loading/ backfires...

[pybyr]

OK, although I have been steeping myself in the collective wisdom of the Boiler Room for 2/3 of a year, my first burn was only mid last week, so my learning curve on the "practice" is steeper than on the theory (what's that wonderful quip - "In theory, there is no difference between theory and practice. But, in practice, there is.")

I am fantastically happy with my unit (Econoburn 150) even though there is more to do on the final configuration of the install, as well as more to learn as to how to run it at its best.

one of the things that I am running into is that, sometimes, once I have secondary combustion going, but pause the unit to load a piece or two of wood, and then go to close the damper and turn the blower on again, it does a "backfire" -- there's a "rooowhoooomp" sound and you can hear the barometeric damper clang, and also hear pressure push back out through the intake fan.

I typically power down the fan, and then open the bypass door as the fan is winding down to zero RPMs; then I load the wood. Then, to power back up, I have tried both starting the fan first and then soon after, closing the bypass, and also the reverse.

I will sometimes briefly open the lower door to let some updraft and flame through the new wood, as this seems to get the whole thing into a happy resumption of gasification sooner than if I just throw new wood in and recommence the burn

Barometric damper is set to 0.03 " water column, per Econoburn specs of more than 0.02 and less than 0.05

Chimney can draw like crazy if it is not being held back by the barometric damper- so I do not think I am dealing with any problem with a restriction in the flue.

Thanks, everyone, as always.

Trevor

 

[LeonMSPT]

I suspect it's a situation where there is plenty of combustible gas, and heat, and air.... suddenly there is an interruption in the air. Gas accumulates, and then the air is restored... a slower transition from full air to no air and back might mitigate this... otherwise, unless it's shooting smoke out into the space you're living in and standing in, and not damaging anything, don't worry about it...

Better yet... bring your wife down, and when it goes, “rooowhoooomp” , scream, "RUN!" and take off up the stairs...

 

[lawandorder]

Every now and again I get the same thing with my solo 40. I dont think its a problem just enough gas building up in the box so when i close the damper i get a mini explosion. I try to avoid it but sometimes it still happens.

 

[Dave T]

Leon is right I have an EKO and had small puffing ,on the EKO a manual chimney damper is opened to divert smoke directly to the chimney and after loading i would close the damper with a little authority to seat it because of soot around the damper..Now I am slowly closing the damper till it just about fully closed I delay there for a few seconds then close it tightly,this method has eliminated the backpuffing right after loading..GREAT TO HEAR YOUR UP AND RUNNIN PBYR best of luck..Dave

 

[Dave T]

Leon is right I have an EKO and had small puffing ,on the EKO a manual chimney damper is opened to divert smoke directly to the chimney and after loading i would close the damper with a little authority to seat it because of soot around the damper..Now I am slowly closing the damper till it just about fully closed I delay there for a few seconds then close it tightly,this method has eliminated the backpuffing right after loading..GREAT TO HEAR YOUR UP AND RUNNIN PYBYR best of luck..Dave
Sorry for the double post!!

 

[Nofossil]

My solution to a lot of issues including this one is Nofossil's first law of wood gasification, meat smoking, and turkey roasting:

Don't mess with it.


In this case, that means 'don't open the door when the fire is cranking'. I've found that a small amount of planning can eliminate any need to open the primary door except for refueling, and then only when it's down to a bed of coals. This virtually eliminates puffbacks, smoke in the house, and other assorted gremlins.

 

[pybyr]

Better yet... bring your wife down, and when it goes, “rooowhoooomp” , scream, "RUN!" and take off up the stairs...

I don't have a wife- merely an ex wife-

and, at the moment, not even a girlfriend; the last girlfriend was jealous of the time I was spending on the boiler... (she'd agreed in concept with the importance of being able to stay warm without going broke, and get off the fossil fuel situation - but the realities of a big project were off-putting to her)

 

[pybyr]

My solution to a lot of issues including this one is Nofossil's first law of wood gasification, meat smoking, and turkey roasting:

Don't mess with it.


In this case, that means 'don't open the door when the fire is cranking'. I've found that a small amount of planning can eliminate any need to open the primary door except for refueling, and then only when it's down to a bed of coals. This virtually eliminates puffbacks, smoke in the house, and other assorted gremlins.

Thanks NoFo-- I completely agree with and aim to eventually arrive at such an approach. At the moment, though, with the "Phase I/ Mark I" install (no storage yet), and with being new to getting a sense of how much wood it will use at what rate under various loads, I do need to check it some as I learn.

 

[hoth2oguy]

"scream "RUN!" and take off up the stairs.." has got me cracked up! Thanks for the LOL chuckle!

 

[LeonMSPT]

I drive those around me a little crazy from time to time... I can walk up and tell you your hind end is on fire, and you'll sniff and reach back to check.

 

[wantstoburnwood]

I get lots of these bangs or back drafts. Especially when the boiler is cold and I light it. Turning on the fan can be quite an experience. I usually run the fan for a few minutes before lighting the fire to kinda warm up the flue and that seems to help , then after the fire is light I turn on the fan and close the damper . After your boiler is dried out completely it will work much better ( it took days for mine to dry). Keep me posted

 

[pybyr]

Thanks everyone- some of the detonations have been impressive enough that I wanted to ask to be sure, because I don't suddenly want to have a kaboom and have my stack pipe from the boiler to chimney all torn open at the seams, right as the gasification gets going really well....

ironically, since I asked the question, it hasn't done it again....

 

[NNYorker]

My solution to a lot of issues including this one is Nofossil's first law of wood gasification, meat smoking, and turkey roasting:

Don't mess with it.


In this case, that means 'don't open the door when the fire is cranking'. I've found that a small amount of planning can eliminate any need to open the primary door except for refueling, and then only when it's down to a bed of coals. This virtually eliminates puffbacks, smoke in the house, and other assorted gremlins.

Thanks NoFo-- I completely agree with and aim to eventually arrive at such an approach. At the moment, though, with the "Phase I/ Mark I" install (no storage yet), and with being new to getting a sense of how much wood it will use at what rate under various loads, I do need to check it some as I learn.

Trevor--Posts here have helped me learn to burn with the Eco. I have split my wood to roughly the size of a deck of cards(end cross section),some might be the size of a children's Skip-Bo deck(for the overnight burn). Each split roughly equates to a 1 hr. burn---6 splits=6 hr. burn. Whatever size wood you have,throw in some splits--use your judgement/guesstimate on a burn time--You'll get it pretty quickly,of course weather,load,etc. will affect it too.

Here is my load routine- 1. Open bypass 1st and let fan keep running for 10-15 sec.-decrease set temp so fan shuts off

If fan is not running-increase set temp so fan runs then decrease to shut fan off

2. Open lower door- you shouldn't have to open it too far 1-2"

3. Get your wood/poker--depending on draft the boiler will start chugging if you have a good bed of coals--Nozzle area will glow red

4. Open upper door ever so slightly-just a crack-or you'll probably get a face full of smoke

5.With a decent draft upper chamber should clear up pretty quickly-load new wood

6. Close upper door

7.Increase set temp. so fan ramps up for 10-20 sec.-close lower door

8.Close bypass

Good luck-can't wait for storage stories..........

 

[chuck172]

After experiencing these mini-explosions from time to time, I can't emphasize enough how important it is to put a screw in each of those black pipe joints.

 

[Tree farmer]

For what it's worth my wife says the boiler is my mistress and claims I'm going to see her every time I go in the basement, I told her "if only it was that easy".

Not sure how the econoburn is setup but with the eko after loading and closing the bypass damper I usually count to ten then hit the start fan button, when I just turn it on it on without waiting it explodes. Like nofossil says, the less you open, load and fool around the better it is, I only open mine twice a day and load.

 

[wantstoburnwood]

Gee I just got a bang like no other . Blew the cleanout cover right off the bottom of my flue. It is only about 12 inches below the smoke pipe but it really scared me . How do you other gassifiers avoid the bangs?

 

[Fred61]

I have gotten the explosions when firing up the boiler, going from regular updraft fire to gassification mode. I tried different sequences such as closing the lower door then starting fan then close bypass damper or start fan then close door, etc. I don't know if any have been the answer so I use any combination and do it as fast as possible in any sequence but do it fast in the blink of an eye. Probably comical if anyone was watching. Don't get it on reload, probably because I don't shut off the fan. If there are still hot coals gassing there is usually enough draft to keep sucking the fire down the nozzle.

 

[killick]

My EB 150 does the same thing at times. Kind of made me jump the first few but now I just ignore it. Being new to this gassification business I am guilty of checking the fire and loading too often but I am learning to leave it alone and fill once the previous load has burned to hot coals. I am really impressed with the heat this unit can pump out. Sold the old wood boiler, a New York Thermal, to a fellow this morning and the oil boiler hasn't run yet. Sweet!

Earl

 

[NNYorker]

After experiencing these mini-explosions from time to time, I can't emphasize enough how important it is to put a screw in each of those black pipe joints.

Read this post from the beginning after a new post---I had a kaboom about a month ago --no screws on my pretty tight fitting barometric damper off the bottom tee-- I now own a new BD secured with screws. The old one blasted off and hit the 1 1/4" copper--now residing in the dump recycle bin.

 

[willworkforwood]

Can't offer anything about other boilers, but here's my cut on the Econoburn. I had also been getting these occasionally in the past 2 years, but nothing at all this year. With a linkage mod this Summer, I've been able to brush the heat tubes every few weeks, removing the accumulated ash deposits (impacted, not fly ash). In addition to that, I make sure to regularly remove the piles of ash that tend to accumulate at that back of the boiler under the tubes. I suspect that some combination of these piles, along with extra ash or creosote deposits in the tubes restricts the flow just enough to allow an amount of gas to accumulate in the chamber that can provide enough fuel to result in a mini explosion. For the EB owners who get this, you might want to poke the back of the cleanout chamber to make sure all of the deposits have dropped down, and then pull them out during ash removal. Or, you can just let the mini explosions do the cleanout job for you ;-P

 

[pybyr]

I haven't been getting the big ka-booms this year, but the pivot shaft on my barometric damper is a bit bent at the pivot points from past events (it still pivots, and still holds calibration, so no big deal)

I have sometimes gotten little "rhoomps" but nothing too dramatic

One of my main annoyances about these events is that they seem to force fly ash back out of small joint openings of the flue pipe (even though I have sealed most of those with high-temp silicone) (or out the barometric damper), and it then forms a fine coating all over everything nearby.

 

[ISeeDeadBTUs]

How does a two year old thread get resurrected?? hh:

 

[NNYorker]

Can't offer anything about other boilers, but here's my cut on the Econoburn. I had also been getting these occasionally in the past 2 years, but nothing at all this year. With a linkage mod this Summer, I've been able to brush the heat tubes every few weeks, removing the accumulated ash deposits (impacted, not fly ash). In addition to that, I make sure to regularly remove the piles of ash that tend to accumulate at that back of the boiler under the tubes. I suspect that some combination of these piles, along with extra ash or creosote deposits in the tubes restricts the flow just enough to allow an amount of gas to accumulate in the chamber that can provide enough fuel to result in a mini explosion. For the EB owners who get this, you might want to poke the back of the cleanout chamber to make sure all of the deposits have dropped down, and then pull them out during ash removal. Or, you can just let the mini explosions do the cleanout job for you ;-P

How did you do your linkage mod? I'm all for anything to make that job easier.

 

[willworkforwood]

How did you do your linkage mod? I'm all for anything to make that job easier.

First thing to say is that my 150 and your 100 may not be constructed the same - you would need to find out about that before doing anything. I removed the entire turbulator linkage assembly, up to but not including the round turb shaker cross bar. I substituted 4 sections of chain, one attached to each turb. The chains are also attached at the other end in pairs to 2 bolts; and the bolts are attached to the shaker cross bar. So the turbs now hang suspended from the chain, instead of being hard-linked to the bar. There is just enough clearance (1/2") to allow the damper door to open. The bolts can be easily undone via the top plate, with the turb shaker handle in the max up position. And then the turbs, chain, and bolts can also be pulled up and out of the tubes. I went around the block a few times with Dale on this, and he naturally did not give a factory approval - the best he could do was say he thought it should work ok. So far, so good - I've removed the top plate, pulled the turbs, and brushed out the tubes 4 times so far with no issues. The cleanout takes around an hour, including all ash removal from the flue and chambers. Now, there is one very important thing to understand about this. Because the "hard" linkage is gone, and the turbs are attached only by the chain, if the tubes are allowed to become clogged up with heavy ash or creosote, the turbs would probably hang up in the tube (after shaking the lever). That would in turn block the damper door from fully opening. So, this mod should only be done by someone who will be diligent about cleaning the tubes. As an extra precaution, I only shake the turb lever with an empty boiler, just in case a turb ever hung up (I could pop the top plate and push it back down). I'm pleased with the results so far, but won't call it a success until after a full season. Also, the turb linkage naturally needs to be fully disassembled, back plate off, yada, yada, yada (you know the drill), in order to make this switch. If you are still interested after all of these warnings, I can send pics and the detailed specs.

 

[Piker]

I call this issue "backpuffing." There are several factors involved and different units are effected differently.

I essence, when the upper chamber of a downdraft is full of smoke, pockets of fresh air can accumulate from the primary air supply tubes. These pockets of fresh air can mix rapidly with the dense smoke near the coal bed and cause rather violent explosions - inside the upper chamber. Different factors like how the primary air enters the upper chamber, the ratio of firebox size to nozzle size, and overall restriction of the exhaust gasses I think play a role. Also moisture content... on the Econoburn boilers, it seems like the drier the wood, the worse the backpuffing is. The 100's and 150's can backpuff a moderate amount... the 200's can drive a man to drink they backpuff so much. It's been an issue we've had to deal with ourselves when we ran a 200 in our home, and also for a few of our customers with in house installs. The bad part about it, it doesn't seem to be something you can work around. Backpuffing "fits" can start midway through a load of wood and go for several minutes, with perhaps a dozen of these backpuffs at varying degrees of intensity.

My experiences with this line and backpuffing have driven me to the point where I will not install a barometric check on another wood boiler ever again. Like others, I have seen the weighted flap on a barometric damper be destroyed and blown across the room along with fly ash and copious amounts of smoke. It's not a pretty sight. The barometric checks also allow cool air into the chimney, generating condensation and creosote in the chimneys of boilers that are run without thermal storage. The problem with not running a barometric check on an econoburn is that the flaps on the fans are not weighted enough to prevent draw through the boiler when the fan is off... and draft from the chimney can freely pull enough fresh air through the boiler to keep it smoldering buy not gasifying... cutting efficiency and generating creosote where it's not supposed to be. I have had a few customers who have modified their econoburn boilers with weights on the fan flap behind the blower mount so they can remove the barometric check, and have actually had really really good results. I shouldn't publicly condone this practice cause it goes against how the manufacturer requires that their boiler's be installed... but it does work, and from what I have seen, very well.

I don't have enough of the new Scandtec Solo Plus boilers in the field to know for sure how they react to the backpuffing issue, but we do have all 3 sizes out there now... thus far, no complaints from backpuffing, and i have never witnessed a backpuff while commissioning a boiler. Not saying it couldn't happen, because I think with a lot of small pieces of dry wood it could... but because the boilers are not required to have a barometric damper installed, I am not too worried if I do get a backpuff or two. It's possible that the larger and less restrictive nozzles (The nozzle on a 30kw solo plus is actually larger than the nozzle on a EBW200), the lower cfm of combustion air flowing through the boiler, the way the air fans out into the upper chamber differently, along with the huge heat exchangers are what's making the difference. The 100's and 150's each have 4 2" tubes... the 200's have 6 2" tubes. On the solo plus boilers, the 30, 40 and 60kw versions have 6, 9 and 12 tubes each... all 3".

It is of note that I have never had any sort of backpuff or huffing incident with the Froling. I would think that other draft induction models would also be free from this type of nuissance.

cheers