Coalgun- Puff backs & Explosions

My Harmony ash is pronouncedly red throughout. My Blaschak and Stockton only had occasional red spots interspersed amongst the gray ash.

Would this type/brand of boiler have less puff backs if it were running hard vs idling? Maybe these boilers operate best when under load and are not suited for light loads and moderate temperatures.

Dewey, did you have as many puff backs when you had the S130, I know that unit was too small and you replaced it with the S260?

Based on my observations from reading these posts and others over the course of several years, and maybe being unbiased since I have no boiler, it seems that I would take the following preventative actions, as a minimum, if I were to buy one.

A). Have a custom one-piece exhaust made from the same alloy-steel tubing used for heavy-duty vehicle exhaust systems welded into place. This way, it would be impossible that a puff back could blow apart the boilers exhaust resulting in spilled and deadly CO build-up in a home.

B). Install a Photohelic that would activate a fan and an alarm system, drawing in fresh outside air, if the draft were to fall below a set point. This could prevent CO poisoning which we all value far more than saving money on heating our homes.

I actually believe that the Whoomps come after long and hard runs combined with heavy ashing cycles. In my opinion both are required. But then again, I did not have this issue with Blaschak, so I believe that the 3 requisites for a puff-back are volatile coal, a hard run of the fan cycle, and heavy ashing.

This talk about the volatiles is interesting...I have always preferred coal with a high volatile content for its easy starting and ability to hold a fire.

Rob R. wrote:This talk about the volatiles is interesting...I have always preferred coal with a high volatile content for its easy starting and ability to hold a fire.

Rob, when you burned Lehigh, did it cause any problems due to its low volatility?

I didn't have any problems with it, but I only burned it in hand-fired equipment. I do remember that it was a little more sensitive to the "rules" of starting and maintaining an anthracite fire in a hand-fed unit. i.e. the coal bed must be 6" deep or more, you must cover the entire grate before starting a fire so no air can bypass the coal, and you must maintain a steady draft at all times.

I'm convinced this puff-back problem with AHS boilers is really easy to solve. You simply need to ensure there's an open flame to burn volatiles off before they can accumulate. Keeping the fire high enough in the sight tube area resolves this part of the problem; but, due to varying load, weather, etc., it's a pain in the butt to keep changing the PLC "set variable" to keep the fire high in the sight tube area.

Again, the existing AHS design is an open loop control system. Their design really needs to be changed to a closed loop control system; with, a second thermocouple monitoring (and keeping) the fire high in the sight tube area---but not so high you burn up into the storage hopper.

I had puff-backs with my S130---they were simply much smaller.

Gas volatiles occur naturally when when solid fuels transition through their kindling point and combust---this is a completely normal chemical process. No volatiles---no combustion---no heat. It's nonsense to contemplate and compare white ash, red ash, deep mined, strip mined, etc.

I run my ahs130 without a controller only the timer based grate shaker. As I posted some time ago as long as the fire is as high as I dare go there is no bangs.Now last spring after I cleaned out the hopper and all ash I decided to try something different. I bought a dwyer controller and thermocouple with my specs and put the thermocouple in the coal feed tube enclosed in a secondary protective sheath with the tip exposed. I can adjust the amount of travel of the t-couple in the feed tube just before the coal exits into the fire pot. This will give me some idea what kind of temps in that area. I plan to set the control to cooling cycle to turn on grate when temp goes to my high set value. The grate will run until the temp drops as fresh coal enters. I can then determine my diff. setting. This year for the first half of the heating season I'll be using the grate timer and only monitoring the temps with a log at which my fire is optimum with the controller readout. If I'm satisfied I'll switch over to the controller to operate the grate. With this setup it should also keep the fire from climbing into feed tube but still keep the fire high where I want it. watkinsdr mentioned a second t-couple. I 'm sure that would work too. We'll see what happens. Thanks

Sounds like a interesting experiment there *pete6500*.

Let us know what you find out.

wonder if my ahs130 will take me into space and perhaps land me on the moon?

dchartt wrote:wonder if my ahs130 will take me into space and perhaps land me on the moon?

Doubtful. In my experience at least, puffbacks are way overrated. They are more like occasional brief whooshes. And with a bit of adjustment, you can make them all but completely go away.

Your mileage may vary though. Obviously the experiences of some of the forum members have been much more than just a mild whoosh.

dchartt wrote:wonder if my ahs130 will take me into space and perhaps land me on the moon?

Doubtful, but your baro might make it into a low orbit.

mine did last year

Haven't had time to read this thread but my AA130 has been blowing my baro across my garage for the last 6 months. Start happening when I switched from pea to buck? Today the puff back shook the house I took the plug out of the sight hole cover as quoted from Axeman when you switch to buck. I think I need to drill more holes in it???? I'll read more of this thread to try to catch up to what you guys are talking about.................be back soon. MATT

I'm happy not to have any experience in this area, but I'm concerned that what you're describing seems to have the potential to rupture the smokepipe. The joints on universal elbows are often pretty flimsy; a boom that shoots a baro across a garage seems like it could blow apart an elbow. Does that type of damage ever occur?

Mike