More "cat vs. non-cat" literature

[Ashful]

Came across this very informative article:

http://www.hearthandhome.com/James Houck Articles/HH_11_February.Catalytic Comeback.pdf

Some very interesteresting quotes, some surprising, some already common knowledge:

"On average, catalytic heaters have lower particulate emissions than non-catalytic heaters"

"most modern certified non-catalytic stoves have smaller fireboxes because it is more difficult to reduce particulate emissions low enough to be EPA certified if the firebox becomes too large... This is not the issue with catalytic technology; these are heaters with larger fireboxes that can be certified more easily."

"What is not just a marketing claim, and generally accepted, is that, as a group, catalytic wood heaters are more efficient than non-catalytic wood heaters."

"well-designed, modern catalytic wood stoves "protect" the catalyst from thermal stress and direct flame impingement, and... tests suggest that catalyst degradation in a well-designed stove is not an issue." (I personally have some doubts on this particular claim.)

"the mean emission factors for catalytic stoves were much lower than for non-catalytic stoves at the lower burn-rate categories, suggesting a disproportionately better performance of catalytic stoves than non-catalytic stoves at lower burn rates."

 

[StihlHead]

Well, as you suspect, that is in contrast to the conclusions of this rather well studied paper that was done back in 1998. This report claims in all their extensive tests, catalytic stoves all degraded significantly over time, and in many cases far more than non-cat EPA stoves. They also concluded that any stove that is heavilly used will degrade faster than one that has less use (EPA cat or EPA non-cat). When they took the average (mean) of all the stoves tested over the duration of many years of testing done at many locations throughout the US and Canada, the non-cat stoves actually performed better (in regard to emissions released) over time by a slight margin. Given the cost difference of available stoves and the added cost to replace cats, I went with a non-cat stove.

http://www.epa.gov/ttnchie1/ap42/ch01/related/woodstove.pdf

 

[Ashful]

Not saying you're not 100% correct, but that's an article on "the state of the art" as it stood 14 years ago. The claim in question pertains solely to newer catalytic stoves.

I do believe the claim on having significantly better efficiency at lower burn rates is well-confirmed, at this point.

My goal, still unfulfilled, is finding an attractive, new, reliable, front- or top-loading catalytic stove with top-exit flue. I'm finding stoves that hit a few of those marks, but none hit them all.

 

[mellow]

Just more fodder for the cat vs tubes fight.

Burn with what you think is best for you. Both technologies will keep you warm.

 

[Ashful]

Just more fodder for the cat vs tubes fight.

Never knew there was a "fight"! I couldn't care less what stove anyone else chooses. Some more info on the pro's and con's never hurts in making a decision, though.

I also never cared about Ford vs. Chevy vs. Dodge. I've owned all three, in that order.

 

[Todd]

Bottom line is both technologies have their advantages and lately manufactures are incorporating both into one stove and calling it a hybrid.

 

[Highbeam]

I predict that the hybrib approach is a bust. So far you get neither the cheap and simple non-cat operation, nor the long low burns, worst of both worlds.

 

[Ashful]

I predict that the hybrib approach is a bust. So far you get neither the cheap and simple non-cat operation, nor the long low burns, worst of both worlds.

I fear you may be correct. I'm certainly not sold on the new Lopi hybrid system, if the description I received is at all accurate. The VC system seems much better... in theory. Gotta wait until some of the users confirm that reality aligns with the theory.

 

[StihlHead]

Not saying you're not 100% correct, but that's an article on "the state of the art" as it stood 14 years ago. The claim in question pertains solely to newer catalytic stoves.

I do believe the claim on having significantly better efficiency at lower burn rates is well-confirmed, at this point.

My goal, still unfulfilled, is finding an attractive, new, reliable, front- or top-loading catalytic stove with top-exit flue. I'm finding stoves that hit a few of those marks, but none hit them all.

First off I am not saying that cat or non-cat stoves are any better than the other. Actually the report I posted said that they are basically the same over time. Also the CHC report tested two stove types (maybe they just tested two stoves? which would mean the results are not well substantiated). Of the two stove types, one was 9 years old and the other was 5-1/2 years old. So I do not see how a 14 year old report is somehow way out of line here. Actually, they are contradicting themselves in the CHC report saying that modern "state of the art" cat stoves are great, while reporting the results of testing nine year old cat stoves. ???? They also do not mention how much those stoves were used, and the sample was so small as to be completely useless in any scientific sampling method. I am at a loss to connect the tests and the statements made in their report with such a vague and small testing sample.

The main point in the testing report that I posted is that cats fade in effectiveness over time, and thus the original cleaner burning and higher efficiency aspects are reduced with age (in the wide number of models tested). Over time, cat stoves actually become slightly less efficient than non-cat EPA stoves. The CHC report also make statements about newer design cat stoves protecting the cats better to avoid degredation, but they do not support that with any evidence that I can see (other than the two stove models that they tested). They do make a much better case about cat stoves being better during cold firing, though they also use some average of stoves only burning 7 hours a day. I burn 24/7 for 5 months a year, and maybe 9 hours a day during the shoulder seasons. I do not burn for about 3 months a year (July, Aug. and Sept.).

Me, I am a NC guy. I got an Englander NC 30 becasue I had to have an EPA II stove that was also HUD approved, had an OAK option (I am an OAK fan, but that is another debate) and a pedistal, fit in my existing space, and was cheap.

 

[Ashful]

Good points, StihlHead. This report, coming from the CHC, should definitely be read with a skeptical eye.