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Letters: Catalytic vs Non-Catalytic Woodstoves

Q: Am wondering if you'd care to share your opinion about the Vermont Castings "Defiant Catalytic" woodstove. We had to replace the catalytic converter two years after installation, and now must replace several burned-out internal parts not covered by the warranty. We've also had trouble since day one controlling the fire. We were told this stove is cutting edge technology, and really like how the cast iron looks with the porcelain finish, but frankly, we don't like the catalytic converter. We notice the woodstoves on your web pages are all noncatalytic. Doesn't the EPA require catalytic converters now?

Sweepy A: EPA regulations limit the amount of particulate matter, measured in grams per hour, that may be emitted by a woodstove; they don't tell the manufacturers which method to use to achieve this level. Incorporating a catalytic converter is only one way to clean up woodstove exhaust, and it is far from the most popular.

The story of the catalytic woodstove begins over two decades ago, when only a handful of states had as yet passed woodstove emissions regulations. At that time, manufacturers who wanted to sell woodstoves in regulated states found that simply incorporating catalytic afterburners into existing models was a relatively inexpensive way to clean up the exhaust. (Your "Defiant Catalytic", for example, is basically the same stove as VC's old Defiant model, but with a catalytic converter added). This "bandaid" approach produced several models which, while clean-burning enough to sell in regulated states, didn't turn out to perform as reliably in the field as the high-emissions models the woodstove manufacturers continued to sell in the much larger, unregulated marketplace.

Back in the '80s, we sold a few catalytic woodstoves, but dropped them almost immediately because of negative customer feedback (the need to "babysit" the stove until it came up to catalytic ignition temperature before activating the converter, lack of control of the fire, the frequent need to service or replace the expensive converter element, etc.). By and large, these complaints remained unresolved by the manufacturers, presumably because (1) solutions didn't readily present themselves, and (2) the numbers of catalytic stoves sold at that time were relatively small. When the EPA stepped in and announced their intention to outlaw high-emissions models in ALL states, many manufacturers (Vermont Castings among them) were left with only their "bandaid" catalytic models to sell; suddenly, catalytic-equipped woodstoves were being sold in large numbers all over the country, and consumer complaints multiplied proportionately.

One by one, US manufacturers grew tired of the customer dissatisfaction, expensive warranty repairs and poor performance associated with their catalytic models, and began to reject the trouble-prone catalytic technology in favor of an alternative, non-catalytic, clean burning technology that had been developed in New Zealand, where woodstove emissions had already been a hot topic for over fifteen years. With some minor design improvements, this technology was adapted to comply with the stricter US standards, and was easily applied to woodstoves of plate steel construction, where only a few changes in the assembly line were needed to convert from catalytic technology to the non-catalytic secondary burn designs.

Not so with cast iron stoves like your Defiant. While manufacturers of plate steel woodstoves could weld up a prototype in a few hours, then test, modify, reweld, and retest it as needed until it met the EPA standards, cast iron stove manufacturers would be faced with a tedious and expensive process involving much design engineering and foundry work, as all preliminary parts would have to be cast in custom-made molds, one at a time, prior to assembly and testing. Thus, manufacturers of cast iron stoves tended to lag behind the rest of the industry in adapting their models to the new non-catalytic technology. Meanwhile, the basic New Zealand non-catalytic design underwent further refinements, and other secondary burn designs were developed, until non-catalytic technology became the standard in the US marketplace.

Vermont Castings has for some years now been actively engaged in the process of adding non-catalytic models to their product lineup one by one, starting with their smaller models (the non-catalytic design is easier to implement in smaller stoves). Today, they offer 18 non-catalytic models and only 6 catalytic models.

In the meantime, catalytic technology has also continued to improve. Repositioning of the converter relative to the flame path addresses the flame impingement problem, which had previously shortened the lifespans of the converters in earlier designs. Changes in both the substrate and the catalyst itself have resulted in longer lifespans and more consistent performance. Re-designed access openings and holding brackets have made cleaning and replacement the element less of a chore. Consumer education has perhaps been the biggest factor: today's catalytic stove owners seem better informed about what not to burn, and are generally more knowledgable about care and maintenance of the converter itself (like keeping it clean, and replacing it when needed).

You asked for our opinion, so here you go: if the problems you describe have become more than a nuisance, the best solution we can come up with would be to trade your Defiant in on a non-catalytic stove. All new woodstoves sold in this country must be EPA approved, so any stove you buy will be a low-emissions design, whether it has a catalytic converter or not. We've sold non-catalytic woodstoves for over 20 years now, and in our experience, non-catalytic technology has proven itself effective, reliable, and easy to operate. Since you mention above that you really like the looks of your Defiant, you might consider Vermont Castings' newest version of the Defiant, which is, as you might have guessed, non-catalytic.

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Letter #2: Disgusted with catalytic stove

Q: I found your explanation of wood stove experiences to be informative and goes along with my experience. I should have checked the web before I bought a Harman catalytic wood burning stove. It is a poor stove and I am disgusted with it. Do you have suppliers in PA for your non catalytic stoves?

Sweepy A: The main reason we published our website was to make our favorite products available in areas that don't have dealer representation. If you've called around to your local stove shops and can't find the products we offer, we're your backup option. We ship direct to our internet customers, via motor freight, liftgate delivery. If you'll E back your address, we'll be happy to get you a delivery quote: chances are, your freight charges will be about the same as the sales tax you'd have to pay if you did have a local dealer!

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Letter #3: A satisfied catalytic owner who happens to have the same exact stove letter #1 is complaining about.

Q: This letter is prompted by your comment that you've received zero e-mails or letters in support of catalytic-operating stoves. After reading about the ineffectiveness of so many catalytic combuster stoves on your web page, and how much mail you've received after you published this opinion which also expresses disgust with these stoves, I feel I must report that I have had a different experience.

We have a Vermont Castings stove w/ a catalytic combuster. It operates wonderfully. We heat a 2200 sq/ ft. house fully w/ it, and w/ its firebox filled (we have their largest model, at least as of 9 yrs. ago), and with the combuster engaged, the fire lasts throughout the night, w/ temperatures in the teens outside. Our forced air heat system's thermostat, returning to 68 degrees at 7 am usually needn't even kick in at all. Also, now in our ninth winter w/ this stove, we've replaced the catalytic combuster only once.

Apparently, this experience depends on the stove and manufacturer. I expect one catalytic stove is not the same as all others. Beware of overgeneralizations.

Sincerely,
Eric Mendelson
Ithaca, NY

SweepyA: Hi Eric,

For whatever reason, yours is indeed the first letter we've received in defense of a catalytic woodstove, and, ironically enough, the stove you're writing to praise is the exact same make and model the writer of letter #1 above was complaining about. I'm glad you're happy with yours, but there are a few factors you don't mention:

First, your positive experience with the performance of your stove is consistent with the experience of our customers and service clients who have chosen non-catalytic stoves in the past two decades. They're as happy with their non-cats as you are with your cat.

Second, your 9-year-old Defiant Catalytic is a different stove than the same-name model currently being marketed by the new owners of Vermont Castings. Several design changes and material compromises have taken place in the ensuing years, including a reduction of the lifetime warranty to just 3 years.

Third, you don't mention the initial purchase price of catalytic stoves. If you bought your Defiant nine years ago, you paid over $250 more for your catalytic stove than you'd have paid for the comparable non-catalytic models we sold back then. Even today, if you were shopping for a cast iron all-night burner that produces 50,000 btu/hr, you could choose between the still-catalytic version of the Defiant and the non-catalytic Hearthstone Shelburne, for example, which retails for several hundred dollars less and carries a lifetime warranty. You would also have to pony up for the more expensive 8" connector pipe and chimney the Defiant requires for installation.

Finally, you don't mention the on-going operation expense associated with catalytic stoves. You have already replaced your converter element once, at the expense of at least $100.00 - $200.00, plus the value of your time spent (or the service charge from your dealer) to install the new unit. At nine years of age, your stove is about due for another converter replacement (and the concurrent expense).

The bottom line is, after ten years or so of satisfactory operation you will have paid an extra $800.00 or more to heat your home with your catalytic stove as compared to the equally satisfied owners of similar clean-burning but non-catalytic models.

Letter #3A: Eric again, still satisfied

Q: Good points and a good argument, & thanks for writing back. Please recognize--and perhaps I was unclear in my hastily written letter--I'm NOT arguing that catalytics are automatically better, but that they as a whole class are not inferior or bad, w/ all owners having terrible experiences, as your web article certainly suggests. I know others here who swear by their catalytic stoves.

Your argument that there is added hardware expense w/ catalytics is a good and reasonable one. However, I don't think you're considering the wood savings. I believe that I burn less wood w/ the re-burn of my catalytic combuster than I would use otherwise, and in our cold winter environment, that can add up. I can't offer you research data or any specific monetary numbers, but I know I burn less wood--in our larger house--than our neighbors who use their stove similar amounts. We have a yearly savings there. Whether this compensates for the added front end cost of our stove or for the replacement combuster elements every 5 yrs. or so, I can't say. I do know that it isn't simply the $500 difference you argue. Your careful financial argument is ignoring the amounts of wood needed. More to the point, the implication that nobody prefers catalytics, as your article suggests in saying that nobody's written you w/ anything good to say about them, is false.

Thanks,
Eric Mendelson

SweepyA: Hello Again Eric,

I'm not trying to bum you out here, but your fuel savings argument based on your observations of your neighbor's fuel consumption doesn't hold water. The fact is, there is much laboratory evidence to the contrary. Woodstove efficiency testing reveals the exact amount of heat a given stove delivers for a given quantity of wood burned, and independent laboratory test results document that EPA approved non-catalytic woodstoves are just as fuel efficient as catalytics. This means catalytic stoves won't burn any less wood than non-cats to heat the same area.

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Letter #4: Yet another Defiant Catalytic owner!

Last year, 2003, I bought a Vermont Castings Defiant wood stove with a catalytic combustor. I wanted to replace a smaller twenty year old Reginald 100. Because these are two very different stoves, I've got some questions.

Problem one. Draft. I have a 7x 7 id flue liner inside a brick masonry chimney which is inside a two story house. I had to buy a reducer from the manufacturer to take an eight inch oval stove collar to a six inch elbow that inserts into a six inch thimble in the chimney. The draft was fine with the Reginald's 6 inch collar, but I seem to be lacking a good draft with the new stove. The new stove is a top loader and sometimes smoke spills out when I reload. Is my flue liner too small? If so, is my only solution to get a smaller stove?

Problem two. Baby-sitting. When I first start a fire, before engaging the combustor, I spend more time then I like getting the stove up to 450 degrees--the recommended temperature for closing the damper in the stove. However, once the combustor is working, the stove burns nicely. If I removed the catalytic combuster, would the stove burn any differently?

If you have any tips that can help, please let me know.

Yours in wood heat,
Steve Turnage
Hague, Virginia

Sweepy Hi Steve,

We get numerous complaints about top-loaders smoking into the room when the top is open, and this is bound to happen occasionally, as no chimney system can ensure perfect draft conditions all the time. That said, your 7 x 7 flue is not too small at 49" cross-sectional area, but your 6" connector pipe at 28" CSA might be causing some restriction. See if your dealer can supply you with an 8" oval to 8" round adapter, then enlarge your thimble opening and try using 8" (50" CSA) connector pipe. This might cut down on the number of back-smoking incidents, but again, that occasional experience seems to be unavoidable with top-loaders.

Here's a technique you might try: instead of pulling the top open all at once when you want to tend your fire, just crack it about an inch first while you slowly count to five. Then, open it the rest of the way slowly, to avoid vacuuming smoke into the room.

Your complaint about waiting so long to get your stove up to catalytic lightoff temperature is also one we hear quite often about catalytic stoves in general and your stove in particular, but it is a drawback you must learn to live with: if you remove your catalytic converter, you'll instantly increase your particulate emissions output by about 60 times and increase creosote formation in the flue by about 10 times, while cutting your heat production roughly in half. Not a good idea.

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Letter #5: Tired of waiting for lightoff, can't wait to switch!

I built a house about 15 years ago and put in a [non-catalytic] Kent. I will not waste time praising this stove but only say I sure wish I had not sold it with the house.

I have lived with and used many other stoves since then (not by choice). My recent nightmare is a catalytic Englander. I just cannot wait until I can afford to replace this monster. An hour to light the stupid thing? I am surprised I don’t have to sing it a little song as well. If I could find some sucker who likes the catalytic technology to sell this thing to I would dump it before breakfast.

Xavier

Sweepy Hi Xavier,

Swapping out woodstoves is hard work. You might want to wait until after breakfast.

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Letter #6: Prefers new Cat to old Non-Cat

I like your library section, lots of good info. One thing kind of troubles me tho. When I saw the section on why you sell non cat stoves vs cat stoves, I thought I should give you another positive review on cats.

I recently purchased a Woodstock Fireview to replace a Hearthstone Homestead. In fair and honest comparison I have to say the Fireview is a far better stove. If it wasn't I could of shipped it back for a full refund and kept the Homestead.

The Fireview does burn less wood and give more heat than the Homestead and I think its because the cat is designed to burn slow and feed off the smoke. A non cat has to be burned at higher temps to keep that firebox over 1100 degrees to maintain secondary burn. I noticed quite a difference in stove pipe temps between the two stoves. So from experience I would say a noncat loses more heat up the chimney than a cat.

As far as babysitting a cat vs noncat, I'd say you have to babysit both. They both have to be burned hot for a little time to bring up the temp for secondary burn, and you always have to fiddle with the air control to get your burn just the way you want. Plus you have more control with a cat stove because there is no inlet for secondary air.

I figure the savings in the energy bill will pay for any wood stove in a few years, so cost is no object to me. The cat has to be replaced every 3-6 years, but the wood you save pays for that and then some.

Maybe the old cat stoves and the troubled Vermont Castings thing gave the cat stove a bad name? I've noticed alot of good threads and reviews about cat stoves at hearthnet.com, and I think cat stoves will make a comeback.

Todd

Sweepy Hi Todd,

I can easily accept your impression that the new catalytic stove seems to put out more heat than the non-cat it replaced: a quick look at both manufacturers' brochures reveals that the Fireview has a larger firebox than the Homestead, and is therefore rated to produce up to 5,000 more btu/hr. If you were to replace your new Fireview with a stove that had an even larger firebox, you could expect it to put out even more heat for an even longer period of time, regardless of whether it was catalytic or non-catalytic. In other words, your changeout to a larger stove doesn't support your claim that catalytic stoves perform better than non-cats.

Another unsupported claim is that the Fireview puts out more heat while burning less wood. If that were true, your new stove would have to be more efficient than your old stove, and according to both manufacturers' published test lab reports, that simply isn't so: the Fireview is rated at 72% efficiency, and the Homestead is rated at 74% efficiency. Greater efficiency means that with equal loads of wood, the Homestead will produce more heat than the Fireview. Which is just the opposite of what you claim.

I'll agree with you about the patience needed to babysit cold soapstone stoves until the stone heats up, whether they're catalytic or non-catalytic. Since both of your stoves are made of soapstone, and you presumably let them get cold between refuelings, you probably wouldn't notice how much longer it takes catalytic stoves to "light off" as compared to non-cats. Owners of cast iron and plate steel stoves see a much greater difference in warm-up time between cats and non-cats, as documented in the letters above.

Your comment about non-cats having higher flue gas temperatures is a valid one, but the reason for this is that non-cats burn hotter than cats. This means they also radiate more heat into the room. The overwhelming majority of our service customers who have switched from catalytic woodstoves to same-size non-cats have reported an increase in heat output, along with the advantages of slightly higher flue gas temperatures, such as better draft and lower creosote formation.

But again, you're not comparing same-size stoves. If we wanted to stage a fair comparison between catalytic and non-catalytic soapstone woodstoves, the Hearthstone Phoenix would be the closest size to the Woodstock Fireview. The non-catalytic Phoenix has a firebox that is about the same size as the Fireview, and is rated to produce the same maximum btu/hr. Had you replaced your Homestead with a Phoenix instead of the Fireview, you'd have the same higher output and longer burn time you're enjoying now. You'd also have a larger view of the fire, and about $200.00 in your pocket.

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Letter #7: Todd again, still not convinced

Thanks for the reply. I respect your opinion and You have alot of good points. I agree that the bigger the firebox the more wood you can burn, and the more heat and longer burns. But I was assuming the fireboxes of both stoves were simular. Homestead is 2.0 cubic ft and Fireview is 2.18 cubic ft. The homestead claims it can hold 40 lbs of hardwood and the Fireview claims 35 lbs. So they are simular sized.

BTU numbers are only numbers. Who knows for sure how they came up with thoses? EPA or cordwood by independent testing can very the BTU claims of manufactures. Efficiency ratings can be misleading as well. Manufactures can pretty much state what they want, and a few effeciency points or BTU's differences mean nothing to me. You can't just go by the numbers. Too many variables.

As far as light offs is concerned. You still have to burn a non cat hot for 10 to 20 minutes or more before turning it down to a low burn when you refuel to keep that firebox above 1000 degrees for secondary combustion. A cat stove firebox just has to be around 400-500 for the cat to light off.

My test isn't scientific, but I like to say it's real world. By using the same amount of wood (or BTU's) in each firebox. It seems to me that the cat stove out performs the non cat stove hands down. Longer burn times, cleaner burn, more heat, and less wood usage.

Todd

Sweepy Hi Todd,

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.

I tend to use a formula that's been around as long as I have, which relates to only three variables: the size of the firebox, the efficiency rating of the stove, and the duration of the burn. The formula and an explanation appear on our Average Output - 8 Hour Burn comparison page. Here it is:

Mathematicians: In order to compute the heat output of a given wood stove over a given period of time, we need to know the heat value contained in a full load of wood, the efficiency at which the woodstove delivers that heat, and the duration of the burn. We derived our sustained burn comparison figures using the formula below:

( firebox size in cu. in.) x ( 0.015 ) x ( 6200 ) x ( stove efficiency ) / ( burn time )

To get the firebox size in cubic inches, we multiplied the manufacturer's stated cubic foot measurement by 1728.

The 0.015 is the weight of the fuelwood per cubic inch (we used an average of the top 28 species from our firewood comparison chart ).

The 6200 is the BTU (heat) content of the fuelwood per pound, also averaged from our firewood chart, with a slight correction for airspace between wood pieces, because you can't get 2 cubic feet of wood into a 2 cubic foot firebox. Even if you really try.

For stove efficiency, we used the manufacturers' tested rating, not the rating on the EPA label. The EPA doesn't test for efficiency, and there's a disclaimer to that effect on all EPA labels, which, by the way, all show the exact same efficiency rating. Why they even bother to put that number on the labels we don't know, but we do know that all woodstoves don't operate at exactly the same efficiency, so we heed the EPA's disclaimer and disregard it.

For burn time we used 8 hours, which is an industry standard we know all our woodstoves can meet.

Note that the average btu/hr rating derived by this formula does not reflect how the heat is actually delivered over the course of the fire. In the real world, a fresh load of wood delivers much more heat toward the beginning of the fire when the gassified resins are being consumed, then gradually delivers less and less heat as the fire proceeds through the charcoaling process. This actually works out quite well, as it takes more btu's to bring a cold house up to temperature than it does to maintain that temperature.

I don't know why Woodstock figures a fuelwood weight of only 17 lbs/cu.ft when everybody else in the industry seems to use 20 lbs/cu.ft, which happens to be the exact number that comes up if you average the top 28 fuelwood species on our fuelwood chart, but if you multiply the size of their Fireview firebox by the standard number, the Fireview holds about 44 lbs of wood, or about 10% more than the Hearthstone Homestead. Here's how the two models chart up using the formula above:

Manufacturer /
Model

Cat/
Non-Cat

Firebox Size
Cubic Feet

Firebox Size
Cubic Inches

Fuel
Capacity

Efficiency
Rating

BTU/HR
8-hr Burn

Maximum
Output

Woodstock Fireview

Cat

2.18

3767

44 lbs

72%

31,530

55,000

Hearthstone Homestead

Non-Cat

2.00

3456

40 lbs

74%

29,730

50,000

The chart shows it is no surprise that your Fireview burns longer and produces more heat than the smaller Homestead. According to the formula, the Fireview's larger firebox can be expected to average 1,800 more btu/hr over the long burn. Also not surprisingly, the manufacturer says it peaks at 5,000 btu/hr hotter.

Now let's compare the Fireview to the non-catalytic Hearthstone Phoenix, which has almost exactly the same size firebox:

Manufacturer /
Model

Cat/
Non-Cat

Firebox Size
Cubic Feet

Firebox Size
Cubic Inches

Fuel
Capacity

Efficiency
Rating

BTU/HR
8-hr Burn

Maximum
Output

Hearthstone Phoenix

Non-Cat

2.20

3802

44 lbs

72%

31,819

60,000

Woodstock Fireview

Cat

2.18

3767

44 lbs

72%

31,530

55,000

As you can see, had you chosen the non-catalytic Hearthstone Phoenix instead of the same-size catalytic Fireview, you could expect to experience an even greater increase in average btu/hr, and an even higher peak output.

The bottom line is, if you want a fair comparison of catalytic technology to non-catalytic technology, you need to start with two stoves with the same size firebox.

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Letter #8: Long-time woodburner unhappy with new catalytic model

Sirs, I have been burning wood in my home for the last 25 years, starting with an old pot belly stove in the early '80's which I replaced with a (non-catalytic) Vermont Casting Resolute Acclaim that lasted until 2 years ago.

I burn my woodstove 24 hours a day, 7 days a week and go through 7 cords of wood per season. It is my main source of heat, although I have an oil burner that I use as backup.

I thought I was buying a good stove when I purchased a Lennox Earth Stove model 1003C with a catalytic converter. I was told that I would get 8 to 12 hours of burn time.Well, humbug. Six large dry logs on a 3 to 4 inch deep bed of hot coals at 11 pm, and by 3 am the oil burner kicks on as the wood fire dies down and goes out.

The catalytic converter clogs up badly during heavy use and did not last 1 year. I went to many places online and in person to try and get a replacement converter, until finally East Coast Fireplaces here in New Jersey was able to get me one at a price of $360.00 (a bit much, I felt, but I needed the stove working).

Now, the hinges on the door have broken.

I have contacted the dealer that I purchased the stove from and he no longer carries this brand for he says they do not return his calls. I have sent many emails to Lennox and have had no satisfaction whatsoever with them.

Is there a stove that will actually hold up to being used 24/7? From what I have experienced, all the nonsense of burn time is a farce: am I wrong? I am interested in what you may have experienced, and in any info you have regarding something better than what I have. Thank You for your time.

Bruce Normand
Freehold, New Jersey

Sweepy Hi Bruce,

As you may have gathered, we're not big fans of catalytic woodstoves, but must admit that, aside from the need to periodically clean and replace the converter, most cats seem to hold up to 24/7 burning every bit as well as non-cats. We think the issue here might be twofold:

First, it sounds like you didn't remove and clean your converter at least once during the burning season, as required in your owner's manual . This is a big hassle when you're burning 24/7, but might have prolonged the life of your $360.00 catalytic converter considerably. With proper burning and maintenance, Lennox claims their converter should last 10,000 -12,000 hours, which is 416 - 500 days. Figuring a 6-month burning season, with proper maintenance your converter should have lasted about 2-1/2 years.

Second, you might have chosen too small a stove for your heating needs. The 1003C peaks at 51,000 btu/hr, and thus must work pretty hard to heat an entire house throughout a New Jersey winter. Having too small a stove will not only create short burn times such as you describe, but will often lead to overfiring in colder weather, which may well be what toasted your door hinges.

You might have guessed we'd recommend you replace your 1003C with a non-catalytic stove, but we also recommend you look into a larger model that won't have to work so hard to heat your house. In our lineup, we feel you should consider the Pacific Summit and the Hearthstone Mansfield. Both are non-catalytic, both easily hold a fire all night, both are intended for 24/7 burning, and both have lifetime warrantees that cover the entire firebox assembly, including the door hinges.

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Letter #11: Intrepid II owner happy with his stove!

Sirs,

From time to time I get the urge to buy a woodstove which takes longer logs than the Vermont Castings Intrepid II (catalytic) which I have used for the past 10-12 years. I came across your catalytic vs non-catalytic discussion by chance, & here is my contribution.

I burn 2-3 cords of wood in a cold winter, mainly to keep a kitchen wing in our 19th C. farmhouse warm. I burn ash, tulip poplar, or white oak (my preference). I stoke the stove at 9-11pm, lower the air supply to just above the minimum, & at 6:30 am there are plenty of coals to start up fresh logs. Usually, but not always, the stove temperature is still high enough to keep the catalyst going. The airflow is so low that I don't think I can be polluting much the last couple of hours when it isn't, but it is probably no different from a low temperature burn in a non-cat stove.

I have replaced the catalyst once, when I noticed that engaging it no longer caused the temperature in the stove to rise. It's easy to tell when it is working, too, because the smoke smells different. Once or twice a season I open the back of the stove to knock the ashes off the honeycomb when I notice performance is deteriorating (this takes about 15 minutes, because the stove is in a fireplace & it is awkward to get the 2 bolts off the back).

From a cold start, it does take about an hour to get the stove warm enough to light the catalyst, but I don't do many cold starts & when I do, I'm busy in the kitchen anyway, so I'm not really losing time.

I compared the specs on your non-cat Tribute stove with those of the Intrepid II since they are about the same size, & for what they are worth, the catalytic stove is 11% more efficient (81% vs 73%) and emits 38% less particulates (2.1 g vs 2.9g-- this could be partly a function of burn level, since the tribute is rated at max 36,000 BTU vs. the VC 26,000--I don't know whether particulates are normalized to heat output or not).

If I lived on the West Coast, I might well buy a locally made, not-catalytic stove. But it does seem to me that as a rule the catalytic stoves are significantly more efficient (the Defiant cat is rated at 0.81 g particulates/hour, if it's not a misprint) & higher efficiency translates not only to less firewood expense but also longer burn for the same heat, fewer trips to the woodpile and, very important, less air pollution. We pay extra for cataytic converters on our cars to reduce pollution, so I hardly think we need to justify the cost of a catalyst by firewood saved. And in a decade of use, I have had none of the maintenance problems described by some of your correspondents.

Sincerely,
Michael Showe
Media, Pennsylvania

Sweepy Hi Michael,

Thanks for the input! But c'mon, servicing your catalytic converter takes just 15 minutes? Realistically, shouldn't you factor in the time it takes for your fire to go out and your converter to cool down before you can start, the considerable time it often takes to wrestle with heat-frozen mounting hardware, and the time spent cleaning the soot off your hands, clothes, and the area surrounding the stove when you're done? I've tackled that job, and at best it's a messy, several-hour hassle.

When comparing stoves, it is important to remember two things: first, lower emissions ratings do not translate into higher heating efficiency, and second, the EPA requires catalytic woodstoves to burn cleaner than non-cats during emissions testing, because the catalytic converter becomes progressively less effective as time goes on. The Intrepid II must test at 2.1 grams/hr when new, in order to average less than 7.5 grams (the standard for non-cats) over its projected 3-5 year lifespan. During its final year of use, your catalytic converter could allow emissions several times higher than the levels printed on the EPA label when it was new. Meanwhile, a non-cat rated at 2.9 grams/hr can be expected to retain that emissions level throughout the entire lifespan of the stove.

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Letter #12: Earth Stove Catalytic owner says vinegar bath restored converter

Hi, I live in Fairbanks, Alaska. I have used many variations of wood burning stoves. Now, I heat my 1000 sq.ft. house with an Earth Stove 1003C (a catalytic converter model ). I must say that it is the easiest and most consistent stove I have used so far. Mine is six years old, never goes out ( well not much ) all winter. The heating season is about six months here.

I vacuum the cat occasionaly, and recently washed it out with an vinegar/water bath. Nothing complicated. That returned it to its original performance level. The instructions mention this as a good idea when they get older. I do not see that as a drawback, considering the incredible efficiency and obvious environmental benefits.

I read the comments on your website regarding these type of stoves. What can I say, my experience has been very good. Sure, like anything it takes a little getting used to. But we are not talking rocket science. Mostly common sense and patience. I do not really put a lot of weight in the comparative 'facts'. Suffice to say these type of units are valued here, where the season is long and benefits are easily observed. Some of the horror stories in this site sound like poor operation. We are basicly putting a modern spin on antique technology , the point is there still is a little skill involved in their use. I'd love to hear more from this site and would be delighted to answer any questions re; how this works, etc.

Sincerely,
Andy Blossy

Sweepy Hi Andy,

Thanks for the input! I'm glad you're happy with your catalytic woodstove, but it seems you might be missing some of the points made in the letters and responses above:

We're not saying that catalytic woodstoves don't do the job they're designed to do. Like non-cats, they turn wood into heat while producing extremely low particulate emissions. The point we're trying to make is, they DON'T do a BETTER job than non-cats, yet they tend to be more expensive to buy and maintain, and more of a hassle to operate.

Non-catalytic EPA approved woodstoves offer the same efficiency and environmental benefits as catalytic models. In fact, the 72% efficiency rating of your catalytic 1003C is middle-of-the-road for non-cats, as is its 3.7 grams/hr emissions rating (particularly when you take into account the fact that catalytic stoves become less clean-burning before they stop working altogether).

Non-cats don't require the operator to vacuum anything, wash anything in vinegar, or replace the converter when, inevitably, it dies. Some catalytic stove owners gloss over these extra maintenance requirements, but as the owner of a non-cat, I would personally consider it an enormous inconvenience to have to let my stove go out and cool down so I could spend the time to vacuum, wash or replace the converter. Aside from cleaning the chimney, the only maintenance I've had to perform on my non-cat stove in over 14 years is to replace the door gasket.

The "longer burn time" catalytic stove owners brag about doesn't hold true against all non-cats. My non-cat has just a 2 cu.ft. firebox, and holds a fire for 10-12 hours while heating my house nicely.

Non-cats tend to produce more heat from the same load of fuel. Your 1003C has a 3 cu.ft. firebox, yet in independent laboratory testing it produced a maximum of 51,000 btu/hr. Non-cats with the same size fireboxes produce up to 97,000 btu/hr in the same tests, performed in the same laboratories. The 2 cu.ft. firebox in my stove is just 2/3 the size of yours, yet tested at maximum 67,000 btu/hr.

For these and other reasons, woodstove manufacturers and the buying public have been moving away from catalytic technology for over a decade. Case in point: (A) Your 1003C was discontinued by Earth Stove in 2005; (B) despite all-time record woodstove sales in the years since, the stock on hand at that time still hasn't sold out.

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Letter #13: Andy responds

Hello Tom, Andy Blossy here. Thanks for the input re: cat stoves. You make a good case for non-cat units. That is fine. I am in the process of re-evaluating anyway, I am always looking for more efficiency. The cat I have has worked well for me, but there is no reason why something may not be better! Up here the more the better re btus etc. So, what would you recommend for an alternative? A biggie here is the Blaze King, unfortunately it is a cat unit. If you have the time I'd appreciate more of your information. Thanks for the feedback.

Sincerely,
Andy Blossy

Sweepy Hi Andy,

For a 1,000 sq.ft. house in Fairbanks, you can't do better than Pacific Energy's Super Series firebox, available in five different models which may be viewed by clicking the thumbnail photos on our Super Series page. I heat my house with a Spectrum.

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Letter #14: Switching from Catalytic Defiant to non-Catalytic version: October 17, 2007

I found your website on a search for Cat vs. Non-Cat. I purchased a VC Defiant Encore w/Cat when it first came out and then upgraded to a Defiant Cat when they came out with that. I've found that they (as you say) are really high maintenance. Fly ash is always getting into the honeycomb and clogging it up.

I did experience whuffing when the CAT got plugged; mostly puffing smoke into the room through the seams where cement had loosened and then blown through. One thing about these stoves is that they will burn pretty well even with a poorly performing Cat; but, as with most, you have to keep the burn temp up there. My primary observation of that is no smoke out the chimney and little build up in it.

I start my stove around Nov 1st and shut it down around April depending on weather (seldom have to use kindling). It can become a real pain for me to have to stop for cleaning (as you point out in one of your library pieces). I considered just tossing the CAT and running without it; but when they came out with a non-Cat Defiant I thought that would be a solution.

After looking for a year or so, I found one that had been used only a few times, for one season (and even though like new it was less than 1/2 price). The reason the owner was selling it was because it was way too large for the application: he had run it damped down all the time, as evidenced by creosote buildup in the secondary burn chamber and s/s flue. I'm going to install it in the next week or so and be rid of catalytic converter hassles forever!

Anyway, I was curious about what others had experienced and your site provides a wealth of info.; I wish that every wood stove dealer knew about your site and gave the link to customers to help them (because it would).

I have to admit, your cast-iron products look really nice and if this does not work out, you and they are on my list!

You are forever bookmarked on my system and it is good to have someone knowledgeable to rely on!

Thanks,
Steve.

Sweepy Hi Steve,

Thanks for the kind words! Here's a chance to help out your fellow woodstove consumers: how about sending in a comparison report after you've burned your non-cat for a few months? Comparison data between cat and non-cat versions of the same stove is hard to come by (let alone any reviews at all of the "Everburn" downdraft technology used in VC's non-cat version of the Defiant), and your experience would be great to share.

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Letter #14 Update, via PM at www.hearth.com: March 12, 2008

About that review on the Vermont Castings "Everburn" non-cat; two words suffice: stay away.

Steve

Sweepy To read the entire story of Steve's experience with VC's non-catalytic Everburn Defiant on the hearth.com forum, click here. Editor's note: Steve is now happily heating his home with a Hearthstone Mansfield.

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Letter #15: Has better experience with catalytic cast iron stove than with non-cat soapstone stove

Maybe I'm not looking at it right, but I've had a Defiant with catalytic element in my home since 1989. It moves to operating temperature quickly, holds a fire for a very long time, and has been generally fine. We've used it for only 30-50 days a year, unlike the old days when we heated with wood exclusively, first with an Ashley and then with a large Jotul. I can't detect any need for a new cumbustor. That might have to do with a consistent, dry supply of hardwood over the years.

In contrast, I have a large non-catalytic side and front loading Hearthstone stove in a vacation home. It is incredibly difficult to get going and keep going without constant fiddling with the doors, ash pan in addition to the draft control, plus spoon feeding until it finally gets there. Might take two hours. The installation and chimney are correct. The stove just doesn't know how to breathe.

Reading your other letters, it seems like my experience is either truly ignorant or truly unique.

Bruce N.
Lambertville, NJ and Chappaquiddick, MA

Sweepy Hi Bruce,

Thanks for sharing! Your experience is somewhat unique, in that you don't seem to use either of your present woodstoves very much, but nonetheless it pretty much jibes with the experiences reported by mainstream woodburners with the same stoves.

The catalytic converter in your Defiant is warranted by the manufacturer to last 6 years. With a presumed typical usage rate of 5 months per year, that comes to 21,600 burn hours. Since you only burn your stove an average of 40 days per year, your converter has only logged in about 16,000 hours or so: according to the manufacturer, it should last another 5,000 burn hours until you absolutely need to replace it. In contrast, the typical woodburner who has relied upon a 1989 vintage Defiant to heat his house all 5 Winter months for 18 years would be on his 4th catalytic converter by now, and would likely have rebuilt his stove at least once. Most of the complaints we hear tend to come from these folks.

Tip: to optimize performance and minimize airborne pollutants, you might consider replacing your catalytic converter before it finally dies. Even though you can't detect any need for a new cumbustor, yours has deteriorated steadily over 16,000 hours of use, and will be less effective than it was when new.

A soapstone stove would be my last recommendation for occasional use, such as in a vacation home. The engine of every woodburning system is the chimney: no woodstove will "breathe" properly until enough heat enters the chimney to get an updraft established. And therein lies your problem: chimneys venting soapstone stoves don't even start to draft properly until the stove warms up to the point where the stones stop absorbing so much of the heat from the fire. As you've already discovered, it can take a couple of hours to get a cold, 500 lb. soapstone stove and its chimney up to optimum operating temperature. Our most satisfied soapstone stove customers are folks who light a fire in the Fall and feed it until Spring, never letting the stones get cold.

Tip: for a vacation home, the best choice is usually a woodstove that gets its engine going quickly: a non-catalytic plate steel model would be ideal. If you're going to keep your present stove, you'll find some info about getting a cold soapstone stove going in our online Sweep's Library by clicking here.

Another idea: taller, properly-sized chimneys tend to warm up faster and draft better. If your vacation home stove isn't connected to a 6" round chimney extending straight up at least 15 feet, a chimney modification might help you get your fire going faster.

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Letter #16: Bruce responds

Great response. I've definitely learned a lot in the past minute. You, sir, are the real thing! Thanks very much.

Bruce

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Letter #17: A happy catalytic stove owner

Hi chimneysweeponline

I have enjoyed reading your Letters: Catalytic vs Non-Catalytic Woodstoves comments.

I have been burning wood for heat since 1981. I have used/owned Jotul stoves (602, 118) Morso (squirrel) and Vermont castings stoves. (Defiant 1, vigilant, intrepid 1, Fireplace insert #0044, Dauntless)

I now use 2 VC stoves. An early Defiant Encore Cat. and an Intrepid 2 cat. I can vouch that the quality of the VC stoves in fit and finish seems to have suffered somewhat but my experience with my VC cat stoves has been very good. I have no trouble with getting them going and am happy with their overall performance. I have been burning the Intrepid 2 cat. nearly 24/7 in winter since 2000 to heat a 1200 sq.ft house. The combuster has some wear as does the combustion chamber. But it is still operational and I am surprised at that, as I imagine you might be from reading your notes. Compared to the Intrepid 1 I do use far less wood and the creosote build up is very minimal. The stove works great and I would recommend it.

I am a careful wood burner. I cut my own wood and burn it seasoned & dry. My stove is set up well. A good stainless steel liner in an indoor masonry chimney creates a good draft, and all the stovepipe from the stove to the chimney is sealed tightly. I clean out the convertor 2x per winter. It is easy and takes half hour at most. Mind you this is a newer Intrepid where you need not take the convertor out of the back of the stove which is more cumbersome. The new one is 2 bolts inside the stove and the plate comes right off.

I understand your reasonable argument regarding replacement and maintainance of catalytic convertors but I have definitely gotten my money's worth from these stoves.

I have not tried any new non-cat stove but from your comments I may consider one.

Thank You,
Steven (Berkshires, MA.)

Sweepy Hi Steven,
You've owned 11 different wood stoves in the last 27 years, and are considering another one? Man, you've got to get a handle on this buying spree before you exhaust the supply of cast iron in Berkshires, MA!

Seriously, I thank you for your (very) experienced input.

 

Letter #18: Catalytic model difficult to operate

 Hi,
Feel free to ignore me, but I just feel the need to vent my frustration over my cat stove and I can literally find no online presence other than you who doesn't seem to think they are wonderful. So easy, so efficient, so long-burning, so much more heat from your wood. As far as I can tell that is a load of crap. I have been busting my ass for three years now to figure out how I can get this stove to do what they all say it does continuously and automatically, and I think I know the answer: Burn only kiln-dried wood in it. Give the fire enough air to burn relatively clean on its own, and you fry the cat. Try to protect the cat, and half the time you find your stove temp down in the 200's and it takes half an hour to get it back on track. Unless you have perfectly dry wood, of course. But in the real world, each load of wood has a slightly different moisture content, and a percentage point this way or that seems to tip the stove one way or the other. With a non-cat stove, if I burn the wood at full flame like I would in a pre-EPA stove, it doesn't matter to the secondary air tubes. When they burn smoke they are just as hot. This system seems much more flexible and less fragile than the cat system, am I right? And it seems to me that the cat stove makers have neglected one of the three crucial ingredients of combustion: oxygen. Maybe if there were a secondary source of oxygen for the combustor, it wouldn't keep going out. Anyway, in the spring I am getting rid of this thing and replacing it with a non-cat model. That way I just have to make sure the wood is burning and I know the stove will do what it is supposed to do. Thanks for listening.
Adam
Oh, and I just have to complain about one other thing. This is a Woodstock Fireview I'm ranting about, and when they first designed it, it was a top loader with side venting, so air flowed along the logs lengthwise from the bottom. Good airflow, good predictable firebox heating. Now, you load it through an undersized side door, and air flows from the top front against the side of the logs. The smoke exits right next to where the air enters, so as you can imagine that part of the stove has no trouble getting hot, but just TRY to get the lower rear of the stove hot without overfiring the combustor! Just try it someday!

 

Sweepy Hi Adam,
Thanks for the input!  I must agree with your comments about fireboxes that are designed to deliver the combustion air against the side of the logs, which are loaded East-West.  These tend to be more difficult to get going, and seem to produce more unburned "clinkers" than stoves designed for axial combustion (where the logs are loaded North-South so the combustion air is delivered to the endgrain, causing the logs to burn cigar style, front to rear).  The root of the problem is the airwash design incorporated in today's stoves, which causes the incoming combusion air to flow down across the inside of the viewing window to keep it from sooting up.  The viewing window is always on the front of the stove, so in East-West designs, the air flows against the side of the logs.

 One solution you might try is to cut your wood short enough so you can load it North-South.  Unfortunately, this isn't always practical if the stove is particularly shallow.

 

Letter #19: Tired of replacing converters

Good morning.  If you don't mind taking a minute or two to answer a question, I have a VC Defiant, that is 13 years old. I must have replaced my catalytic converter 4x. Now all of the refractory gaskets that hold it in place are deteriorated. To be honest, I'm tired of this woodstove, how every year I have to put a couple hundred dollars into it. My question is, have you guys come across any owners of this stove, who have said the heck with the catalyst, and removed it, installed a manual damper in the flue pipe, and just ran it like an old fashioned woodstove?

Thanks for your time,
Frank

Sweepy Hi Frank,

We've heard from several people who decided not to replace a burned-out converter over the years, but none kept burning that way for very long. The catalyst causes the exhuast from the main fire to reburn, providing about 50% of the net heat into the room. Remove the converter, and you'll instantly start burning twice the wood to heat the same area.

       

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