Catalytic stove question

[Ohiowoodguy]

The honeycomb ceramic catalysts in our High Valley stove seem to plug with fly ash quite often. Do any of you use the new metal catalysts and do they resist plugging-up as advertised? I burn very dry wood, and don't engage the catalist until temp reads 600.

 

[logbutcher]

Let's take a stab at this. But I gotta watch out for the lurker pros (humbolts:soldier waiting for the chance to virtual flame. Here goes:

We've used cat stoves since Vermont Castings introduced them as part of an engineered wood stove in 1989. Like the ones in your truck, they have a limited life.

The ceramic catalysts last for about 12,000 hours ( +/- 2 years of 24/7 hard use) before the paladium or platinum coating wears off and/or the ceramic starts to crack.

I put in a steel cat last winter for our normal 2-3 season replacement. Good so far with just the usual brush-off cleaning. The company, Sud Chemie, says that the metal cat will "light off" at lower temps ( ~ 400 F ) and take higher temps without breaking up like the ceramic cats, and lst longer. We'll see.

So if your cat is well over the 12,000 hour life, replace it. Another way is to do the recommended (Corning) " vinegar bath" to restore the cat . A PITA.

We have a cat and non-cat stoves for heating. The cat stove holds a longer fire, use less wood for the same BTUs, and allow the stove to be damped way down overnight. Butt: cats demand more care and maintenance. Non cat stoves like our Oslo don't allow the air to be very low or very high---a mommie approach for clean burning.

Long way of saying: it's time to replace the cat if it's been in for a few years and used hard. To check the cat operation, get the stove hot ( 600-700 F on top), damper in the cat, then let the temp go back up before lowering the primary air. Then run outside (clothes on). If you see dark smoke, the cat isn't working.

 

[stihl sawing]

Thanks Logbutcher, I'm gonna try that. This is only the second year but my stove is backpuffing bad. I can leave the dampner open and no back puffing. We have a round of snow coming tommorrow, After it goes away i'm going to let the fire go out and check to see if the cat needs cleaning.

 

[Wood Doctor]

Cat Disappeard in my Stove

Thanks Logbutcher, I'm gonna try that. This is only the second year but my stove is backpuffing bad. I can leave the dampner open and no back puffing. We have a round of snow coming tommorrow, After it goes away i'm going to let the fire go out and check to see if the cat needs cleaning.

My cat stove never back puffs. I simply clean off the steel plate I made with tap water every ten days. The $100 cat has now been dead for three years. Long live the death of the cat and good bye forever. I like red hot steel plates:

 

[logbutcher]

My cat stove never back puffs. I simply clean off the steel plate I made with tap water every ten days. The $100 cat has now been dead for three years. Long live the death of the cat and good bye forever. I like red hot steel plates:

Whiskey Tango Foxtrot Edward, what the H is that ? Interesting. You may make some $$$$ on that . Explain.

BTW: cats do work and do the job well. Look at vehicle catalytic combustors. When cat stoves first were made I was skeptical also. It averaged that the early cat stove ( 1989 VC Encore ) burnt ~ 1/3 less wood for the same BTUs and weather and space than the pre EPA VC Vigilant without a cat-- but NOT an EPA "non cat".

 

[3fordasho]

The honeycomb ceramic catalysts in our High Valley stove seem to plug with fly ash quite often. Do any of you use the new metal catalysts and do they resist plugging-up as advertised? I burn very dry wood, and don't engage the catalist until temp reads 600.

I run a pair of Fireviews- one for about 5 years, 2nd Fireview on it's 2nd season. Never had a problem with flyash plugging the cat ever. Both still have the ceramic cats. The fireview uses a flame protection plate right before the smoke/flame enters the cat. Basically a rectanular piece of stainless expanded metal. This will fill up with the flyash and gets cleaned about once or twice a season with a brush similar in shape to a toothbrush but with brass bristles instead of plastic. No stove disassembly required, just let it cool down. Perhaps something could be fabricated for your stove?

 

[Cerran]

Let's take a stab at this. But I gotta watch out for the lurker pros (humbolts:soldier waiting for the chance to virtual flame. Here goes:

We've used cat stoves since Vermont Castings introduced them as part of an engineered wood stove in 1989. Like the ones in your truck, they have a limited life.

The ceramic catalysts last for about 12,000 hours ( +/- 2 years of 24/7 hard use) before the paladium or platinum coating wears off and/or the ceramic starts to crack.

I put in a steel cat last winter for our normal 2-3 season replacement. Good so far with just the usual brush-off cleaning. The company, Sud Chemie, says that the metal cat will "light off" at lower temps ( ~ 400 F ) and take higher temps without breaking up like the ceramic cats, and lst longer. We'll see.

So if your cat is well over the 12,000 hour life, replace it. Another way is to do the recommended (Corning) " vinegar bath" to restore the cat . A PITA.

We have a cat and non-cat stoves for heating. The cat stove holds a longer fire, use less wood for the same BTUs, and allow the stove to be damped way down overnight. Butt: cats demand more care and maintenance. Non cat stoves like our Oslo don't allow the air to be very low or very high---a mommie approach for clean burning.

Long way of saying: it's time to replace the cat if it's been in for a few years and used hard. To check the cat operation, get the stove hot ( 600-700 F on top), damper in the cat, then let the temp go back up before lowering the primary air. Then run outside (clothes on). If you see dark smoke, the cat isn't working.

Actually it won't put out more BTU's per unit wood per se depending on the stove and design of course. It might be more efficient than some of the non-cat units you have tried.

 

[logbutcher]

Actually it won't put out more BTU's per unit wood per se depending on the stove and design of course. It might be more efficient than some of the non-cat units you have tried.

Damn boy, you are semantically and technically correct. Forgive.umpkin:

Efficient yes. We use one stove of each now: same space to heat. You are bright...and right.

P.S. Where's spellcheck ?

 

[Wood Doctor]

Whiskey Tango Foxtrot Edward, what the H is that ? Interesting. You may make some $$$$ on that . Explain.

BTW: cats do work and do the job well. Look at vehicle catalytic combustors. When cat stoves first were made I was skeptical also. It averaged that the early cat stove ( 1989 VC Encore ) burnt ~ 1/3 less wood for the same BTUs and weather and space than the pre EPA VC Vigilant without a cat-- but NOT an EPA "non cat".

Yeah, I thought about a patent application, but I'm sure the legal boys in Washington would say, "too easy, can't possibly work."

I built a square stove collar using angle iron to replace the one that burned out after 20 years. Then I dropped in the 1/4" thick steel square plate shown above after I drilled the holes and beveled them on my drill press. The center bolt allows easy lift out.

This plate sometimes reaches 1400 F in my stove, almost cherry red. It burns out everything the cat combustor used to do. To clean it, all I do is run it under tap water once every ten days. I imagine it will last forever.

I made another one with slightly smaller holes and more of them. It works just as well. I'm saving it for a backup.

 

[logbutcher]

Yeah, I thought about a patent application, but I'm sure the legal boys in Washington would say, "too easy, can't possibly work."

I built a square stove collar using angle iron to replace the one that burned out after 20 years. Then I dropped in the 1/4" thick steel square plate shown above after I drilled the holes and beveled them on my drill press. The center bolt allows easy lift out.

This plate sometimes reaches 1400 F in my stove, almost cherry red. It burns out everything the cat combustor used to do. To clean it, all I do is run it under tap water once every ten days. I imagine it will last forever.

I made another one with slightly smaller holes and more of them. It works just as well. I'm saving it for a backup.

NICE !!!

 

[Cerran]

I would imagine the biggest drawback will be the temperature it has to get up to to properly fully combust gasses. Remember CO doesn't start to fully oxidize until 1300 degrees unless in the presence of a catalyst. Also if you bank the stove down very low I'm betting the plate will not work where a catalyst will.

 

[Wood Doctor]

Cat vs. Plate

... Also if you bank the stove down very low I'm betting the plate will not work where a catalyst will.

Pray tell, what does a catalytic combustor really do at 600 F or less? I think practically nothing. At that temp, the cat is just acting as a throttling processor, slowing down the combustion speed and not doing much more than a flue damper.

The cat (and my plate) both do the same thing, trap and burn secondary flue gases before they reach the stove pipe, thus cleaning up the smoke. Burn time is also extended and efficiency increases. To operate well, both have to be hot, 1000 F or higher.

The biggest difference between my thick perforated steel plate and a cat is that my plate is easy to clean (the cat is not), my plate will last practically forever, (the cat will not), and my plate costs about $10.

 

[Cerran]

Pray tell, what does a catalytic combustor really do at 600 F or less? I think practically nothing. At that temp, the cat is just acting as a throttling processor, slowing down the combustion speed and not doing much more than a flue damper.

The cat (and my plate) both do the same thing, trap and burn secondary flue gases before they reach the stove pipe, thus cleaning up the smoke. Burn time is also extended and efficiency increases. To operate well, both have to be hot, 1000 F or higher.

The biggest difference between my thick perforated steel plate and a cat is that my plate is easy to clean (the cat is not), my plate will last practically forever, (the cat will not), and my plate costs about $10.

At around 600F The catalyst will burn off volatile gasses like CO which the steel plate will not. As the catalyst heats up you can continue to feed it cooler gasses and still get reasonably complete combustion.

In basic terms the Catalyst lowers the temperature at which the oxidation reaction takes place, the steel plate does not do this.

If you were to stick a combustion meter on your wood stove stack you would find that with the catalyst under most conditions there would be significantly less emissions, particularly CO and other hydrocarbons.

The catalyst does not act as a throttling processor as you claim it actually lowers the energy required to complete combustion.

A plate like yours would very likely cause serious problems on shorter chimneys with less draft.

 

[logbutcher]

Just a jump-in on catalytic combustors: it's the plating of very $$$$ metals such as paladium bonded to the substrate of ceramic (older substance) or the newer metal bonding that holds a high temperature. It is that that ( where's the grammar nazi) continues to burn off incompletely burnt gases in your stove and truck. Not sure whether or not CO can be "burnt off".

Now that metal plate is a damn bright idea. :star: Even if it can't have the same efficiency as a cat, it does a good part of the job. If the Doc were near I'd buy the man a drink. Unfortunately we've been snow dumped and the logger has to get into the woods.My back hurts. Whine for us....................:shame:

 

[Wood Doctor]

... A plate like yours would very likely cause serious problems on shorter chimneys with less draft...

Baloney. I already tested that with other stoves connected to shorter chimneys. It works there also. Sorry, Cerran, I believe you are firing from the hip. What proof do you have? I doubt seriously that you have ever replaced a cat combustor with a steel plate. I have and it works better than any expensive cat combustor that I messed around with for 20 years.

However, I have no intention of making these for resale or trying to make any money off of them whatsoever. I posted here to offer an altentive that I know works.

I rest my case.

 

[046]

thanks for the great idea!!

can't dispute what works .... may have to try this in my JUCA. which has nothing to slow down gases except damper.

been needing to install some type of trap for gases to finish burning before going up chimney. my stove already burns extremely hot, so burning at lower temps will not be an issue.

thinking of welding angle iron on each side to provide support, just below top of burn chamber. 1/4in thick plates can be butted into each other to create a tunable trap.

that way if it's doesn't work... I can easily yank it apart or add more plates to extend size of smoke trap.

I already tested that with other stoves connected to shorter chimneys. It works there also. Sorry, Cerran, I believe you are firing from the hip. What proof do you have? I doubt seriously that you have ever replaced a cat combustor with a steel plate. I have and it works better than any expensive cat combustor that I messed around with for 20 years.

I rest my case.

 

[Wood Doctor]

thanks for the great idea!!

can't dispute what works .... may have to try this in my JUCA. which has nothing to slow down gases except damper.

been needing to install some type of trap for gases to finish burning before going up chimney. my stove already burns extremely hot, so burning at lower temps will not be an issue.

thinking of welding angle iron on each side to provide support, just below top of burn chamber. 1/4in thick plates can be butted into each other to create a tunable trap.

that way if it's doesn't work... I can easily yank it apart or add more plates to extend size of smoke trap.

Something like this to support the plate?

I used angle iron and 5/16" bolts rather than weldings. After two years, this collar that supports the steel plate is still intact. I tried two stacked steel plates, separated slightly, but one works just as well and is much less hassle.

By now, I would already have spent over $200 on cat combustors that would have given up and been a PITA to clean.

 

[Ohiowoodguy]

Are you saying that a perferated steel plate is burning the exhaust gasses like a cat?

 

[cassandrasdaddy]

the cat in mine

is reading 1400-1500 right now

 

[Cerran]

Baloney. I already tested that with other stoves connected to shorter chimneys. It works there also. Sorry, Cerran, I believe you are firing from the hip. What proof do you have? I doubt seriously that you have ever replaced a cat combustor with a steel plate. I have and it works better than any expensive cat combustor that I messed around with for 20 years.

However, I have no intention of making these for resale or trying to make any money off of them whatsoever. I posted here to offer an altentive that I know works.

I rest my case.

You don't have a case, the fact is the steel plate does not do the same thing as a catalyst.

You may think it does, but if you were to do actual testing you would find it performs very differently and my educated guess is that much worse over a wider range of applications than a catalyst.

This doesn't even mention the fact that standard steel starts to Carbuerize at 800F

This is 12+ years of combustion engineering talking.

Note I'm not saying the steel plate isn't working, but I am saying that it doesn't do the same job at the catalyst.