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Catalytic vs. Burn Tubes

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Rockey, Jan 21, 2009.

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  1. Rockey

    Rockey Minister of Fire

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    Is it just me or is my catalytic insert just much easier to operate and maintain good heat from? From what I have read it seems that most people prefer secondary burn tubes than catalytic. Here is what I my experiences have helped me learn about each:

    There is definitely a learning curve to using both correctly and maybe I'm still on the steep part of the curve with the Englander 30. Everytime I fill it up I think to myself how much longer that wood would have lasted in the catalytic insert upstairs and how much more effective heating it would have done. Granted this isn't a totally fair comparison because the Englander is in an unfinished basement with insulated walls, where a lot of heat losses are occuring, but I can extrapolate some useful information by watching the stove top temp. After I get the wood nice and charred (which happens fast in NC30) I close down my flue damper so it is closed and then I begin closing the primary air intake in increments. I usually stop when it is near the lip of the tray, sometimes further in sometimes further out. This will be good for about 400-450 stove top temp with the fan on high (add about 150 - 200 if the fan is off). Then I try to leave it alone. It stays there for about an hour and then the temps begin to drop and the flames start to die out. At that point I can let it slowly die out and the temps will drop to about 250-300 in a few hours and the wood will be mostly coals. If I open the air intake right when the temps begin to drop I can keep the temps up a bit more to a certain extent because the wood will then burn up faster and it will reach the coaling stage quicker. I have tried all different combinations of leaving the damper partially open with various settings on the air intake on the stove but the results are never like they are with the catalytic insert.

    My catalytic insert is so much easier (for me) to operate. I fill it, get it up to about 375 degrees and close the air intake all the way down and watch the temps climb to about 475-500 where it stays for hours even in the coaling stages. whne the coals are far enough burned down I repeat. This is all with about half the wood it takes to fill the NC30. I need to run both when it is in the teens or lower to maintain 70-75 in the house, so far I haven't needed the furnace and don't see any need for it so i am achieving that much. I am leaning towrads replacing the NC30 with a large catalytic that will hopefully be as easy to operate as my cat insert and give me a longer burn time. Does this seem unrealistic> Am I doing something wrong with my nc30?

    The NC 30 has about 30 ft of uninsulated ss flue plus the single wall pipe connected to the stove and two 30 deg elbows connected to it. That is why I added the flue damper. The insert and NC30 burn the same wood yet the flue from the NC30 almost always has white smoke coming from it, whereas the insert almost never does.

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  2. Wet1

    Wet1 Minister of Fire

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    I can't help you with your issues, but I'm quickly coming to the same conclusion regarding the advantages of having the cat. I had been toying with the idea of picking up a NC30 for my basement as I like the idea of having the large fire box, but after doing a lot of reading on cats, I think that's the direction for me. I want high capacity, long burn times, plus efficiency and going with a cat seems to be the only way to get this. I'm not crazy about having to replace the cat every 6 or 7 years, but that seems to be a fair trade-off for what is gained. Being able to reload the stove only once or twice a day is very appealing to me since I'm not always around to tend to the fire... and saving wood on top of that is icing on the cake.

    I hate to drop all this coin on a steel stove, but I think I'm going to buy the large BK for next season since it seems to be the only stove on the market which really meets my criteria. I wish there were other large cat options (hello Woodstock!), but it seems the BK is exactly what I'm looking for.
  3. karri0n

    karri0n New Member

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    Rockey,

    I've been making the same sort of observations. I have a secondary burn model, but I'm seeing more and more that catalytic models seem to get much better burn times and longer heat output. As someone who has owned both, I have a question for you. When the cat lights off the excess volatiles, does the heat from this ever reach the stovetop or make it into the house? I know secondary burn definitely raises the stovetop temp.


    Edit: wet1, I agree with you completely. The BK's performance seems great, but it really fails in the looks department, especially compared to the beautiful Cast Iron symmetry of my Isle Royale.
  4. semipro

    semipro Minister of Fire

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    Rockey, I have some of the same questions/concerns as you. I've been burning a Jotul Firelight Cat in the basement for 9 years (Oct - Mar) on the original catalytic converter and though the converter shows visible signs of deterioration its still hard to see anything but heat waves coming out of the top of the flue when this thiing is burning right. When I clean the flue I find it fairly unrewarding as very lilttle creosote forms even though I burn some very questionable wood. My experience with operation is basically the same as yours; get it hot, engage the cat, burn down about 3/4, reload, engage the cat. and so on.

    I still find myself tempted to make my next stove, likely an iinsert for the 1st floor family room, a non-catatlytic. I admit the challenge of working with a different technology is attractive to me. Howver, I've read some posts on some of the non-cat stoves that indicate that they have their own problems with operation and maintenance. In the mean time I'll keep monitoriing these forums and will likely be looking for some advice on which inserts to consider soon.
  5. Wet1

    Wet1 Minister of Fire

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    Valid concern. Since I want to stick it in my mostly finished basement, I'm not overly concerned about the appearance of the BK. OTOH, if I were looking for a stove to go in the living room, I would likely eliminate the BK from my short list. This is why I think there's a big opportunity for someone like Woodstock.

    The only thing keeping me from pulling the trigger on the BK today is the outrageous price (for what it is). I'm sure the performance is worth it, but I know there's a huge profit in this stove. I have someone else that wants one as well, so I'll probably see what kind of deal I can manage for two of them in the off-season.
  6. Rockey

    Rockey Minister of Fire

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    Karri0n -

    Yest the heat from the catalytic secondary burn definitley makes it way to the house. I believe it is because of the the design of the Energy King Insert that I have. If you look at the cutaway view here: http://www.energyking.com/woodstoves-cutaway.htm The hot air spends more time near the air box surrounding the insert and transfers well to house. The air is extremely hot exiting from the blower when the front of the insert reaches 500. I have yet to read about anyone else who owns a Bay 2000C Energy King insert but trust me, they are a very good high quality insert.
  7. savageactor7

    savageactor7 Minister of Fire

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    I fall asleep too quick if I'm in the stove room. That's why I chose a stove I could load and walk away from or fall asleep on.

    It's was my understanding with the cats you have tinker 15-20 min after every reload. I know that's no big deal for many cause they say with cats like the blaze king you load twice a day. I just don't want a stove that has to be monitored closely and that's my impression of cats.

    2ndly and more importantly I'm looking for heat, major heat, the kind of uncomfortable heat that you avert your eyes from, shed clothes, crave an ice tea/lemonade etc. Not that I require that heat mind you but certain people do and imo that heat comes for quantities of wood that I don't mind burning.

    I'm not looking for BS gimmick technology that's excels at smoldering wood for those pie in the sky 12 hour burns while saving the environment. Yeah that's important too I guess.

    Right now I'd rate our QF4300 as adequate but I'm looking to upgrade for something with more reserve firepower like the QF5700 or NC30 ...a big box stove...but I wouldn't rule out a big cat like a blaze king or PE if they were proven to me to be heat merchants.

    Edit ti add I meant to comment on how I like what I see here about the cats. performance.
  8. karri0n

    karri0n New Member

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    SA, my thing is that with a secondary burn model, once you are past a stage that you can get secondary burn, there's cool air rushing through the firebox and cooling the stove, as well as sending my heat up the flue. In a cat, it's still doing a secondary burn, just not a visible one, and the coals/wood in the box can still be heating, and I've seen reports of people reading 1500+ from the flue gases after the cat. A cat cranking away at 1500+ just HAS to be heating the house. I've seen lots of debate of cat vs. non-cat, and I can see the advantages of both, but the non-cats seem to only be at an advantage at the gasification stage. However, I can't speak from experience, and I've seen lots of seasoned wood burners that prefer non-cat, and lots that prefer cat. I gues it's really a matter of opinion, and what you're looking for from the stove.


    edit: I've also never seen anyone with a complaint about their woodstock, AND I've seen videos of woodstocks getting secondary burn in the firebox. The Woodstocks aren't big enough for my application, though.
  9. semipro

    semipro Minister of Fire

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    Wow, if stovepipe temps in some cat stoves are really that hot (and clean) it seems like some sort of heat exchanger right after the stove could really extract some more heat from the flue gases without causing other problems (creosote formation, poor drafting).
  10. savageactor7

    savageactor7 Minister of Fire

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    That has always been my first impression of cats as well. 1500 holy cow with 4 stoves we've never been there before. Sorry I'm such a doubting Thomas...I want to believe but so many worship at the alter of the long burns that we few that require heat at any wood cost are patronized with statistics.

    I think I can squeeze a few more degrees of heat by putting in an flue damper but the weather hasn't cooperated.
  11. karri0n

    karri0n New Member

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    Well, I also like the blinding heat production, but it's not useful to me when I can make 4 hours of blinding heat and 2 hours of coals burning off on the overnight burn, to wake up to a 120 degree stove on a 3.0 CF firebox. It's not like the cat stoves don't have an air control to turn the heat up if your burn time isn't as important. I still think even with this the cat will burn longer. I know if I'm getting the advertised 40 hours of burn time in a BKK, that it can't be releasing as much BTU/hr(Law of conservation of Energy and all), but I at least know that it's not just blowing air and heat up the flue.


    As far as those who worship the altar of long burns, it seems to me that a lot of the people on here at least are worshipping at the secondary burn altar, and believe that you will be throwing away your life savings by replacing your catalyst every 2 weeks.


    Once again, I can't speak from experience and I remain impartial, but it just sounds like the cat is the better option. I like a good light show too, but I must put function over form when it comes to keeping my family warm.
  12. Diabel

    Diabel Minister of Fire

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    I only have experience with two stoves: VC Encore 2190 cat & VC Encore non-cat. All I can say is that the cat stove uses 50% less wood during the same burn cycle with the same heat output. I have done this repeatedly over the past three years.
  13. karri0n

    karri0n New Member

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    That's an excellent experiment. Thanks for this post.
  14. Wet1

    Wet1 Minister of Fire

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    I would assume the 1500° temps seen are at the cat itself and not the gases further downstream (up the flue) after the cat. Regardless, much of this heat is transfered to the stove housing around the cat.
  15. Diabel

    Diabel Minister of Fire

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    That is also my understanding.
  16. Highbeam

    Highbeam Minister of Fire

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    We need options in cat stoves from name brand manunfacturers.

    The big blaze king requires an 8" flue and I recall the BK stoves being very expensive. The smaller BK Princess is a decent looking stove and uses a 6" flue but is only 2.8 CF. The BK line is actually growing on me, they are starting to look decent.

    I checked out the energy king and THAT is an ugly stove. (sorry for offending, personal taste)The insert looks better but still, not pretty. They also don't publish firebox volume or burn time. It takes a 21" log and uses a 6" flue.

    The woodstock is too small at 2.3 CF.

    VC is, well, a VC.

    I have a non-cat stove and it works fine but I don't need blinding heat as much as I need long burn times.
  17. bsruther

    bsruther Minister of Fire

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    Let me know if you decide to sell your Englander, I might be interested.
    I doubt that I live very far from you.
  18. savageactor7

    savageactor7 Minister of Fire

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    Good report Diabel ...I'm just assuming it's a lot colder up there too.

    Let me ask will the cat stove put out more heat than the other stove...can you feel its radiance from 15-20 feet away? I require blinding heat and since I'll be retiring next month it doesn't matter if I have to reload every 4hr or so.

    As far as a VC goes I'm not ruling them out either...they were THE premier stove maker for my entire life. Severe financial problems can make anyone desperate it's how they act from now on. But those VC's are imo complicated stoves that got me thinking I'm not cut out for a cat.

    Never the less nothing made in N America is ruled out and it's not like I'm gonna buy one next week.
  19. Diabel

    Diabel Minister of Fire

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    From 15-20 feet away you will not feel the radiance from neither stove, at least I don't feel it! At that distance the air is already mixed with room air/flow. As for the stoves...with the non-cat all of the reburn occurs at the back of the stove therefore in the first 3-4 hrs you feel only moderate heat at the front of the stove. With the cat stove you feel the heat at the front right from the start. At the coaling stage they're both the same.
  20. Todd

    Todd Minister of Fire

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    Rockey,
    Nice to see an Energy King burner here. I live about 2 miles from the manufacture. Small town quality driven company, never heard anything bad about them. I use to own a free stander but it was a non cat. I wonder why they switched back to cat stoves? Most manufactures are going away from cats which I always thought was a mistake. My dad pals around with the owner, I'll have to ask him about this. What size is the firebox on your insert? I looked into the insert years ago, but was too spendy at the time.

    I also have experience with both non cats and cats of similar size and can say without a doubt the cats seem more efficient and burn less wood, but both have their ups and downs.

    Rumor has it Woodstock is coming out with a large stove soon. I sent an email baiting them that question, we will see.
  21. begreen

    begreen Mooderator Staff Member

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    As Highbeam noted, there's a major difference in price between the Englander and BlazeKings. Englander used to make a cat model, the 24 ACD which sounded like a pretty nice stove. Too bad it was discontinued as it was alone it's field for price/performance. Also, there is a very significant design difference between the Encore cat and non-cat. Based on field reports here I could see how if the non-cat Encore was not set up with ideal draft, it might consume a lot more wood.

    That said, if PE decided to make a cat version of the T6/Summit I'd be interested. Burn times with softwood are not spectacular and I think it would flatten out the heat performance curve.
  22. TheFlame

    TheFlame New Member

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    The conclusion of Tom the Chimney Sweep (he's a member here) is that cat stoves do not excel overall compared to secondary burn stoves. He basically concludes that nobody should ever buy one (not his stated words, but it's pretty obvious from his comments).

    His arguments are found here:

    http://www.chimneysweeponline.com/hocats.htm

    I've been wanting to debate his arguments here for some time, and I figure now is as good a time as any.

    Discuss.
  23. begreen

    begreen Mooderator Staff Member

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    The article is a bit dated. True, improvements in stove design have produced non-cat stoves that burn almost or as clean as a cat stove. However, the few remaining cat stove mfgs. have ironed out most of the bugs and newer catalysts seem to stand up longer.

    A cat stove isn't for everyone, they do require some specific burning constraints and a little additional maintenance. But their real strength is turning out to be steady heat output which is not often touted as their best feature. This, together with long clean burns at low settings is enough to keep me interested. But the BlazeKing would never make it passed my wife into our livingroom and I'm unlikely to own a VC stove anytime soon.
  24. TheFlame

    TheFlame New Member

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    Dated? He totally poo-poos the esteemed Woodstock Fireview, known world-wide (or at least within the domain of hearth.com) as the gold standard for catalytic wood stoves!

    In any case, I love the part where "Todd", who owned both a Hearthstone Homestead and a Fireview, objectively states that the Fireview is a better stove and produces more heat with less wood. Then Tom goes on to state, "I'm not a big fan of some of the numbers manufacturer's toss around either, specifically heating area and burn time per load of fuel, which I feel are more than a trifle subjective and might get a bit exaggerated by overzealous marketing departments at times." After which he uses an entire page of numbers to refute Todd's claim that the Fireview is a better stove. Classic hypocrisy. I value the objective opinion of somebody who has burned both stoves over a bunch of calculated numbers as to why one is "better" than the other.

    While I don't want to beat up Tom too much unless he's present, when I stumbled on that page quite some time ago I always thought it was very slanted towards what Tom sells (non-catalytic stoves), and I always wanted to get the opinions of others on it.

    My esperience with my Oslo is that even though it is a really great heater, it reacts in exactly the way described in the original post. The heat output curve is very peaky, and I am fiddling with it alot. I still love it, but the catalytics actually seem like easier operation to me, it sounds like once you get the cat lit off you can do no wrong, whereas with a burn tube stove you could have the secondary burn stall if things aren't quite perfect, and then from there you got black glass and no heat.
  25. karri0n

    karri0n New Member

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    I read the articles on Tom's site, and I think I can see where the problem lies. The figures he uses for comparison(he relies on the nominal efficiency of the appliance a lot) are lab tests with ideal setups, in a warm lab with moderate outdoor temps. In the largely variable real world, with less than perfect wood, different temperature and draft conditions, I doubt there are man y situations where a secondary burn appliance is going to be gettin 100% perfect conditions for secondary combustion. The cats seem to be more versatile in that the cat isn't relying on draft for secondary combustion, and isn't constantly pulling extra air past the secondary burn stage of the wood burning process, thereby both cooling the firebox and burning the fuel at a higher rate than it would be if it was controlled by a single air inlet as in a cat stove.
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