killick
Member
I was just wondering if anyone has installed a draft inducer fan on their Econoburn boiler? If so did it remedy the 'back puffing' and reduce smoke when loading?
Earl
Earl
loading/ backfires...
- Thread starter pybyr
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
flyingcow
Minister of Fire
Piker,
After reading your most recent post, it has me wondering if the backpuffing that you described is a separate and different issue than the mini-explosions that some of us have experienced. I've never had anything along the lines of the backpuffing that you described, but for a couple of years did get a few, very infrequent mini-explosion. These were always isolated, singleton events. One of the characteristics of the mini-explosion is the fly ash being blasted out of every unsealed place on the flue piping. There is obviously quite a bit of force required to do this. Since the damper door doesn't get blown open (at least not in my case), the only other path of the explosive power is via the HX tubes. And the only connection from the upper to lower chamber is the gassification nozzle. Because of this, I didn't think the mini-explosions originated in the upper chamber. Could that much force be transmitted from the upper to lower chamber through the relatively small nozzle, flood and compress the lower chamber, and pass up the tubes that quickly and powerfully? Normally the non-gassified, combustible gas travels from the lower chamber up the tubes, unless something holds up the flow, such as a partial blockage, or perhaps a period of downdraft from inversion. I had been thinking that the lower chamber was getting filled with combustible gas during momentary periods of non-gassification. Then, when the torch is lit ... kaboom (sort of like an engine without the compression). It's fairly easy to imagine an explosion in the lower chamber driving everything right up the 4 tubes and into the flue. Do you think what I've described above is possible - i.e. your backpuffing being separate and distinct from the some of the other mini-explosions?
After reading your most recent post, it has me wondering if the backpuffing that you described is a separate and different issue than the mini-explosions that some of us have experienced. I've never had anything along the lines of the backpuffing that you described, but for a couple of years did get a few, very infrequent mini-explosion. These were always isolated, singleton events. One of the characteristics of the mini-explosion is the fly ash being blasted out of every unsealed place on the flue piping. There is obviously quite a bit of force required to do this. Since the damper door doesn't get blown open (at least not in my case), the only other path of the explosive power is via the HX tubes. And the only connection from the upper to lower chamber is the gassification nozzle. Because of this, I didn't think the mini-explosions originated in the upper chamber. Could that much force be transmitted from the upper to lower chamber through the relatively small nozzle, flood and compress the lower chamber, and pass up the tubes that quickly and powerfully? Normally the non-gassified, combustible gas travels from the lower chamber up the tubes, unless something holds up the flow, such as a partial blockage, or perhaps a period of downdraft from inversion. I had been thinking that the lower chamber was getting filled with combustible gas during momentary periods of non-gassification. Then, when the torch is lit ... kaboom (sort of like an engine without the compression). It's fairly easy to imagine an explosion in the lower chamber driving everything right up the 4 tubes and into the flue. Do you think what I've described above is possible - i.e. your backpuffing being separate and distinct from the some of the other mini-explosions?
My experience has been the same as willworkforwood -- I am not aware of any instance in which my EBW 150 has had any sudden pressure events except immediately after putting in a new load of wood on top of a partially burned bed of wood and then re-closing the loading door and the top chamber flue flap.
[I have that situation a lot less now that I have a better sense of when it'll be just glowing coals].
[I have that situation a lot less now that I have a better sense of when it'll be just glowing coals].
E.W. said:
Draft inducers can help reduce smoke spillage into the home, but on a boiler where the stack exits below the top of the upper chamber door it's difficult to get rid of all of it. I have never run a draft inducer while the boiler was gasifying in an attempt to reduce backpuffing, so I don't know if this will help or not.
cheers
willworkforwood said:
I too once wondered if the the explosions were coming from the bottom... but nothing that I have seen indicates that is the case. I don't believe there to be enough oxygen down there in a "lump sum" to cause a violent explosion. Nor is there generally dense unburnt woodgas. I have actually had backpuffs occur on our old boiler with the bypass damper open. I have also witnessed a violent backpuff actually blow the bypass damper open on a boiler that had it's locking mechanism fall out of adjustment and wasn't locking as tight as it should. If the bulk of the pressure was being built in the lower chamber and heat exchanger tubes, you would not be blowing the bypass damper open... you would actually be blowing it shut from the heat exchanger side. I have even peeked into the bottom chamber door during a backpuffing fit to see what's going on in the lower chamber... the refractory can be white hot in the bottom with a wicked torch beating down when an explosion occurs up top, blowing smoke, ash and coals down through the nozzle and ash and smoke back out through the primary air ports and fan. When a backpuff happens, you can see the front blower plate flex from the pressure. If you open the upper chamber door on a boiler that is going through one of these fits, you will find dense smoke followed by a giant puff of fire as fresh air enters the firebox... and singed facial hair and/or flesh. A backpuff is basically the same thing that happens when you open the upper door on a smoke filled firebox with a hot coal bed... fresh air rolls in all at once and the woodgas ignites extremely rapidly... the difference is, the door is shut and there is no where for the expansive gasses to go but back out through the fan or down through the narrow nozzle... it's like a high caliber backpuff I guess.
If the explosions happened in the lower chamber, i would think you might see fire coming out of the barometric check, not just smoke and ash. I will concede that you're thoughts on how an explosion could happen in the lower chamber seem logical... and I wouldn't rule this out as a possibility... but I don't have any first hand experiences that would indicate that is where they are coming from.
cheers
- Status
