Are Condar steel catalytic combustors good??

Jim, I can't answer to the specifics of your stove but I've heard good things about the steel cats. Our next one will be a steel. One nice thing is they will ignite at a lower temperature. Should last longer but only time will tell on that.

I switched to a steel cat from Condar a while back and have been very pleased with it so far. It definitely lights off faster and so far I have had no problems with it. We will see if it makes it the four to five years that my porcelain ones usually did.

Anyone else have experience with the steel cats?

I just purchased a BK Princess Insert, it has the ceramic cat in it. All 3 of the inserts they had on hand had ceramic cats in them.

I picked the sales mans brain about cats. He said that BK was sending stoves with either cat. He said they asked BK if they could just send stoves with steel cats, but BK said they couldn't do that for some reason. He said BK is going back to using all ceramic cats. He also said they have had a few issues with the steel cats plugging, but that it was due to operator error (burning unseasoned wood).

My 2003 BK King has a ceramic cat in it that is getting pretty tired. I just learned about a woodstove repair program our town is having, so I was going to get a new cat for the King.

Should I go with the ceramic or steel? I'm thinking ceramic.

I'm also curious about Steel Cats... I like the idea of a lower light off temp since my one complaint with my stove (keeping in mind that my wood is marginal as a first year burner) is when I load it up for an overnight burn and have to wait for it to get to temp if I let the stove get too cold and I'm ready for bed... A couple of nights I've ended up staying up much later than I wanted because I put in a unseasoned piece of wood.

Speaking of which.. I better load up my stove now if I want to get to bed at a decent hour.

Woodstock switched all their stoves to steel cats so that's what I'll purchase when the time comes. They are relatively new so they may have a few kinks in them yet but I like the fact that they lite off sooner and are resistant to thermo shock. This also tells me cats aren't going away anytime soon like some people claim if they are looking into improvements in cat technology.

Good to know Jim. Thanks.

mtek said:

Just wanted to let everyone that is interested that I purchased a steel cat from Condar and have been amazed at the effect on the stove. I use much less wood. (Almost half as much) It lasts a lot longer and the overall burn is more even. I would recommend a steel cat to anyone.


Jim

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Thanks Jim, excellent to know.

To add to the information, what was the age & condition of your old cat? Do you think it was pretty incapacitated?

Has anyone here purchased a BK that had a steel cat?

mtek said:

RenovationGeorge said:

To add to the information, what was the age & condition of your old cat? Do you think it was pretty incapacitated?

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Unfortunately I have no exact information regarding the age of the old cat other than to say that the stove had been neglected by the previous homeowner. I suspect that, given the difference in performance, that it was well and truly beyond it's service life.

Without wishing to seem to be repeating myself the new cat has created another problem. I can go so long between stocking the fire-box that I have forgotten to do it twice already!!


Jim

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Nobody knows the troubles you've seen! Congrats.

What stove are you burning? EDIT--oops, you said, I missed it. (If you put it in your sig, we'll always know.)

mtek said:

It's a Lopi Flex-95 which I think was installed in the early to mid-nineties. The previous owner had neglected it very badly.

I updated my signature as suggested!

Jim

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You da man!

Sorry I missed it in your original post. Thanks for the report on steel cats.

Guys, metallic catalysts are nothing new. A search using "emitec" as "assignee" on the USPTO website reveals 275 patents, with the first applicable one being filed in Germany in 1987. Metallic catalysts have been considered "premium" catalysts for a long time and going back to the early 2000's you would find them under the hood of every Porsche and BMW built. One of the key features is that the corrugated wall can be made much thinner than what is production feasible for ceramic slurry. The steel is of a special type which includes aluminum in the alloy. When this is baked in an oven for an extended period at very high temperature some of the aluminum comes out to the surface and forms alumina (oxide). This oxide was key to having a surface to which catalytic coatings would adhere. Previous attempts were unsuccessful or not durable.

Because of the relative expense compared to extruded ceramic (not counting the platinum and palladium coatings) they tended to be used only where a sufficiently large ceramic catalyst couldn't fit and a smaller diameter catalyst with the same back pressure was needed. Or alternatively, they were used if the performance advantages (reduced back pressure for maximum engine performance) were considered to justify the price. Due to their design, they were also relatively easy to integrate into an exhaust system, since one basically welds then onto the inlet and outlet cone with no other material being needed.

In the late 90's various DOT and other regulations began to have an impact on the way various vehicle sub systems (abs, traction control, stability control) were able to interrupt the "normal" command of the engine controllers. Basically, due to suv rollover problems and other handling issues, priority for "safety" related overrides of normal engine controls increased and engine and emission system survival took a bit more of a back seat (not that it didn't matter with 10 year mandated federal durability of the emissions system). This hit the performance vehicles particularly hard, since the owners of said vehicles were precisely the operators that would be inclined to push the system to its limits "for fun". The resulting "lack of control" relatively speaking changed the way these systems were tested and the result from the new testing was that in less controlled environment the metallic catalysts were not as durable and there was concern they would not meet mandated durability requirements. In many instances there was a switch back to ceramic catalysts, which had very significant implications, since the manufacturers had to physically make more space available in the engine compartment or alternatively resort to some very unusual design alternatives. The Porsche Boxster for example, was one such project I worked on where the first catalyst was embedded in the exhaust manifold and the second inside the muffler. Both applications operating in extreme environments with average temperatures close to 1000C. This kind of application had never been done before with a ceramic catalyst, but with the right materials and design it was more durable and cheaper than the metallic system.

Having said all of that, we wood stove owners pay a relatively large amount of money for our catalysts compared to the cheap and dirty car makers. And the warranty liability in our application is virtually zero. So it could be that the manufacturers of the metallic catalysts saw a gap in the market to increase sales. Some of the original patents may also have expired and people may be making copies of the Emitec designs. It is possible, since wood stove burning is not a highly controlled art, that durability will ultimately be worse. They work great initially of course. If you burn dry wood and avoid overfiring, you may be fine. Most people don't realize that a flue gas thermometer only gives the average temperature of the gas. When burning hydrocarbons in the cat the local temperature can get high enough to melt platinum, but the reaction may only be occurring in 5% of the catalyst volume at any given instant. Usually, 90% of the reaction has occurred in the first 1/4" of the catalyst length with a new cat. As the cat ages, the "active zone" moves deeper towards the outlet as the heat of the reaction ultimately destroys the function of the coating.

BK may have found out what Porsche already knew and made the switch back to ceramic for that reason. If the catalysts are price competitive, slightly shorter life may be acceptable, or if you are low on draft you may find a less restrictive catalyst to be just the ticket.

Interesting. I'm just having a hard time turning my King into a Porsche. Performance aside, I feel at times as though I'm chucking wood into a big, hot washing machine. (working on that aspect of it though...) Thanks KeithO.

KeithO, thanks for the input, I'll have to look more into that. Maybe a phone call to BK is in order to see what they have to say.

kgrant said:

KeithO, thanks for the input, I'll have to look more into that. Maybe a phone call to BK is in order to see what they have to say.

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That would be interesting. Please post back if you do!

KeithO -

Thanks for edjumakation of cats! I would have thought it would be the other way around - steel being cheaper than ceramics. And as how they "die" makes more sense to me now.

KeithO said:

When burning hydrocarbons in the cat the local temperature can get high enough to melt platinum, but the reaction may only be occurring in 5% of the catalyst volume at any given instant. Usually, 90% of the reaction has occurred in the first 1/4" of the catalyst length with a new cat. As the cat ages, the "active zone" moves deeper towards the outlet as the heat of the reaction ultimately destroys the function of the coating.

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What about potassium? We had some guys visit Woodstock last Summer and they heard some info about potassium from wood burning is what kills the cat over time more than anything else? Something about a chemical reaction with the catalyst? They also mentioned some kind of metal that could neutralize the potassium before it enters the cat and give it a much longer life?

kgrant said:

Anyone else have experience with the steel cats?

I just purchased a BK Princess Insert, it has the ceramic cat in it. All 3 of the inserts they had on hand had ceramic cats in them.

I picked the sales mans brain about cats. He said that BK was sending stoves with either cat. He said they asked BK if they could just send stoves with steel cats, but BK said they couldn't do that for some reason. He said BK is going back to using all ceramic cats. He also said they have had a few issues with the steel cats plugging, but that it was due to operator error (burning unseasoned wood).

My 2003 BK King has a ceramic cat in it that is getting pretty tired. I just learned about a woodstove repair program our town is having, so I was going to get a new cat for the King.

Should I go with the ceramic or steel? I'm thinking ceramic.

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I asked Chris at BK headquarter this question, seems they have had very positive results using the ceramics with the princess models.

Todd, I'm not a chemist and I am not personally involved in the coatings. I have not heard of the potassium issue. Doing a google search on "platinum catalyst poisoning" brought up some text from a power generation handbook and it seemed that potassium may be a problem with NOx reduction catalysts.

Considering that in automotive applications, catalysts are "normally" only expected to process hydrocarbons in the parts per million range (that is what engine controls are for and it reduces the size of catalyst needed and thereby the expense). In a cat stove, the level of hydrocarbons is probably more in the 1:10 to 1:100 range, so you have a brutal exotherm (reaction which is releasing heat) for probably 50% or more of the operating time of the stove. After the volatiles have burnt off, the cat will be burning CO to yield CO2, but that is a milder reaction. And of course, the flue gas is anything but "clean" so I'm sure there is some poisoning going on too. But the thermal side of things I think is sufficiently severe to guarantee the catalyst being "worn out" within about 5 years (obviously depending how much you burn).

Todd said:

KeithO said:

When burning hydrocarbons in the cat the local temperature can get high enough to melt platinum, but the reaction may only be occurring in 5% of the catalyst volume at any given instant. Usually, 90% of the reaction has occurred in the first 1/4" of the catalyst length with a new cat. As the cat ages, the "active zone" moves deeper towards the outlet as the heat of the reaction ultimately destroys the function of the coating.

Click to expand...

What about potassium? We had some guys visit Woodstock last Summer and they heard some info about potassium from wood burning is what kills the cat over time more than anything else? Something about a chemical reaction with the catalyst? They also mentioned some kind of metal that could neutralize the potassium before it enters the cat and give it a much longer life?

Click to expand...

Todd said:

What about potassium? We had some guys visit Woodstock last Summer and they heard some info about potassium from wood burning is what kills the cat over time more than anything else? Something about a chemical reaction with the catalyst?

Click to expand...

I saw one cat manual that includes driftwood in it's list of Forbidden Fuels. Seems the salt kills the cat.

The driftwood issue is not just about the cat. Any form of salt in your stove will certainly reduce its life and lead to enhanced corrosion and attack. Even stainless steel may not be resistant above a certain temperature. Its just a warranty issue. People living in some parts of Alaska may not have any options, but they simply have to factor in that there will be more wear and tear on the stove from salt, along with the inherent wear and tear from such a long severe heating season. Making entire stove bodies out of high grade stainless steel is expensive and the 50% higher coefficient of expansion of the 300 series stainless leads to significant expansion, contraction and potential warpage issues too.

mtek said:

RenovationGeorge said:

To add to the information, what was the age & condition of your old cat? Do you think it was pretty incapacitated?

Click to expand...

Unfortunately I have no exact information regarding the age of the old cat other than to say that the stove had been neglected by the previous homeowner. I suspect that, given the difference in performance, that it was well and truly beyond it's service life.

Without wishing to seem to be repeating myself the new cat has created another problem. I can go so long between stocking the fire-box that I have forgotten to do it twice already!!


Jim

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Jim, don't worry a bit about this. Your backside will begin to cool off dramatically.....and then you will remember to stock that thing up!