Anti Puff Back Device for AA... Isn't Working

An often overlooked item is the amount of available air in the boiler room. Matthaus touched on the issue of boiler room pressure. By adding a few square inches of outside air to your boiler room, many puff backs can be avoided. I haven't had any since adding outside air louvres (about 40 sq. inches free area).

The mechanical code calls for considerable room space for combustion air. If that isn't available then air vents to other indoor spaces is the solution. In the event that cannot be done, add outside air vents.

If your boiler is in a confined space (defined by the mechanical code as having less than 50 cubic feet of space per 1000BTU/h of rated input of all installed appliances) then you need more air.

The input on an Axeman 130-M is 130000/.84 (the fuel efficiency rating)= 154761. 155*50=7738 cu ft. In a room with an 8ft ceiling the dimensions could not be less than 967 sq ft or 31'X31' without additional air communication with indoor spaces or additional outdoor air. Outdoor air shall be supplied via openings to the outdoors sized at 1cu in. of free area per 4000btu/h per rated input of all appliances in the room. In a confined space without communicating vents to other rooms, the required size opening to the outdoors is 38 sq in.

This will add some coolness to the floor but the room remains at 70* while the outdoor temp is in the teens.

BIG BEAM wrote:Like I said before SUPERIOR coal is like runing the family car on nitro-methanol. This weekend I was playing with superior coal in my hand fed.I usually open the load door about 10 mins after loading and it goes woof and I'm done.This time I went to the bathroom with a magizine(dumb move) and 15 or so mins latter BOOM from the cellar.I went downstairs and the baro that has 1 screw in it and the factory clamp was at a 45*angle.Now that was a puff back.

Seems like your getting this down to a science.I think it's just a matter of timing in your case.(how much air and for how long) Good luck.
DON

Try Cracking the loading door after filling the stove it will wash the gas up the chimney shut the loading door once the new coal lights You will not have anymore booms You still would keep the ash door open with the loading door cracked
open until the fresh coal starts to burn.

Yeah J.C. I'll do that from now on.
DON

Freddy wrote:I tried the 9 ball trick.... the dog took the balls & burried them out back!

Rats! I knew that was too easy! After re-reading the whole thread, I can't come up with an idea better than what you are doing, Freddy. I agree you just have to get the electronics right. But here's one more idea anyway:

The problem on a hand-fed stove is more at the replenishing of a fire. That is, when you load new coal onto the burning bed, the heat drives off a lot of gases from the new coal that may not ignite right away. Eventually the gases can build up and cause the boom. One way to avoid that is by giving it LOTS of air through the regular inlet, which leans out the mixture so it doesn't ignite. Eventually the mixture gets rich enough that the gases DO ignite, but there's enough air going through that it tends to be a gradual ignition rather than a boom. Is there any way to do that with your stoker? The equivalent might be, to taper off the combustion air gradually rather than just cut it off all at once.

AA style stokers do not run out of coal, they burn continually and re-kindle the flames with very aggressive combustion fan action (the fan is 9" in diameter and turns fast enough to create one hell uv a flame!

Hey Freddy, if your relay is a double pole, then run the power that triggers the relay thru one set of normally closed contacts. Should keep the relay from resetting. Scott

stokerscot wrote:run the power that triggers the relay thru one set of normally closed contacts

Yaaaa, but then it doesn't get the signal to start the sequence. It's like...it has to get the signal once, but not the second time. The original idea was.... each time the boiler shuts off, it actuate the finger and runs another ten seconds. The problem is, after the ten seconds, the boiler shuts off, then it acutautes. Arghhhhh! I think one of those.... what do they call those things that let power go in one direction, but not the other? Yaaaaa, it needs one of those. *smile*

A diode???

Freddy wrote:

stokerscot wrote:run the power that triggers the relay thru one set of normally closed contacts

Yaaaa, but then it doesn't get the signal to start the sequence. It's like...it has to get the signal once, but not the second time. The original idea was.... each time the boiler shuts off, it actuate the finger and runs another ten seconds. The problem is, after the ten seconds, the boiler shuts off, then it acutautes. Arghhhhh! I think one of those.... what do they call those things that let power go in one direction, but not the other? Yaaaaa, it needs one of those. *smile*

Yaaa, it doesn't get the signal to start the sequence the second time because the relay contact is now open Yaa. Scott

DIODE! Yaaaa, gotta get me one o' dem. Or not LOL. I'll keep it on my brain & if I find more time to goof off I'll mess with it.

Puff-back in the AA can be caused by dirty or unwashed coal. Is your coal washed?

My coal is spanky clean! It really is, very little dust or fines. As mentioned, I haven't had a puffback since day two. I really think the booms had to do with too much fresh coal in the burn chamber. Now that it has a good ash bed and the coal is dribbled in as needed it doesn't do it. The whole idea of the anti puff back device is so I can close the 5/8" air hole over the fire. I do think my Superior coal may have more voltiles than other coal so it could be an issue if I closed the hole now. I just don't want to try it!

My AA doesn't go boom at all. No horizontal sections on the stove pipe. Somewhat pitched. Have a good draft, chimney goes straight through center of the 2 story house. One thing I didn't do was read the manual when buying the stove pipe. I bought 5" pipe and elbows, 5" field control baro, 5"-6 increaser, 6"-7" increaser then into thimble. I didn't put the pipe halfway into the baro.

The brand of coal has nothing to do with puff back. Any coal that you stick in a hand fed stove will do the same thing
all coal puts off gases when it is burning the gases will build up on a fresh load of coal and if you do not leave them gases
wash up the chimney as soon as fresh air and a open flame hits the gases you will have a boom It is Operator error
nothing more. With a AA Or AHS You will have that boom happend with any coal if you do not get the gases out or if you
have to much fresh air coming up threw the bottom of the fire chamber.On a fresh load of coal on a new fire leave it
burn for a 1 to 1 1/2 hr before you start ashing & adding new coal. Give it time to burn off the gases and catch the coal real good you will not have any booms . also put enough coal ash on the ash try to stop all of that fresh air from going up

the bottom fire chamber and pushing the gas up to the top where the flames are. Or put somthing in the veiwing door
to keep it cracked open until the gases wash up the chimney. On hand fed stove if you do not have over the fire air knobs or vents then Just crack the loading door to wash the gases up the chimney until the new coal catches you still keep the ash door open once the new coal lights then shut loading door wait a few minutes then shut the ash door no
booms.You can look at the AA & AHS boilers as Big auto hand fed boiler they feed the coal from the top & ash from the bottom with a big fan on the end to pull the fire & air across the top of the fire chamber taking the heat into the water

jacket area heating the water up. and then taking the hot gases up the flue on the other side to the chimney. Pretty simple when you think about it .But like with a hand fed stove if you ash to soon or to often you will loose fresh coal in you ashes. You must leave them have a good burn so the coal has a chance to burn before you ash them or add new coal . And like a hand fed stove make sure you have the coal bed full to the top when burning . Also you need a good draft to take the gases away up the chimney .

Hey Freddy,
As far as I know I've never had a puff-back with my new AA, although I did have some flames make it up to the top of the feed tube where the 3 nuts hold on the cover (evidenced by the burned off red paint). Since you haven't had one since the first couple days, why don't you plug the hole and see what happens? Maybe your problem is all ready gone??????????