Barometric damper and slow burn on coal

[wiringlunatic]

Here come some more newbie questions that may have been answered years ago here before I knew where "here" was and may be stupid or show me to be so, but here goes anyway. For background, I installed a Kodiak wood/coal combo a few days ago. I had been planning to do this at some point carefully and slowly, but I guess God decided that now was the right time, as the heat exchanger blew on my forced air oil furnace and began to blow oil smoke out the vents. Thus began a frantic 8 hours or so to install this thing. That was Wednesday and we haven't frozen yet, but I do have some questions.
1. the pipe that I got with it has a barometric damper (I think that's what it's called -- that "T" with a swinging flapper on the side) I installed that as well as it was about 10PM and I didn't know if I needed it or not, but now I'm wondering if that isn't cutting my draft and making it harder to get good heat out of it. Just to note, I do have a standard manual damper on the pipe just below the barometric one. Also to note, the pipe had an adapter on it going from 8" to 10" pipe, so this was installed to a 10" chimney (or 10" pipe out the wall, it was back in the woods where no one would see it.) Will the stove run better if I remove it?
2. the previous owner's only real complaint about this stove was that it made too much heat. When I first fired it up on wood, it definitely burned fast. I found that the door gasket was the wrong one. I replaced that and we actually got it to burn through the night once or twice. Now we switched to coal and we can't seem to get much heat out of it. It burned for about 8 hours overnight last night with the air controls fully open (the ones on the door, the one on the ash drawer for wood were closed) and the manual damper only slightly cocked and probably only used 1/4 of the coal in it. Being easy on coal is one thing, but I want heat. How do I get this thing to crank? Could it have something to do with that barometric damper?
3. my wife says that the purpose of the manual damper on the pipe is only to "turn down" the fire. I thought I heard that once the fire was going closing the damper helped to hold more heat in the stove and thus the stove would actually put out more heat with the damper partly closed. Who's right? We're not fighting or anything, we're just not sure.

Thank you in advance for your help and God Bless

 

[Peter B.]

wiringlunatic wrote:

>It burned for about 8 hours overnight last night with the air controls
>fully open (the ones on the door, the one on the ash drawer for wood were
>closed) and the manual damper only slightly cocked and probably only used
>1/4 of the coal in it.

I know little about burning coal, and can't help with your barometric damper question, but one thing in your post stands out.

Coal needs underfire air to burn properly... which means the lower (ash drawer) control is the one that should be open... and the control(s) on the door closed.

Peter B.

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[wiringlunatic]

Someone else told me that since I posted, but changing the air didn't make it burn any hotter. It did stop bridging the coal though, so that's a big improvement. We put wood on top of the coal and opened everything to get it HOT and hoped that it would stay. The wood has been gone for some time now and it seems to be holding temperature. Is it possible that the chimney wasn't hot enough? It was drafting, no smoke came in the room even with the door open, but could it still not have been hot enough? I'm also still puzzled about the barometric damper.

 

[wiringlunatic]

Peter, one other thing. Is your busted Homelite as old as your Saab and your stove or is it one of those plastic things frome Wal-Mart with a Homelite label on it?

 

[Peter B.]

wiringlunatic:

Here in a nutshell is what I learned last season about burning coal...

-- Underfire air is necessary... other open drafts (except maybe on startup) only impede a coal fire.

-- A stronger draft (than typical with wood burning) is needed to 'pull' air through the burning coal bed. If the draft isn't adequate, the fire simply dies quietly. My understanding of barometric dampers is limited, but I believe they are mostly intended to even out or moderate an overdraft condition... meaning if your draft is (already) inadequate, the baro damper may actually be working against you.

-- Generally, but for a starter wood fire, coal is best burnt alone.

-- On a hot bed of coals, you should add a 'modest' quantity of coal, let that get burning strongly, then add another batch, let that get burning well, then add the main load of coal... as deep as your stove will safely allow.

-- A coal fire doesn't produce as much 'readily available' heat as wood, and responds much more slowly on reload or draft control changes... but once you've got a good, deep fire going (I've been told), the fire can easily last for 8-12 hours or even longer... depending on conditions.

-- Periodic shaking of ash is necessary... but proper shaking technique is the 'black art' of burning coal.

--

There are better informed coal burners (than I) here at Hearth.com, but you may also want to go here for 'compleat' information:

http://nepacrossroads.com/forum-55.html

--

My Homelite is also an XL Auto... but I don't know the year. It's an older one, though, with a die cast (?) or cast aluminum (?) body. I had a very odd problem with it where spark plug installed, it was *very* hard to crank (and wouldn't start). Spark plug out, the starter cord pulled free as you please. Never did figure it out, but I'll likely tear it down next year and have another go.

Peter B.

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[wiringlunatic]

Thanks for the info Peter. If your saw is an XL Auto, it is a 1965 according to the info on a site I found about old saws. The URL is www.acresinternet.com/cscc.nsf and is called the Chain Saw Collectors Corner. It gives detailed info on any saw you could imagine. It is actually capable of running up to a 24" bar and mine tears through wood like it's mad at it with a 16". I disagree with Homelite on the oil mix. It runs much cooler with 16:1 than the recommended 32:1. It is a die cast magnesium body. If I had to guess (and I'm a much better mechanic than coal stove operator) I would say that your issue boils down to either a restriction on air flow (either clogged muffler or stuck reed valves) or the carb is feeding to much fuel (the lovely elbow-dislocating jerk that you get from an overchoked engine) Get that saw running, you'll never buy a saw today with the torque that thing is capable of. I bought mine without the chain for $3 at a yard sale. When it fired on about the third pull at the sale after he said $3 I paid quickly and ran. It still fires easily and cuts like mad.

 

[Peter B.]

wiringlunatic:

I loosened the mounts for both muffler and carb on the Homelite, and still had the same problem.

A local friend suggested to me that (somehow) chain oil had leaked into the combustion chamber and created (effectively) a hydrostatic lock.

I'm a pack rat and won't let go of the saw... I'll get back to it next spring, summer or fall. I got mine used and reasonably priced (if I recall) too, and but for a carb rebuild, I never had another problem with it.

With everything 'right' and a sharp chain in place, I never imagined I'd want or need to trade it for another. I dropped back from a 20" bar to a 16" and was much happier with it.

--

And to all you Stihl owner's out there, you can at least *work* on a Homelite. The only Stihl I've tried to service was so cleverly ('Teutonically') put together that I just wanted to toss it out a window.

Peter B.

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[wiringlunatic]

Loosening the muffler may not be enough. They can build up carbon in the exhaust ports and loosening the muffler won't fix that. If you remove the muffler and check the ports you may find your problem. I can't conceive how bar oil could get into the combustion chamber, but if it did get enough in there for even a partial hydrolock the plug would be covered with it. It would probably take about a teaspoon to hydrolock that engine. That would make a royal mess of the plug. If the plug is covered with oil when you pull it, that's a possibility. If gas, then the carb may be overfeeding fuel. I don't think that's likely as that should have been stopped with the carb loosened. I seem to remember my late father who used to own the 770D that I now have telling me that the exhaust ports clogging was a common problem on those old saws. I haven't used it enough to clog them up yet.

--

And to all you Stihl owner’s out there, you can at least *work* on a Homelite. The only Stihl I’ve tried to service was so cleverly (’Teutonically’) put together that I just wanted to toss it out a window.

Peter B.

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I agree with you on those Stihls. They're fine for people who want a three pound saw that can not be serviced and whistles when it runs. For those of us who want a saw that growls and is heavy enough that it doesn't kick constantly and starts on the second pull instead of the second hour of pulling, it's old school Homelite all the way. Note on my post that I have an Echo as well. I've paid someone to fix it because I didn't want to take it apart and took it back to him when it still didn't work and it still doesn't have any guts. It's too light for a boat anchor... let's see... there must be some use for it.

 

[Peter B.]

wiringlunatic wrote:

>Loosening the muffler may not be enough.  They can build up carbon in the
>exhaust ports and loosening the muffler won’t fix that.  If you remove the
>muffler and check the ports you may find your problem.  I can’t conceive
>how bar oil could get into the combustion chamber, but if it did get
>enough in there for even a partial hydrolock the plug would be covered
>with it.

--

Good point about the oiled plug... I'm pretty sure it was dry. It's been quite a while since I even looked at the saw... but I'll get back to it... and take a closer look at the reeds and ports. I'm almost certain the exhaust ports were clear, but...

I'm a two-stroke guy from way back (Homelite, SAAB, Evinrude, VeloSolex) and (should) remember what can happen to mufflers, exhaust ports and such, but I have my lapses.

Thanks for the suggestions, and I hope you have more luck burning coal than I did.

Peter B.

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[crazy_dan]

It has been quite a while since I had burned coal. I burned coal in MT in an old Franklin stove had the bottom vents open all other vents closed. IIRC I even left the damper open fully. but I would get a wood fire going and get it to coal up real good then I would add some small coal like pea coal let that catch real good then add some bigger chunks of coal let that get going real good about 1/2 hour in between coal adding steps. then I would fill it up full of coal close the door and let ti go for 8-10 hours shake the ashes and add more coal if I still had a good coal bed I would just fill it up with coal and leave it alone for another 8-10 hours. When i was burning coal I had friends that worked at a good Anthracite(sp) mine and I could get a pickup load with side extenders level with the cab for $5.

 

[wiringlunatic]

I'm starting to get the hang of this, but it still doesn't seem to be getting as hot as I think that it should. I still don't know why there is a barometric damper on the pipe or if the draft is a problem with the lack of heat. I spoke to the son of the man who ran it for some 12 years. He said that they didn't install it but agreed that it may have been to limit the draft as the house was on a mountain and had a lot of wind making a lot of draft. I've learned that when the stove dies down (like overnight) I have to put some wood in it to get it up to temp or it will keep "idling" -- it will keep burning, but never get very hot. If I warm it up it burns better, I assume that this is due to an increased draft (I can see the flames and smoke being pulled back harder as it heats up). I had almost resigned myself to the fact that I may have to line the chimney with stainless steel when I remembered that the natural gas water heater vents into the same chimney about a foot higher than the stove (before you lecture me, yes, I know that it is not up to code to share a chimney between gas and solid fuel. I have a direct vent tankless water heater on order which should be here in the next few days. The water heater will then be off the chimney and the hole sealed.) The chimney was borderline on draft tests for the oil burner that was on it prior to the stove, hopefully that was just due to the 3" hole that is from the water heater. Help me out -- am I correct in saying that the water heater vent may be a major draft leak? Is the baro damper a draft leak or a help? I've been told that coal can give troubles on a windy day, but on a recent windy day we had no problem whatsoever. Could that be due to the baro damper or is that just the chimney construction and landscape? Or was that a characteristic of old unsealed stoves only? Sorry for all of the questions, but were it not for our kerosene heater and some small electric heaters, things would be rather chilly around here.

 

[wiringlunatic]

I think I found one more piece of the puzzle. The coal I got (free for the hauling) is a random mixture of all sizes, from dust to the size of my fist. I tried just putting in the chestnut sized coal and it seems to burn much hotter. My theory is that more air can pass through the coal bed, thus burning hotter. I'm not sure if I'm right or not. Also, when it cools down some, I still need to burn a little wood to get the draft going good again if I want full heat. Hopefully the new water heater will be here in the next few days and then maybe the draft will be better without the 3" leak in the chimney a foot above my flue pipe. I'm still puzzled as to the baro damper. Does anyone out there know about this? Is this hurting, helping, or doing nothing for the draft?

 

[LeonMSPT]

A leak in the chimney from an unplugged appliance thimble is decreasing the draft... sounds like a draft issue, as the draft is what makes a solid fuel heater "go".

The barometric damper is likely needed, but should be adjusted properly using a manometer, when you've got a hot fire going. It will open when the fire gets hot and the chimney starts pulling harder, or if the wind blows and pulls a stronger vacuum on the chimney. Most coal burners, go over the NEPA and check it out, say it's a must have.

I've got an open clean out door, until I can redo the chimney connector job and install the barometric damper on my new wood/coal boiler.

 

[LeonMSPT]

Pull a draft up through a coal fire... it gets hotter and hotter... problems with overdrafting is too much heat. You're not having that trouble, but plugging the hole in the chimney will change that equation...