Coalgun- Puff backs & Explosions

Hopefully the people who have these units in their houses are using heavy-duty and secured smokepipe components as described in those threads.

Mike

The links rob posted was my boiler that blew the chimney apart. It was scary when it happened but I learned a lot and hopefully my mishap has helped others. I'm on storm work repairing people's power but when I get home I have a pic from the puff back that shows one of the rings of the flex 90 stuck a 1/4" into a 2x6. It could have killed someone. Be careful everyone

I don't know about you but I take things out of my house that have a tendency to blow up on a regular basis during normal operation.

I can understand if you do something stupid but this all sounds like Russian roulette to me.

Will I be lucky or unlucky today? The setting numbers worked yesterday but will it blow today?

It would be an interesting experiment if someone were to attach a Wye elbow to their existing exhaust that leads to an expansion tank for the gasses. When a large enough puffback/explosion occurs, a thin diaphram would rupture, opening up the pathway to divert the expanding gas into the expansion tank where they will safely vent back into the chimney under normal atmospheric pressure.

At work on Monday I will draw this idea out on paper and scan the drawing and post it on here. Sounds simple enough, not at all expensive, but would require re-working your existing exhaust.

Whatever happened to "Keep it Simple Stupid?" This isn't unlike 'Stitching a Fart to a Moonbeam'. Good logic, hard to replicate reliably.......ain't I a party pooper. Been there, done that......40 years ago. Ever see the OSHA approved work horse poster? SOAB!

I think this idea is simple Doug, too bad I don't have a CoalGun to experiment with. This idea worked for the boiler on the submarine I was stationed on, whats so different between a nuclear powered boiler and a coal powered boiler?

About 450 million dollars.....
I was just kidding around, and you are correct. The bottom line is to take no shortcuts, buy good quality piping, good grades of bolts, screws, clamps...and don't take a worn Phillips Screwdriver to a Torx Screw Convention.

These puffs backs.....470 posts already, are scary if you don't know what to look for, but panic is NOT the correct response. It will blow piping apart, and I know a few guys who never screw exhaust piping together......
and if you needed a 260 of AHS or AA to prototype, we should talk. I can MAKE either brand have a puff back, and with most hand-feds, too. Most of the guys on the forum can do the same.
Its great to have someone nearly 'soil' themselves, but not really that funny.
Last weekend I was driving around with the leaves gone viewing all the old foundation still standing after the houses were long gone...thinking about all the houses burned over the years......LOTS of them....then along came coal and that all stopped. Sure it was dusty back in the day, but they heated giant old farmhouses with NO insulation and poor windows (by todays standards) and most never got sick. Today we are tighted up so much we have to PAY for an air to air exchanger to get some fresh air....NOT good logic......
Back to one original requirement for coal to be your friend....'It's all about the draft.'

EarthWindandFire wrote:It would be an interesting experiment if someone were to attach a Wye elbow to their existing exhaust that leads to an expansion tank for the gasses. When a large enough puffback/explosion occurs, a thin diaphram would rupture, opening up the pathway to divert the expanding gas into the expansion tank where they will safely vent back into the chimney under normal atmospheric pressure.

At work on Monday I will draw this idea out on paper and scan the drawing and post it on here. Sounds simple enough, not at all expensive, but would require re-working your existing exhaust.

No need to do that. Just install the flue pipe according to the manual, the A-A manual, which also applies to the AHS coalgun. See my previous postings and the comments of others here:

AXEMAN 101 *Class Is In Session!*

and watch your baro fly into space haha!

The mother of all BOOMs!!!! Everything had been working fine with my S260 this heating season. I have burned over 2 ton so far without any problems till I came home from dinner last night. My boiler is in my shop 200 ft from my house.

I opened the door to hear my CO2 detector screaming, the whole 40 x 80 shop filled with the smell of sulfer and smoke! I just finished the boiler room in my shop this summer and have yet to install the door and see my pieces of my baro in the shop area 25 ft from the boiler room! I hit all the openers for three 12'x12' doors for fresh air and rush to the boiler room to see black cool dust every where the tombstone cover laying on the floor with pieces of my baro flue pipe in shreads on the floor! One T cap was embedded and wrapped around the floor joist!

My staineless chimmney cap is even even destroyed. The force of the explosion blew the rivits ot of my Rc baro and all the weights were 20 ft from the boiler in the shop!! the tombstone cover was 4 ft on the floor .
I could not imagine if my 6 year old daughter or myself would have been in the shop at the time this happened! I shoveled all coal out of the hopper and the burn pot and shut the boiler down. I was in my shop three hours before this must have happened and the hopper was 3/4 filled and I heard the boiler cycle and no puffs or even burps since startup this year.
This is beyond dangerous and AHS needs to be addressed before someone is killed. Not to mention the damage or expense caused by the explosion! How can you ever even consider such a device in your basement or house? No expense had been spared on the install of the boiler ever. I even spoke to AHS on the flue pipe and the setup. Sorry for the rant!!

Macdabs, that could be the mother of all Coal Gun puff-backs (explosions). Glad to hear no one was hurt! I wonder of you could get Darren from AHS to come out to your shop and see this?

How tall is your chimney and what are its internal dimensions? What sort of draft do you generally see from it via manometer? Who's coal do you burn, and is it oiled or dry? Were you burning pea or buck? Did you have the small window on the flapper cover open, closed, or partially open? Does your boiler ash only if the fan is running (the UL wired AHS boilers do this, but I believe the non-UL boilers ash whenever the grate temp falls to 10 degrees below the SV, regardless of whether or not the fan is running)? What is your SV temperature set at for ashing?

lsayre wrote: I wonder of you could get Darren from AHS to come out to your shop and see this?

Tell him to bring a truck, that way if he can't find a root cause for the explosion they can give you your money back and take the boiler back with them.

macdabs wrote:This is beyond dangerous and AHS needs to be addressed before someone is killed.

I agree. There are too many other designs that don't blow up to justify running something this dangerous.

The flue is double wall 8''/20 ' with only 5-6' outside the building. The majority of the flue pipe is inside . The building is a 40 ' x80' Corle steel building and I use a digital manometer when I check it and it averages 0.03-.05 depending on the temp outside . My unit is not Ul approved and the grate will ash with the blower on or off. My SV was at 124 and the Hysteria at 5 as Darren suggested. The flapper port hole was closed as Darren suggested since I had it open the last puff back. There was no wind yesterday and the outside temp was probably around 40* . I also burn Blackshak pea coal. There is no rhyme or reason to when a puff back occurs since every time it happens the outside temps or the load on the boiler has been never the same. I could go through 3 tons a coal before it happens again. I honestly feel if AHS does not come up with a solution they will be out of business due to the liability and danger of the unit. No matter how much money you save I could never imagine having such a unit in my home. I would like to know how many S260 units have not have a puffback? I am glad the unit is contained in a block steel building 200 ft from my home. The S260 is not a cheap boiler and the force it takes to cause the damage that occured is beyond dangerous to the point of deadly .

Mac

32 pages and 479 posts.....a few well deserved phone calls on Monday, first thing.