Country Hearth / Us Stove 2000 secondary air intake

[barn burner]

FWIW I wanted to post this for some reference on this stove.

I loaded er up with small split black locust on a good bed of coals and things got a little bit too hot before I could ease it back down. Shut the Primary off and the secondaries kept raging and climbing. I took the ash pan out and was able to locate the secondary air intake. It's all the way to the back above the OAK and its about a 1/4" x 2 1/4" rectangle opening behind the primary. Stuffed it with foil until things got controllable again.

 

[StihlHead]

Interesting...

My Earth Stove overfires on occasion, usually after I start it and leave the damper open for too long or after opening the door and leaving the damper wide open (also by mistake). Generally the thing will start popping from metal expansion pretty fast, at which point I shut down the damper and turn a box fan next to it on high to blow off the heat. It usually settles down in a few minutes. The old stoves do not have the secondary air injection systems though, so closing the damper shuts the stove down pretty fast, no matter how hot it is.

From looking at the outside air supply intake and OAK on the US Stove user guides, it seems that it would be easy enough to put a baffle on the OAK and cut the secondary air supply off that way. Starving the air supply of the secondaries will stop them from overfiring in pretty short order. The EPA would not like that, as you will create a starved air situation that is typical in older model OWBs. But as a safety system, I think it would be good to have. I want to shut down any overfiring situations as fast as possible in a wood burning appliance. A few times our CB OWB damper was stuck open before I got a replacement damper and controller from the dealer and that thing shot 10 foot flames out the stack! They are pretty bullet proof though and if they boiler over (ours did twice before fixing the damper) the steam takes all the heat out of the system and they settle down pretty fast.

 

[barn burner]

If I had the OAK a baffle would work in theory. The only problem with that is it's not completely sealed where the OAK enters the ash pan area. There are air gaps all around the pedestal. I have since put in a pipe damper and that helps when things start to overfire.

 

[cptoneleg]

It amazes me all these overfires, what makes you think it was too hot, if I opened my ash door and pulled my drawer out during a full burn I am sure my stove would overfire, and opening the door would have been the reason. I load my stove with dry locust, I don't have any problems.

Always makes me think these stoves are sucking in air or something, If I had all these problems and safety issues I would have demanded my money back.

My wife runs the stove my grandkids not that hard.

 

[Huntindog1]

cptoneleg,

If you load the stove up really full with wood that burns really hot (Locust) , and if the coal bed is pretty thick and hot which loading on gets alot of the wood just not part of the wood going quickly plus being that there is not alot of open space left in the stove the stove will heat up pretty quick and get extra hot which in turns feeds on its self and gets even hotter. Add to this these stoves are smoke burners. They burn smoke more easily when they are hotter so that feeds the equation here. I also think when you load high up front in front of the window, what this causes is more restriction of the wood gases burning up under the baffle plate around the secondary burn tubes. When you load the stove full and up high close to the secondary burn tubes I think it creates like a small burn chamber, being a small area, heat is built up quickly from the burning smoke gases and its retained at a higher level. Then you stack the wood high up front and now that heat has to try and travel from up under the baffle plate to that open area up front in top to exit up the flue but now its blocked slightly from the high stacked wood up front of the stove, so this just adds to the heat building more and more.

One person on here also explained it like this, stuffing the stove full with little open space and when you get the heat up and your chimney has a strong draw your now sucking more air out of the secondary tubes since there is little open space, only space left is small area around the burn tubes maybe you can call that area a vacuum chamber.

 

[cptoneleg]

cptoneleg,

If you load the stove up really full with wood that burns really hot (Locust) , and if the coal bed is pretty thick and hot which loading on gets alot of the wood just not part of the wood going quickly plus being that there is not alot of open space left in the stove the stove will heat up pretty quick and get extra hot which in turns feeds on its self and gets even hotter. Add to this these stoves are smoke burners. They burn smoke more easily when they are hotter so that feeds the equation here. I also think when you load high up front in front of the window, what this causes is more restriction of the wood gases burning up under the baffle plate around the secondary burn tubes. When you load the stove full and up high close to the secondary burn tubes I think it creates like a small burn chamber, being a small area, heat is built up quickly from the burning smoke gases and its retained at a higher level. Then you stack the wood high up front and now that heat has to try and travel from up under the baffle plate to that open area up front in top to exit up the flue but now its blocked slightly from the high stacked wood up front of the stove, so this just adds to the heat building more and more.

One person on here also explained it like this, stuffing the stove full with little open space and when you get the heat up and your chimney has a strong draw your now sucking more air out of the secondary tubes since there is little open space, only space left is small area around the burn tubes maybe you can call that area a vacuum chamber.

I am sure if I tried real hard and do stupid stuff, I could do that I have alot of very dry Locust.

 

[cptoneleg]

cptoneleg,

If you load the stove up really full with wood that burns really hot (Locust) , and if the coal bed is pretty thick and hot which loading on gets alot of the wood just not part of the wood going quickly plus being that there is not alot of open space left in the stove the stove will heat up pretty quick and get extra hot which in turns feeds on its self and gets even hotter. Add to this these stoves are smoke burners. They burn smoke more easily when they are hotter so that feeds the equation here. I also think when you load high up front in front of the window, what this causes is more restriction of the wood gases burning up under the baffle plate around the secondary burn tubes. When you load the stove full and up high close to the secondary burn tubes I think it creates like a small burn chamber, being a small area, heat is built up quickly from the burning smoke gases and its retained at a higher level. Then you stack the wood high up front and now that heat has to try and travel from up under the baffle plate to that open area up front in top to exit up the flue but now its blocked slightly from the high stacked wood up front of the stove, so this just adds to the heat building more and more.

One person on here also explained it like this, stuffing the stove full with little open space and when you get the heat up and your chimney has a strong draw your now sucking more air out of the secondary tubes since there is little open space, only space left is small area around the burn tubes maybe you can call that area a vacuum chamber.

I am sure if I tried real hard and do stupid stuff, I could do that I have alot of very dry Locust.

Guess what I mean is my setup and chimney draft must be near perfect it operates exceptionally well, I load really good wood on hot bed of coals all the time, I did notice last night I loaded with Locust and watched it and the top piece up by the tubes fired off first before the ones layind on the coals, I let the rest catch and closed air nearly all the way down, all was good like I would think it is supposed to run.

 

[Huntindog1]

Have you ever used a moisture meter on your wood as it must be really dry to light at the top before the the ones down on the coals. I wish my wood lit off like that.

I seen on another one of your posts that your secondaries kick in at like 285 degrees, thats pretty good.

I have to wait till my stove pipe temp is about 400 to start shutting mine down. My wood test 20% and under after I split for the test. But it doesnt seem that dry as I get some stuff on the window and my starts are not all that good on hot coals. But when I do get it going it goes good.

 

[StihlHead]

Regarding overfiring: I have found that it is pretty easy to overfire any stove out there. OWB, new EPA, fireplace insert, or an old and creeky Franklin stove... too much air in any of them for any number of reasons and they will overfire on you. Subtle... yes. Over time Murphy's Law comes into play. You think something is idiot-proof, and then you load some wood into the stove, get distracted and wander off doing something else leaving an untightened door or the damper set open... and it overfires.

With our Central Boiler OWB, if the door was not sealed tight (door cord gets old and not sealing completely, door handle not adjusted right, or loose debris caught in there) it overfired. Also if the intake damper which controls the fire was not seating right from debris like a creosote chunk falling in there, or a loose setting (there are 3 adjustment settings on most of them), or being opened too much by a faulty controller or thermostat, they will likely overfire. In the case of those boilers though, the boil-over will take the energy away with the steam and that is it. It is a self resolving system.

In the case on any free-standing wood stove or fireplace insert, regardless of OAK or no OAK, any air leaks or open damper settings can lead to an overfire situation. In the case of my older Earth Stove here from the early 1980s, the door cord seal can fail just like in our Central Boiler; the cord gets old and compressed and winds up with air gaps over time. They need to be replaced regularly. Also the door levers and hinges come loose over time and use and they need to be inspected regularly and re-tightened. Leaving the damper set too high is another situation where they can overfire real easy. I find that burning different wood here with different outside temperatures requires a different damper setting on my Earth Stove. Its not a one setting burns all and heats the house the same. On colder days or with less dry or even different species of firewood, I need to open the damper more or less. Its an art, and it is a fine line. Some days the stove gets too hot in a few hours time, some days it gets too hot in a few minutes. Some days it does not get hot enough and I have to prod it some. I had a thin chunk of creosote fall off the chimney cap and partially clog up the stack a few weeks ago... that one threw me for a few hours.

Also in the case of all stoves that I have used, you can get what I call a bomb. Usually if the OWB was in shut down mode after firing real hot for a while, if I opened the door it would flare up and get really hot as the air hit the really hot wood gasses. That is common in starved-air systems, like in OWBs and older stoves with the damper closed way down. There are times when my stove seems tame enough and there is a good pile of coals and wood burning slowly in there, and if I open the door it will flare up and burn with a sudden high intensity. This can lead to rapid over-firing if you let it. Seemingly the newer secondary burn stoves reduce this as they inject air into the top level of the firebox which improves their efficiency. But when you put a lot of fresh air on a pile of hot coals and unburned wood that is ready to flare up, it will, regardless of the stove type.

 

[cptoneleg]

Have you ever used a moisture meter on your wood as it must be really dry to light at the top before the the ones down on the coals. I wish my wood lit off like that.

I seen on another one of your posts that your secondaries kick in at like 285 degrees, thats pretty good.

I have to wait till my stove pipe temp is about 400 to start shutting mine down. My wood test 20% and under after I split for the test. But it doesnt seem that dry as I get some stuff on the window and my starts are not all that good on hot coals. But when I do get it going it goes good.

That was B/Locust and its MC is 8%, I have been getting wood on an old Plantation that has lots of Locust that has been dead for a long time.