Harman FireDome Tricks

[stonewall123]

Hello All, I have been lurking for sometime but thought I would join the club.

My setup is a Harman Oakwood with a 28 foot evil outside masonry chimney with an 8x8 clay liner. I vent the Oakwood out the top and through one 90 degree bend to the thimble. (Another 90 degree turn to head up the flue) I thought I'd share a couple of tricks I've come up with to keep the Harman stove humming along.

I used to get a smoke smell in the house when I had a full load (reload) in the stove and the afterburner was going. Drove me nuts. It never set off the smoke alarms but it would wake me up at night. Anyway, now when I go to reload the stove, I take a small split of poplar or pine (fast burning) and toss it in with the air controls wide open and the bypass damper open. I let it burn until my thermometer (placed on the lower right corner of the flue collar) is between 500-600. Then I add the full load, wait till it catches (steady flames) and close the bypass damper. Smoke smell gone.

My theory is that near the end of the burn cycle, the flue gasses just aren't hot enough to pull all of the smoke out through the afterburner. Burning that small split seems to "charge" the flue and the combustion pack.

Another tip is to use two thermometers. I have the one previously mentioned and I also place one on the side of the rear housing about half way up. This way I can monitor how the afterburner is doing without walking in and out of the house.

Finally, keep a thick hot coal bed and the difference is amazing.

I admit these stoves take a bit of learning but I really do love the long burn times and the even heat. It really throws the heat! I hope these tips help some fellow Harman owners.

 

[Backwoods Savage]

Welcome to the forum BackwoodsBarrister.

That certainly is an interesting way to reload a stove but I'm not sure I'd recommend it. As for me, I'm not about to open the firebox door with the temperature that high. I like my eyebrows as they are. What you are really stating is that is pays to get the flue good and hot on reloads to make sure the smoke all goes up rather than in the house. That is indeed necessary and that is also the reason the stove is burned with full open draft for a time before opening the firebox door for the reload.

Perhaps you are having a harder time getting the reloads to start burning good because your wood is not quite as dry as it could be. It should either be poor draft or not quite as dry of wood as it could be and we usually find it is the wood. Your chimney surely should be high enough at 28' so I would naturally look at the fuel. That does not mean you can't burn it, but it could be a big part of the problem. Keep in touch to let us know how it continues as the weather chills.

Good luck.

 

[branchburner]

Hello, fellow Oakwood owner! Not too many of us around here. Glad you are having good luck with the stove, not all do. I must say, in the dead of winter it puts out some serious heat, as you note. The phrase "humming along" is exactly how the local dealer desribed the stobve when it is cruising.

I like the idea of two thermometers. I'm getting a pretty good feel for when the AB is going just from the visual differences in the firebox. I would say my stove is a pretty good moisture meter, too. It lets me know real quick when I try to slide by with a marginal split on low air.

Do you have the grill?

 

[stonewall123]

Branchburner, I do have a grill, although I haven't tried it yet. The problem is timing the bed of coals when I am hungry! I do have some apple wood stowed away for when the time is right though.

Backwoods Savage, I think you may be right. Last year my wood was not up to par, this year it has been sitting in the sun covered for a long time and has that baseball bat sound when I hit two pieces together. So maybe I thought I figured out a trick that really was just the improved quality of the wood.

Just to clarify though, I only put in a split about the size of of the fat end of a baseball bat. Really, you could consider it a large piece of kindling. While the thermometer is reading high, the overall firebox is not nearly that hot. I think it is just the hottest spot on the stove when the bypass damper is open, so that's why I put my thermometer there.

 

[stonewall123]

Branch, I'm surprised to hear that some don't have good luck with the stove. I love mine. Of course, I switched from a non-EPA Appalachian Stove insert, so really any new stove would be an upgrade from that. The million dollar question is how long the combustion package lasts. When my chimney sweep came out this spring, he did a visual of the combustion package and it still looked new. He said "keep doing what you're doing."

 

[branchburner]

I think if the stove is not overfired the CP should last many years. It may need to be cleaned after a few years, because I don't see any way that some fly ash isn't going to eventually build up back there.

I think most others with problems have either too much or too little draft, but some also have a hard time perfecting their own technique for a good burn.

 

[jdonna]

I will chime in as well on this one. I used to use a non contact digital thermometer to monitor stove performance.

The stove top thermometer is great for monitoring the first burn to get a charcoal base but is not accurate when you are in secondary burn mode. I have a thermometer placed on the side of the stove near the bypass handle. The smoke exits the combustion package there if you have ever had one apart. The majority of the heat is on the rear sides of the stove.

You will be quite shocked at the temperatures you will be reading there.

I have a thermometer also 18" up on the flue pipe, non-contact probe style.

I have heard some people placing less seasoned wood on top of a load of seasoned wood as well to slow the burn and get a little bit more controlled heat out of it.

Anyone else having smoke odors as well with their stove? I have often wondered with that shoe brick has a gasket underneath it and a direct source of combustion air.

Secondly with gasket issues with these right out the box, one has to wonder with the rear cover and side panels ,the integrity of the gaskets.

I had a small casting hole in mine, the rear firedome casting cover, which has some stove cement on it temporarily.

 

[stonewall123]

Jdonna,

I have tried placing less seasoned wood on top of the load when things are going strong. No negative effects that I can see. Although, no real positive ones either. I'd call the dealer on the hole in your casting cover, that should be replaced under warranty in a snap.

I hear what you are saying about the gaskets. I still think that there is sometimes an "overpressure" issue when running a full load without the flue being hot and it just pressures the smoke out through the gaskets. The trouble is that it is hard to sniff it out when the stove is going strong!

I agree with you about the thermometer on the side. Mid 700's are common. What are your stack temperatures reading on your probe thermometer when you are in afterburner mode?

Also, where are you Oakwood burners setting your air control once you get the afterburner going? I usually sit between 3-6 notches, rarely above 8.

 

[branchburner]

Also, where are you Oakwood burners setting your air control once you get the afterburner going? I usually sit between 3-6 notches, rarely above 8.

I usually start the AB with half-open air, at 8, then step it down to 6, 4, and finally 2 or even 1 for overnights (depending on the wood and how cold it is). I used to shut it all the way, but only do that now when it's in coaling stages.

 

[branchburner]

Both of you fellows mentioned a smoke smell. How old are your stoves, and have you ever pulled the AB to clean the ash?

 

[stonewall123]

Mine is just going into its second year. I have the installing dealer come out and service the stove and sweep the chimney each year. He did the ash vac from the top and inside, did not remove it though. All signs point to good AB performance, not smoke at chimney, etc.

 

[jdonna]

I hear you there, I would not go off of my numbers or advice. I have had a really bad experience/ multiple issues with my stove since day one. I bought mine two years ago.

Good luck with the warranty issue if you ever have one. still in limbo, I'd write an novel on my Harman experience, but will do so another time.

The prob temps really depend on the stage of the burn, had it well over 1200 degrees and when I get to behave I can see 600-800 on small loads.

I have yet to figure out that faint smoke smell when burning as well, When I did run my stove the smell seems to come on more strong when you have a faint flame dancing and rolling on the fire box.

I had to run mine on two notches or so or it would go nuclear even with the key damper turned half way on my chimney pipe.

What kind of burn times are you seeing with your stove, what do you burn?

I burn white and red elm along with oak.

Keep up on keeping your secondary combustor clean.

Jdonna,

I have tried placing less seasoned wood on top of the load when things are going strong. No negative effects that I can see. Although, no real positive ones either. I'd call the dealer on the hole in your casting cover, that should be replaced under warranty in a snap.

I hear what you are saying about the gaskets. I still think that there is sometimes an "overpressure" issue when running a full load without the flue being hot and it just pressures the smoke out through the gaskets. The trouble is that it is hard to sniff it out when the stove is going strong!

I agree with you about the thermometer on the side. Mid 700's are common. What are your stack temperatures reading on your probe thermometer when you are in afterburner mode?

Also, where are you Oakwood burners setting your air control once you get the afterburner going? I usually sit between 3-6 notches, rarely above 8.

 

[branchburner]

What kind of burn times are you seeing with your stove, what do you burn?

I burn white and red elm along with oak.

The burn times vary greatly with weather conditions and wood dryness/size. Big oak splits can give me ten hours tops, but usually I'm getting 6-8 hours. At times the stove can gobble up smaller, very dry splits, even with the air set low. But other times they will cook along nice and slow. It seems like the middle stage of the burn often occurs more quickly than it should.

More than other stoves I've used, burn times seem to be greatly controlled by how hard the natural draft pulls the (uncontrolled) secondary air. I have a 6" insulated 22' liner, interior chimney, that pulls hard.

I'm burning pine in the mix, along with cherry/maple/birch/poplar/ash, during spring and fall. Saving the oak, except the older, long-dead stuff, which I have lots of. How long cut/split/stacked is your wood?

 

[Troutchaser]

I sometimes had a slight smoke smell when those flames danced around in the stove. I think it was something of an explosion that forced air out into the room. I don't let that happen anymore. If it does, I've lost draft.
Do you guys keep flames inside of the box when in afterburn? Or is the box just dark with an orange glow at the CP? Dependent on coal bed?
If I turn the air down too much, it seems that I can lose the afterburn towards the tail end of the cycle and get a llittle smoke.
I definitely need 800+ flue temp (probe) to get things started. My only runaway started about an hour into the cycle with a fully loaded stove. I had a leaky door gasket at the time. I also had med. to small splits stacked one on top the other and they seemed to all combust at the same time- not adequately seasoned. Just follow posts from the tubers and you'll see that downdrafting isn't the only way to go nuclear.

I say this because our stoves are very similar and I try to follow posts with other similar stove owners.

 

[branchburner]

Do you guys keep flames inside of the box when in afterburn? Or is the box just dark with an orange glow at the CP? Dependent on coal bed?

Yes, if I have a deep coal bed and the thing is cranking out the heat, I'll shut the primary right down so there is just the glow, or a few wisps of flame in the back. From a cold start, if I don't keep flames for the first hour or two, it's likely to stall out.

I heard the Leyden has no solid fireback to protect the fragile CP back there - is that true?

 

[Troutchaser]

No protection of the CP. Brick over the top of it. I took it out over the spring for a cleaning and to get some idea of what was going on back there. I have a small chip off of one corner, but looks fine otherwise. I am careful with the poker and wood not to bang it.
that is the experience I've had with the afterburn. Takes a good-scratch that---GREAT--- coal bed to close the primary. If I don't have it and I shut the air completely down, the flue temps. plummet inside of five minutes.

I'd be curious to know if you're cold starting everyday like me. I'm trying to get a feel for operating the stove over the course of the evening without it consuming too much time burning down to coals and then closing bypass, etc.
I'm thinking big chunks and hunks of wood are best for this stove in downdraft.

 

[branchburner]

I think this style of stove is best suited to 24/7 deep winter burning. Cold-starting is kind of a pain - and since the family doesn't mind, I tend to overheat the house so I can get by with fewer but longer fires. The best thing I did this fall was add firebrick, so I am burning shorter wood in a smaller firebox and getting better secondary combustion with small but long fires. I also keep the ashpan full so the hot coals don't drop down. Working good!

 

[stonewall123]

I get consistent 10 hour burns (stove still 250 or higher and hot coals that light wood immediately) I burn poplar in the shoulder seasons, locust, oak, beech and apple in the cold. I agree with BranchBurner, this is a stove that is made for the dead of winter. Occasionally, I will do a small split fire just to heat the stove up to take the chill off but most of the time, if it is not below 45 degrees, I use my furnace. I am not ready to swear off using a downdraft stove yet, everything design has a tradeoff. Branch, I will try leaving the ashpan full to see if that helps.

Like folks have said a good coal bed is necessary. I usually have small flames at the shoe brick and occasional "northern light" flames when things are going good. Getting the flue nice and hot between reloads has fixed the smoke problem for me.

 

[branchburner]

I usually have small flames at the shoe brick and occasional "northern light" flames when things are going good.

It's not the flashiest light show, but it can be very soothing and hypnotizing. Especially if you get one of those wispy, bluish flames dancing in thin air.

 

[Troutchaser]

I leave my ashpan full because others have said that it helps. I find it a pain to empty anyway.
Agreed. Those syrupy blue flames are tops. You're in the zone if you can sustain that.
Barrister, I'm hoping for a ten hour burn sometime soon.

If in a hurry, I'll go from kindling and small splits to mediums to downdraft all in one motion, letting the coal bed form while I'm heating the combuster after the stove and flue get hot. Since I usually have to keep the primary open for a good while anyway after closing the bypass, seems like a sensible idea. I can do this and still get little smoke at start-up if things are hot.

Bburner, you asked about CP protection. Techinically, the shoe is at the back of the stove and the combuster is behind that. Not sure if that is what you were asking.

 

[branchburner]

Bburner, you asked about CP protection. Techinically, the shoe is at the back of the stove and the combuster is behind that. Not sure if that is what you were asking.

Yes, combuster is behind the shoe - just wondering what other protection the combustor had. I can toss logs and poke the back of my firebox without any worries, there is metal and solid refractory back there. I had heard the Leyden offered less protection, and it was very easy to damage the fragile part with logs/pokers/vacuums. etc. Is that true?

 

[Troutchaser]

I can see me damaging the shoe with the poker one of these days, but the combuster back there shouldn't be in trouble. There is a piece of metal holding in the brick above the shoe, but nothing else. I damaged the impossible gasket that sits between the shoe and the brick over it and I can see secondary air leaking through there now. Not much, but noticeable in a hot fire.

The shoe is also split into two halves. Depending on wood arrangement in stove, 1 side of the shoe opening will be glowing while the other side remains dark. Sometimes half the load will glow the left side, then the latter part of the burn will light off the right side. Maybe somebody at Travis was thinking ahead on that.

The OP mentioned reloading by dropping in a split to charge the flue. I usually just throw small splits on hot coals, let it cook 1/2 hour or so, and then load with medium and large splits before closing bypass.
What do you do?

I loaded at 9 last night and had a nice pile of glowing coals at 7 this morning. Stove temp. 100*. Guess stove companies would call that a ten hour burn.

 

[branchburner]

The shoe is also split into two halves.

I usually just throw small splits on hot coals, let it cook 1/2 hour or so, and then load with medium and large splits before closing bypass. What do you do?

My shoe also split into two, which I put back together with stove cement.

On a hot reload, I usually throw the larger splits right along with small splits on the coals, then step down the air from full to 1/2 to 1/4, over 5-15 minutes, before closing bypass. Then again step down the air, from 1/2 to 1/4, over 5-15 minutes. If I waited a half hour with small splits on a deep coal bed with bypass open, the wood would be gone (and the stove might be, too!). My stove drafts very hard when it's hot.

 

[jdonna]

Here is a shot from the oakwood on a half load of decent sized seasoned splits an hour into the burn, when I was running the stove. The thermometer is placed near the bypass damper. No wind and a 37 degree outside temp. That is what makes a guy spill coffee on his lap from your hand shaking.

3-4 inch coal bed with four lines of primary air, key damper turned 1/3 of the way.

I always wanted kids, wound up with a Harman that I had to baby sit.

 

[jdonna]

Inside shot of firebox.