-2,
Hand Fed Coal Stove: Alaska,Gibraltor,Keystone,Vc Vigilant 2
Hand Fed Coal Furnace: Van Wert, NYer's, Ford,Jensen.
Coal Size/Type: Rice,Buck,Pea,Nut&Stove
Other Heating: Oil HWBB

Re: Help: I Have Repeated Explosions!!

PostBy: watkinsdr On: Mon Apr 11, 2011 11:47 am

Hey Whistlenut:

This is getting off topic; but, oh well...

The Koker is sitting in my basement all dejected due to being replaced by a shiny new S130 boiler. I plan on completely refurbishing the Koker then: A) Selling it on Craig's List -or- B) Using it to heat my basement/man-cave when it's really cold out. Based on my current (poor) experiences selling stuff on Craig's List, I'll probably be keeping the Koker and direct venting the old girl. She really cranks out the BTUs when called upon. The Koker heated my whole house (basement, 1st, and 2nd floor) plus DHW coil for four years. She's a beast.
watkinsdr
 
Stoker Coal Boiler: AHS S260 Boiler

Re: Help: I Have Repeated Explosions!!

PostBy: Yanche On: Mon Apr 11, 2011 12:32 pm

I've had my share of "puff backs" with my AHS S130. All relate to the didn't do reasons describe by others. Your boiler has the latest inspection door methods to reduce or eliminate the problem. I had my boiler retrofitted with it several years ago. It has eliminated the problem. You need to adjust the small rotating port on the flapper door to allow some over the fire air to be drawn in when the combustion blower is running. Puff backs occur when combustible gases gather above the coal and then find an ignition source. This can occur when the blower is shutting off. By opening the rotating port air port, the over the fire air flow is changed so that some incoming air will clear more of the combustion gases. This helps reduce the amount of gases left when the blower turns off.

The "tombstone" shaped cover also improves over the fire draft when the blower is off. The flapper door is ajar and the column of air in the "tombstone" is heated by the front face of the boiler, it rises and goes into the over the fire area. Ideally this is just enough to direct lingering combustion gases to the natural draft created by your chimney.

In the past I've heard a boom when I was outside and took a quick look at my coal boiler chimney. Saw a smoke ring-like cloud rising from my chimney. It's a AHS salesman feature ... Chimney self cleaning, no need for a chimney sweep. :-)
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: Help: I Have Repeated Explosions!!

PostBy: hophead On: Mon Apr 11, 2011 12:49 pm

Why someone would want a unit with a propensity to explode with enough power to blow baros and stovepipe off is beyond me. Though they may be miserly with coal usage the risk would not seem to be worth it. Suppose it blows when you aren't home or sleeping soundly enough to be oblivious to the noise?I serviced some of these type units for many years and would never be comfortable with one sitting in my cellar. Using coal in both Keystoker and EFM's for over 40 yrs in my home an (explosion) has never happened and should NEVER happen with any automatic system using fossil fuels. :gee:
hophead
 
Stove/Furnace Make: efm520

Re: Help: I Have Repeated Explosions!!

PostBy: Yanche On: Mon Apr 11, 2011 3:34 pm

Well, certainly no one wants such a unit you describe. But on the other hand it's largely caused by operator miss-adjustments. Every appliance has it's quirks, things not it the installation/operators manual. You learn those quirks from experience or hopefully from other owners. Each boiler new or refurbished has pro and cons. Why one selects one over another is a complex human reasoning issue combined with not having all the facts at the time of purchase.

I could ask why would anyone want an auger feed system that could jam and fail? With operator experience you learn not to feed it with rocks. Just like an AHS owner learns the operational issues that cause puff backs and avoids them.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: Help: I Have Repeated Explosions!!

PostBy: lsayre On: Mon Apr 11, 2011 3:53 pm

Would a thread dedicated to cures that experienced operators of the AHS S-130 Coal Gun have found for the puff-back issue make sense?

Is this only an AHS learning curve issue, or does the same issue arise with the same sort of frequency for Axeman-Anderson AA130's as well? If so the dedicated thread would be opened to their input as well.
Last edited by lsayre on Mon Apr 11, 2011 6:14 pm, edited 1 time in total.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)