Chimney questions

[warno]

The cheap part of modifications I can accomplish, easy on the other hand that's another story. anything I do to "modify" from here until I shut down is going to require me crawling in my on top of my 100+ degree refractory surrounded by a jacket of 150+ degree water. it's hot in there is what I'm getting at. not that I can't handle the task, it just won't be "easy".

Later today I'll draw up another sketch of a different idea I've been kicking around for you guys to review. it will be a natural draft setup with a smoke channel above the fire with air introduced into it.

 

[maple1]

How do the gases get out in that last pic? Hard to tell, do they drop below that round looking cross piece thing? And does it have a bypass damper? Guessing not?

 

[TCaldwell]

Don't know if you have the room in the burn chamber to put a second one above it, but could you add on to the back( garn style)

 

[warno]

How do the gases get out in that last pic? Hard to tell, do they drop below that round looking cross piece thing? And does it have a bypass damper? Guessing not?

The gases in the secondary branch come out through the holes that I circled. if you are referring to the gasses leaving the firebox they must drop below the water cooled baffle, then go into the heat exchanger. I do not have a bypass damper it's just air in flue gases out.

Don't know if you have the room in the burn chamber to put a second one above it, but could you add on to the back( garn style)

it would be easier to build down then it would up or back. building down I can avoid the water jacket.

 

[Fred61]

The cheap part of modifications I can accomplish, easy on the other hand that's another story. anything I do to "modify" from here until I shut down is going to require me crawling in my on top of my 100+ degree refractory surrounded by a jacket of 150+ degree water. it's hot in there is what I'm getting at. not that I can't handle the task, it just won't be "easy".

Later today I'll draw up another sketch of a different idea I've been kicking around for you guys to review. it will be a natural draft setup with a smoke channel above the fire with air introduced into it.

About the temperature of a crock pot. Don't forget to bring the carrots in with you!

 

[brenndatomu]

would it be wise to move my secondary branch out over top of the fire?

I would. Move it up higher in the firebox and then forward too (toward the loading door) which probably means going lengthwise instead of crossways

About the temperature of a crock pot. Don't forget to bring the carrots in with you!

 

[warno]

I would. Move it up higher in the firebox and then forward too (toward the loading door) which probably means going lengthwise instead of crossways

Ok that's easy enough to do. I'll try that out.

 

[STIHLY DAN]

What is the heat exchanger heating? The outside of the water jacket?

 

[warno]

In this picture you can see the heat exchanger above the fire box

And here is the water jacket walls going on.

The heat exchanger is like the tubes in a gasifier boiler going through the water. but instead of pipes I used a big box.

 

[Bootstrap]

I hate to say it, but a considerable reduction in smoke might not happen. Without some kind of reburn prior to the heat exchanger I don't see how. Insulating the fire box better would improve, and increasing stack height might help get more of that smoke away from the area. Those two things might be enough to please everyone.

 

[warno]

So I did some modifications to my secondary air piping today. I have positive draft pulling air into the inlet of the pipe but still no secondary flames, not even alittle. I seal the fire box opening with a piece of plywood with a hole drilled to see inside and the secondary piping inside is glowing red but no flame coming from the holes. so its drawing air and it's hot but no flames. I'm wondering if the air is having to travel too far too get to the holes. I mean the air had to flow all the way forward them to the back of my fire grate then up into the pipe with exit holes. it's almost 6 feet of pipe before it can exit out the holes inside the fire box. should I shorten this distance? would that help anything?

Some pics of the new branch with exit holes

 

[brenndatomu]

I still have a bad feeling that the "cold" water cooled firebox wall right there is killing the temps that it normally takes (1200*) to make the magic happen. I wonder if you could stuff a piece of 1/2" ceramic insulation blanket above the tubes temporarily to test this theory...or maybe some rockwool (roxul) type material

 

[Fred61]

I think you're just blowing air into smoke that is not hot enough to ignite. In fact your primary fire might not be hot enough to heat the top of the fire even if your secondary air was directed within an inch of the primary fire.

Is there a way you could build a ceramic tunnel to house your primary fire with a nozzle on top and direct primary air to the center of the blaze so that it burns like you were blowing on an ember to start a fire so that it glows like a cigar. In other words, very little air. That would send super heated gas through the nozzle and perhaps re-ignite above the tunnel. Only a small amount of secondary air would be needed as a large amount of air would have a cooling effect. It also should be directed to the nozzle area.

 

[warno]

I'll put a stainless steel plate over top of the tubes to protect them from above and test the theory again.

I should add that when I was trying to test the secondary flames i shut down the inducer fan and opened my ash pan door a crack to get natrual draft induction.

 

[brenndatomu]

I'll put a stainless steel plate over top of the tubes to protect them from above and test the theory again.

I'm sure that will help but I dunno if it will be enough really...stainless is gonna have a very low R value compared to the 1/2" - 1" thick ceramic insulation board that many/most secondary burn stoves use in the top of their fireboxes.
Easy enough to try I guess...

 

[JohnDolz]

I hate to say it, but a considerable reduction in smoke might not happen. Without some kind of reburn prior to the heat exchanger I don't see how. Insulating the fire box better would improve, and increasing stack height might help get more of that smoke away from the area. Those two things might be enough to please everyone.

I know there is a lot of concern around keeping the neighbors happy, keep in mind that they may not appreciate looking out the window and seeing a stack sticking way up in the air. The smoke only seems to be an issue when you fire up, if you create an eyesore you have a year round issue to deal with.

 

[warno]

I know there is a lot of concern around keeping the neighbors happy, keep in mind that they may not appreciate looking out the window and seeing a stack sticking way up in the air. The smoke only seems to be an issue when you fire up, if you create an eyesore you have a year round issue to deal with.

I had that thought as well. I'm trying to get things better with the stack I have at the moment because materials for trail and error are cheaper then $75 per 3 feet of stack pipe.

 

[Coal Reaper]

let to the party here!

Curious, how is the stainless plate working? Its above your secondary air, correct? I was thinking that would help is I read through this thread. Stainless will hold up to the heat well and you can let fly ash accumulate on top of it to insulate against the cold walls of the firebox.

Have you tried raking all your coals to the back before reloading and starting your fire from there? Doing that and stacking your wood tight might get you a nice 'cigar' burn starting from the back where your primary air enters allowing it to get hot as fast as possible.

I would try to keep as high of temps as possible where the burn is in the firebox and let the heat exchanger transfer the BTUs to the water.

Where is your fan located?

 

[warno]

I haven't had much time to mess with things as of lately. I need to relocate my primary air ducting still and add the stainless plate above the air tubes. I just haven't had much time to do it since getting my new job.

 

[brenndatomu]

new job

Congrats!

 

[warno]

Congrats!

Thank you. It's going great as well.

 

[STIHLY DAN]

If the secondary pipes are glowing red they are hot enough. What is your draft? Seems to me the heat is good but not enough air is getting to the secondaries.

 

[warno]

If the secondary pipes are glowing red they are hot enough. What is your draft? Seems to me the heat is good but not enough air is getting to the secondaries.

I haven't tested my draft but with only 6 feet of actually chimney length I doubt is very much. I'm going to put a low cfm fan on the secondary intake and push some air through the tubes to test them out.

 

[STIHLY DAN]

That would explain it.