AHS S130 Coalgun- Puffbacks & Explosions

lsayre wrote:I wonder if leaving the 5/8" hole open all of the time impacts the overall efficiency of these boilers?

Don't wonder measure it.

Years ago forum member Berlin posted a formula for Anthracite Coal,

"high quality anthracite coal empirical formula: C240H90O4NS"

Quoted from his post:

Coal Vs Wood Pellets

So what you need is a chemistry experiment. You combine air, (standard atmosphere formula) + burning anthracite and measure the output flue gases. Adjust air as needed.

Measure the flue gases with Bacharach CO2 and O2 FYRITE instruments. That plus gas temperature will let you optimize air inlet for maximum efficiency.

In case you are not familiar with them, here's a description right out of the Bacharach Fyrite owners manual:

The FYRITE employs the well-known “Orsat” method of volumetric analysis involving chemical absorption of a sample gas, such as carbon dioxide or oxygen. The reagent used to absorb carbon dioxide (CO2) is potassium hydroxide (dyed red), and chromous chloride (blue) is the absorbent for oxygen (O2). The unique feature of the FYRITE is that the absorbing fluid is also used as the indicating fluid so that one vessel takes the place of both measuring burette and absorption pipette.

Please post you results here.

Ouch, the combined CO2 and O2 Kits plus the required reagents top $1,000. A bit much.

They are sometimes on Ebay. There are not many bidders because many don't know what they are. I bought an entire CO2 and O2 kit for $75 directly from the seller after no one bid on it. The reagents can't be easily shipped so you have to buy them at your local HVAC wholesaler. Mine had to get NOS transferred from other locations in the company. While I was initially thrilled to have such a measurement capability I never used it. Too much effort to understand how to use it and the realization there wasn't much I could adjust to change the combustion any way.

Yanche, do you operate yours with the 5/8" hole covered or uncovered? This question is also open to all owners of AHS or AA 130's.

lsayre wrote:Yanche, do you operate yours with the 5/8" hole covered or uncovered? This question is also open to all owners of AHS or AA 130's.

No such animal on my 1948 axeman fire view port door.

lsayre wrote:Yanche, do you operate yours with the 5/8" hole covered or uncovered? This question is also open to all owners of AHS or AA 130's.

I have the disk on the flapper door rotated so about 50% of the possible open area is exposed.

Yanche wrote:

lsayre wrote:Yanche, do you operate yours with the 5/8" hole covered or uncovered? This question is also open to all owners of AHS or AA 130's.

I have the disk on the flapper door rotated so about 50% of the possible open area is exposed.

Thanks! Very helpful information.

695 views and you have them scared to death!!!!!!!!!!!!!!!!!

It is no big deal, guys, part of the learning curve.............play with fire, you could get burned....or not.

Thinking about the questions from Isayer and my answers I'd like to put it all in perspective. No matter how much air comes in the flapper door when the blower is on couldn't possibly make much difference in the operational efficiency of the boiler. The combustion blower is likely sized to provide 20% or more excess air over what's required for coal combustion. So that little opening in the flapper door, either by the latest factory rotatory shutter or a simple paper clip holding the flapper door ajar couldn't possibly change the total combustion air much and certainly couldn't lower it so much that there would be an inadequate amount for coal combustion. As I see it tweaking the air flow at the flapper door is more about changing air flow above the burning coal so that combustion gases don't accumulate and create a "puff back" condition.

As "whistlenut" says, "no big deal. Hand fire boilers and stoves can have the same "puff back" conditions. All my comments apply equally to AHS and A-A boilers.

I've been running my ahs130 going on 4 years. I too have had some booms. I can tell you exactly when mine occur. If I keep the coal fire just up to the bottom of the sight tube and set my timer to keep it there during the whole season, then everything is fine. But, if the temp outside goes high and I don't slow the the grate down, the the fire drops too far below the sight tube into the pot then I get the booms. During those warm days which are very humid and low pressure sets in, it is a must for me to keep the fire real close to the bottom of the sight tube. Apparently if the fire drops lower in the firepot then too much fresh coal is laid on top from the funnel and that is when I get the boom. When I want to bring up the fire higher in the pot I turn off the grate and restart it when the coal fire is where I explained. Also my draft is good and I considered the thermo ash system but i'm not sure if that will cure the booms. I hope this might help as this forum has great info!

Hey Pete, welcome to the FORUM--thanx for that info.

pete6500 wrote:I've been running my ahs130 going on 4 years. I too have had some booms. I can tell you exactly when mine occur. If I keep the coal fire just up to the bottom of the sight tube and set my timer to keep it there during the whole season, then everything is fine. But, if the temp outside goes high and I don't slow the the grate down, the the fire drops too far below the sight tube into the pot then I get the booms. During those warm days which are very humid and low pressure sets in, it is a must for me to keep the fire real close to the bottom of the sight tube. Apparently if the fire drops lower in the firepot then too much fresh coal is laid on top from the funnel and that is when I get the boom. When I want to bring up the fire higher in the pot I turn off the grate and restart it when the coal fire is where I explained. Also my draft is good and I considered the thermo ash system but i'm not sure if that will cure the booms. I hope this might help as this forum has great info!

I am in my fifth year with an AHS 130 and have had a continuing problem with booms sufficent to damage/destroy the barometric damper.

I have my boiler in an out building that I have maintained at 54-55 degrees. I also have historically operated the ash control at 130. This resulted in the fire below the bottom of the sight tube.

This year I am experimenting with maintaining the building at 60-61 and with the ash control at 120 and have yet to have a boom. These changes raise the level of the fire in the column of coal with the result that there is less coal above the fire to generate gases.

So I think I have identified that the temperature of the room where the boiler is located can affect the frequency of booms. I think I have also identified that setting the ashing control to a lower temperature than recommended by AHS may reduce the frequency of booms. I think it is likely there is a connection between the temperature of the room and the ash control temperature setting.

To put it another way I think pete6500 has offered a really important insight--that the level of the burning coal in the column is critical to avoiding booms.

I've had my Thermo Ash Control set at 125 degrees for about a week now. No booms at any setting here (so far at least). But do you get a more complete burn to fine ash at 120 degrees than at 130 degrees for the thermo ash monitor control set-point?

In speaking with Jeff Gingerich he was convinced that the puff-back trouble is generally related to both the quality of the coal and the draft. I told him that I was leaving the little 3/4" rotating port hole cover that is within the sight tube cover open and he said that I should fully close it unless my coal is really bad or my draft is poor. I haven't gotten up the nerve to close it fully yet, but after speaking with him I did close it down about 2/3 of the way. Being a rookie I have no way of knowing what is good anthracite and what is not. My draft at idle and with no wind outside generally sits right at 0.03", but during warmer spells (temps in the mid 60's outside) I've seen it on occasion at closer to 0.02". At night when it is colder outside my baro damper is generally opening to keep the draft at 0.04", even during idle.

Did the Coal Guns made 5 years and more ago have the 3/4" port hole in the sight tube cover plate? Do Axeman's have it?

I am not sure what year the Axeman Anderson boilers started having a hole in the inspection port cover, but I find it interesting that the 1953 Bureau of Mines report that Yanche posted on this site mentions that a hole had to be drilled in the cover of the boiler inspection port to burn buckwheat coal satisfactorily.

lsayre wrote: Did the Coal Guns made 5 years and more ago have the 3/4" port hole in the sight tube cover plate? Do Axeman's have it?

My coal gun was produced in 2007 and it has the adjustable port hole. I have operated with it full open but continued, until this season, to have problems with booms.

As I posted above my thinking now is that the level of the fire in the column of coal is a critical factor--that if the fire is too low the amount of coal above the fire is producing large amounts of gas that contributes to the boom. With the thermo ash control the way to adjust the level of the fire in the column is to adjust the temperature setting--the higher the temperature setting the lower the fire is in the column.

Also--based on my experience with the boiler in an outbuilding I think there is an interaction with the temperature of the supply air--the cooler the supply air the lower the thermo ash control should be set.

My experience is that with the thermo ash control set at 120 I am getting more complete burning of the coal--there is more very fine ash and the ash is lighter than when I was burning at higher control settings.