Coalgun- Puff backs & Explosions

Re: Coalgun- Puff backs & Explosions

PostBy: Bob On: Sun Dec 02, 2012 9:59 pm

Many of us have had puffbacks. I did for 4 years.

I believe the root cause has been indentified in this very long thread--a fire level that is too low.

AHS, at least in the documentation I received, did not note the importance of fire level and did not address how to adjust it. Rather the documentation leads the new owner to believe that draft, recommended SV with the thermograte, and adjustment of the air port on the flapper will prevent puff backs. My experience is that only when I adjusted fire level up--by adjusting SV below the levels recommended by AHS--did puffbacks stop. I made it through the entire heating season last year without a puffback and have not had one this year. So at this point I am inclined to believe that maintaining proper fire level will eliminate puff backs.

But of course generalizing from one's own experience in one specific setting is fraught with the potential for error. YMMV.
Bob
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite

Re: Coalgun- Puff backs & Explosions

PostBy: lsayre On: Sun Dec 02, 2012 10:05 pm

Bob wrote:Many of us have had puffbacks. I did for 4 years.

I believe the root cause has been indentified in this very long thread--a fire level that is too low.

AHS, at least in the documentation I received, did not note the importance of fire level and did not address how to adjust it. Rather the documentation leads the new owner to believe that draft, recommended SV with the thermograte, and adjustment of the air port on the flapper will prevent puff backs. My experience is that only when I adjusted fire level up--by adjusting SV below the levels recommended by AHS--did puffbacks stop. I made it through the entire heating season last year without a puffback and have not had one this year. So at this point I am inclined to believe that maintaining proper fire level will eliminate puff backs.

But of course generalizing from one's own experience in one specific setting is fraught with the potential for error. YMMV.


Bob, what SV and differential are you using?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (It has been fixed!)

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Sun Dec 02, 2012 11:17 pm

I would agree with Bob I experienced the same...have mine set a 110 with a 8 deg. diff...I know of another member who experienced the same also, he runs his at 110 with a 5 deg. diff

fingers crossed though thats for DAM sure
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: macdabs On: Mon Dec 03, 2012 6:11 am

dchartt wrote:I would agree with Bob I experienced the same...have mine set a 110 with a 8 deg. diff...I know of another member who experienced the same also, he runs his at 110 with a 5 deg. diff

fingers crossed though thats for DAM sure

I have tried mine at 124, 120 and 5 diff. ,never below 120. Do you run your site hole open or close?

Mac
macdabs
 
Stoker Coal Boiler: AHS 260
Coal Size/Type: Pea
Other Heating: Pellet,oil
Stove/Furnace Make: AHS
Stove/Furnace Model: S260

Re: Coalgun- Puff backs & Explosions

PostBy: Yanche On: Mon Dec 03, 2012 11:26 am

macdabs wrote: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! :sick: 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! :mad: :mad:

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! :mad: 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!!

Clearly there is a serious issue with the boiler or your installation. An occasional harmless "puff back" is typical, but an explosion-like event is not. You need help in evaluating what's wrong. You say your boiler will ash if the combustion blower is running or not. This is not the typical operation of the AHS boilers I'm familiar with. My is the old timer control, pre-thermo ash, and it will only ash when the combustion blower is running.

Take close look at the schematic diagram in the manual and verify the boiler itself is wired correctly. Look at the flu requirements suggested in the manual and verify you installation meets the specifications and suggestions. Look at the Axeman Anderson installation manual section I posted. It suggest a concentric flue pipe and baro damper installation for a high draft chimney. It's also a much more robust design which directs "puff backs" into the chimney rather than out the barometric damper. Search the forum for my posts on the matter.

To protect yourself I would send a letter to AHS, documenting your problems along with your photographs. Specifically ask for help. Reference past telephone calls, etc. and the fact that they didn't help. Send this registered mail, with signature conformation return receipt required. Address it to the President of the company.

Alternate Heating Systems, LLC
1086 Wayne Avenue
Chambersburg, PA 17201

This should get their attention. You need their help, but you also need to take the steps to protect yourself if there is a liability issue with your boiler.

If they don't help in any serious way, file a complaint with the Greater Chambersburg, Chamber of Commerce. AHS appears to be a member.

Good luck, stay safe and post your experiences here to help others.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Mon Dec 03, 2012 2:52 pm

I run my sight hole open
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: lsayre On: Mon Dec 03, 2012 3:46 pm

dchartt wrote:I run my sight hole open


Ditto here, "over the fire air" sight hole wide open, and my SV at 120 degrees.

No noticable loss of efficiency due to leaving the sight hole wide open. In fact I'm burning less coal this year (to date) with the sight hole wide open then I burned last year during the same time period with it only 1/3 open, despite it being colder this year (so far). I think the coal I'm using this year vs. last has a lot to do with the noticable efficiency improvement.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (It has been fixed!)

Re: Coalgun- Puff backs & Explosions

PostBy: Bob On: Mon Dec 03, 2012 11:27 pm

lsayre wrote:Bob, what SV and differential are you using?


I have SV = 120 and differential = 10.

But I don't think the SV per se is really the key--I think the key is finding a set value for the particular installation that keeps the fire high enough that any gas that is produced is ignited continuously. I think that because of variables such as the ambient air temperature where the boiler is installed, variations in thermocouples, and variations in the location of the theromcouple relative to the fire bed that SV should only be considered an index to be varied to achieved the desired fire level in the burn tube.
Bob
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Tue Dec 04, 2012 1:27 am

ben at ahs is probably hiding under his desk right now (maybe that will get him to chime in)
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: macdabs On: Tue Dec 04, 2012 5:59 am

I spoke with Sean yesterday and Darren should call me back today some time, he was off yesterday. He said they have 1000's of the units out in the field and only have had heard of the puff backs on a hand ful of units :shock: I asked again about the site hole and he said it will not make a differance if the site hole was open or close. He is leaning towards the coal is high in off gasses and possible ash buildup? :? I asked if I should go from an 8'' flue to a 6 '' or change my flue setup and he said no. I think he is leaning towards lowering the SV rate below 120 in small increments. I guess I will wait for a phone call today..
macdabs
 
Stoker Coal Boiler: AHS 260
Coal Size/Type: Pea
Other Heating: Pellet,oil
Stove/Furnace Make: AHS
Stove/Furnace Model: S260

Re: Coalgun- Puff backs & Explosions

PostBy: blrman07 On: Tue Dec 04, 2012 6:15 am

It's the coals fault? It's the ash's fault? Please.....

The Coalgun design is a good design that is in MHO a little bit too tweaky and has been designed to be so efficient that it runs close to that ragged edge. Man has been trying to improve on burning coal since coal was discovered. Technology is wonderful but there are characteristics of every fuel that does not change.

With NG you get too much gas in the gas/air ratio it will not burn right, gas builds up and you will get a boom.
With oil if you get too many oil fumes accumulate from having the wrong or dirty nozzle, you will get a boom.
With any fuel, be it solid, liquid, or gas you get the air to fuel ratio off and you will boom.
With coal if you do not have enough fire when raw coal is introduced, every unit ever made will boom on you.

What is the setting on a Surdiac or a LL or an AHS or Reading handfeds where you won't get booms when putting in raw coal? There is no one setting and the advise that everyone on this board gives is just make sure you have exposed flame to burn the gasses and a bit of over fire air.

This unit is no different other than it looks different. The "laws of coal burning" apply to a Coalgun just like they apply to every other coal burning appliance in use today.

You have to have sufficient flame to ensure that the gasses are burned. Every handfed operator has passed down their VISUAL experience on the amount of flame required to keep this from happening. Why are CoalGun users not doing the same thing? I asked this question before and no one answered.

What is the height of flame where you don't get booms? Not what are the ash settings. What is the height of the flame where you don't get booms?
blrman07
 
Hand Fed Coal Boiler: Bucket a Day
Hand Fed Coal Stove: Vigilant Casting 2310
Baseburners & Antiques: rebuilding a 1906 March Brownback Double Heater, reblacking a UMCO 1920's Pot Belly
Coal Size/Type: Pea/Nut/Wood in the VC and anything that will fit in the Bucket a Day. It's not fussy.

Re: Coalgun- Puff backs & Explosions

PostBy: lsayre On: Tue Dec 04, 2012 6:46 am

blrman07 wrote:What is the height of flame where you don't get booms? Not what are the ash settings. What is the height of the flame where you don't get booms?


The only way to change the height of the flame is via the ash settings, and perhaps to some extent the brand of coal. The AA's and Coal Guns stoke via ashing.

I would ask Darren or Shawn what mods are required to permit ashing only when the fan is running. At least one other forum member has made this mod to his Coal Gun.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (It has been fixed!)

Re: Coalgun- Puff backs & Explosions

PostBy: Freddy On: Tue Dec 04, 2012 7:17 am

macdabs wrote:The mother of all BOOMs!!!! .... One T cap was embedded and wrapped around the floor joist!


Way too scary. I'm glad no one was hurt.
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: Coalgun- Puff backs & Explosions

PostBy: SMITTY On: Tue Dec 04, 2012 2:18 pm

Holy *censored*!! That beats my glass-cracking boom by a large margin! :o :blowup:
SMITTY
 
Stoker Coal Boiler: Patriot Coal - custom built by Jim Dorsey
Hand Fed Coal Stove: Harman Mark III (not currently in use)
Coal Size/Type: Rice / Blaschak anthracite
Other Heating: Oil fired Burnham boiler

Re: Coalgun- Puff backs & Explosions

PostBy: Yanche On: Tue Dec 04, 2012 2:53 pm

It should be obvious to any coal appliance owner that the owners manual you received with your appliance is much less than ideal. The same is true with the AHS Coalguns manual. I do not believe someone new to burning coal can be expected to properly install and operate the Coalgun based on the supplied owners manual. The Coalgun and others suffer from poor installation and instruction manuals. They assume some level of installation or prior coal burning experience. Here we have a new owner who is having considerable difficulty. We can all make suggestions, but none of us are there to observe and evaluate what's wrong. Clearly something is. The "explosion" class of "puff back" is far, far from normal. The owner needs help. Ideally on site help by an experienced person. The owner and AHS collectively need to meet the owners needs. Clearly what has been done so far is unsatisfactory. Each person with a product support problem reacts differently. Some just give up. That has been suggested here. I suggest getting AHS's attention with a registered letter complaint. I find it stunning that a manufacturer with representatives on this forum would not respond to the many, many pages of puff back experiences documented in this thread. What the hell are they waiting for? Do they need the flying baro damper door injure someone. Are they waiting for the liability lawyer's letter?

In my opinion the manual gives little instruction on significance of the burning coal column height and how to adjust it. There is no discussion of adjustments needed because of measurement tolerances. Using a thermocouple measurement system with precise digital set points gives false unit to unit comparisons. A setting that works for the factory or a particular owner may be nowhere near what's required for another. The dynamic range and measurement tolerance is just too great. Think about it. A-A does the control with a rotary bi-metalic dial device. AHS does it with a precise digital device. Do you think the precise numbers have any significant? It's BS. You need to understand the combustion process and how it's changed by raising or lowering the coal height in the "anthratube". None of this is explained in the manual.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea