Considering a cat stove

[moresnow]

So far it looks like the BK Princess is the best stove for my situation.
This stove is not my primary heat. When the Drolet is going the oil boiler rarely kicks on.
Most would not consider my setup to be ideal. But I do. It keeps the living room warm. Surrounding rooms are good as I have a small circulator fan in the upper corner of a door. But the bedrooms upstairs are a bit cool which is the way I like it.

The Princess has been pretty proven over the years. I would recommend you consider running it around the clock. The gentle metered heat from these BK's seems to work best if not being started and stopped/interrupted. At least for the one's I am around. Guessing your going to enjoy your extra free time away from stove tending. Should be able to get some jingle back out of the Drolet also. Have fun.

 

[Woody Stover]

Yes it is asking about cats

He's open to both, the way I read it.

Most would not consider my setup to be ideal.

Can you describe the layout further?
Yes, we're on one level but we keep the mud room/bedroom door open only 6" and the bedroom stays cooler, main room warmer.

I would recommend you consider running it around the clock. The gentle metered heat from these BK's seems to work best if not being started and stopped/interrupted. At least for the one's I am around. Guessing your going to enjoy your extra free time away from stove tending.

I run mine a bit higher around the clock if I need that amount of heat. Like it is right now, lows in the low 30s and highs low 40s, I might burn a night load but then cut the air in the morning and hold the coals a long time. I don't need the stove to do much heating in the afternoon. Even if the coals eventually go out, no biggie, the house doesn't vary more than a couple degrees. I might have to re-light the stove eventually since it's only 1.5 cu.ft. but it's easy when you're an expert and have streamlined the process.

 

[Woody Stover]

I had the princess, great stove but my house is too big for it so I switched to a progress hybrid and it's better for my 2800sf.

So much for the "fire box size=output" argument...they are about the same size, right?

You aren’t a fan of cat stoves, everyone knows that

Yeah, but he hasn't tried a Woodstock yet.

 

[BKVP]

Gentlemen,

There are three (current) ways to meet 2020 EPA standards.

1) Destroy particulates thermally. 1176F and higher will breakdown particulates. As the numerical part of the standard is lowered, the turn down rate of secondary combustion heaters also is subject to being decreased. The disadvantage of thermal destruction is that one or more components are being subjected to high temps. Tubes, baffles etc can and do need replacing depending on many variables.

2) Chemical conversion begins at 550F and typically involves the use of a combustor, treated with a catalyst. These combustors typically isolate excessive temperatures and focus them within a replaceable element. Yes, they do diminish in effectiveness over time, as do secondary combustion stove components. They can also fail when not properly maintained, again just like any wood stove. The turn down rate is not effected by the 2020 EPA numerical standard.

3) Hybrid heaters are not new. We made one in the 1980's. For us, they were more costly to manufacture and did not provide any reductions in particulates or gains in efficiency compared to straight chemical conversion designs. A possible advantage of hybrid designs is a slight amount of additional flame when burn rate is lowered. Again, manufacturers will design products to address needs of the consumers.

Contradicting that last sentence, please ALL OF YOU remember that ALL manufacturers are engineering products to pass a test and at the same time.....hopefully address the burn characteristics that wood burners prefer.

The problem with regulation is that is can result in inferior combustion designs if rushed to market. This round of EPA standards began review in November 2009. I know, I was there.

If you are considering buying a wood heater that uses a combustor, the number 1 question to ask is..What element in design has been employed to prevent the combustor from repeatedly reaching 1600F under adverse (excessive) stack effect.

As for consideration of secondary combustion stoves, go with consumer reviews. It would be too difficult to evaluate threshold temperatures and their effects on the essential elements needed for continued, clean combustion.

In closing, because I have to pack for Boston, you ladies and gentlemen do a superb job at education..and a little debating too.

As a group, let all of us encourage wood stove users to buy a flashlight and keep it next to their moisture meter. At the end or beginning of each burn season, conduct a very thorough inspection of their stoves. Look for combustors that are degrading or plugging, look for crack in tubes or baffles and in doing so provide continued assurance that their wood heaters will burn clean and efficiently.

Adios!

 

[begreen]

There are three (current) ways to meet 2020 EPA standards.

1) Destroy particulates thermally. 1176F and higher will breakdown particulates. As the numerical part of the standard is lowered, the turn down rate of secondary combustion heaters also is subject to being decreased. The disadvantage of thermal destruction is that one or more components are being subjected to high temps. Tubes, baffles etc can and do need replacing depending on many variables.

Reaching that temp quickly in an insulated firebox is easy with dry wood and kindling. It can be done in 10-15 minutes with a top down start. All wood stoves are subjected to high temps. Modern EPA stoves typically have stainless steel tubes or baffle/secondary box. Unless the stove is frequently run at overfiring temperature failure of these components is not common. Unlike combustors, they do not degrade with time. They usually reach point of failure at which time the failed part should be replaced. This is not frequent with a properly designed and run stove.

2) Chemical conversion begins at 550F and typically involves the use of a combustor, treated with a catalyst. These combustors typically isolate excessive temperatures and focus them within a replaceable element. Yes, they do diminish in effectiveness over time, as do secondary combustion stove components. They can also fail when not properly maintained, again just like any wood stove. The turn down rate is not affected by the 2020 EPA numerical standard.

Combustors typically run in the 1100-1500º range. Depending on the stove design there are numerous points that get very hot and are prone to failure due to operating a continuous high temps. These parts may be bypass mechanisms and/or expensive refractory packages in addition to an expensive cat replacement on a regular basis. Catalysts are more vulnerable to failure due to real world conditions of contamination, temperature shock, too aggressive cleaning, failure to close the bypass, etc.. They are excellent at what they do, but there is is greater latitude for operator error causing issue.

3) Hybrid heaters are not new. We made one in the 1980's. For us, they were more costly to manufacture and did not provide any reductions in particulates or gains in efficiency compared to straight chemical conversion designs. A possible advantage of hybrid designs is a slight amount of additional flame when burn rate is lowered. Again, manufacturers will design products to address needs of the consumers...

...If you are considering buying a wood heater that uses a combustor, the number 1 question to ask is..What element in design has been employed to prevent the combustor from repeatedly reaching 1600F under adverse (excessive) stack effect.

Excessive draft is a common problem for all wood heaters. It's something that needs to be recognized in the field by the stove seller and installer. Very frequently it is not. Ideally stove sellers and installers would have much better training about the stack effect, but unfortunately making a sale is more important for some than having a safe and satisfied customer. Also ideally would be options available to the trained installer for adjusting the stove in situations of high draft, but that would need testing expensive field test equipment and time to be sure that the stove's emissions were not compromised. Though perhaps it could be as simple as a factory manufactured part that restricts air supply under lab tested conditions of high draft, similar to what Regency came up with. This is a real world problem that may lead some mfgs. to automated systems that can be lab tested and certified under a variety of stack conditions and not just with a fixed 15' flue.

 

[webby3650]

similar to what Regency came up with.

What technology did regency develop?

 

[begreen]

On the i2600 there is a restrictor plate. And it sounds like Osburn is experimenting with secondary tube restriction via washers in another thread. Not sure if either are an ideal solution, but they do indicated the factory acknowledging an issue with high draft installs.

 

[webby3650]

On the i2600 there is a restrictor plate

After all the reported failures and poor burn times I’m glad they are making revisions.

 

[begreen]

After all the reported failures and poor burn times I’m glad they are making revisions.

They came out with a remedy by the next season IIRC. Maybe 6-9 months?

 

[BKVP]

Reaching that temp quickly in an insulated firebox is easy with dry wood and kindling. It can be done in 10-15 minutes with a top down start. All wood stoves are subjected to high temps. Modern EPA stoves typically have stainless steel tubes or baffle/secondary box. Unless the stove is frequently run at overfiring temperature failure of these components is not common. Unlike combustors, they do not degrade with time. They usually reach point of failure at which time the failed part should be replaced. This is not frequent with a properly designed and run stove.

Unfortunately that is not true across all wood stoves using tubes. The thickness, type of metal and threshold temps cause failure. There was a study done of "intact secondary combustion" stoves and most exceeded by a significant margin their original emissions grades.

Combustors typically run in the 1100-1500º range. Depending on the stove design there are numerous points that get very hot and are prone to failure due to operating a continuous high temps. These parts may be bypass mechanisms and/or expensive refractory packages in addition to an expensive cat replacement on a regular basis. Catalysts are more vulnerable to failure due to real world conditions of contamination, temperature shock, too aggressive cleaning, failure to close the bypass, etc.. They are excellent at what they do, but there is is greater latitude for operator error causing issue.

Sorry again, but even technical staff at one of the biggest secondary combustion stove companies has posted on the web problems inherent in the design of baffles and how they can fail....will fail with time. Baffle plates, tubes and cerablankets are very costly...more than combustors.

Excessive draft is a common problem for all wood heaters. It's something that needs to be recognized in the field by the stove seller and installer. Very frequently it is not. Ideally stove sellers and installers would have much better training about the stack effect, but unfortunately making a sale is more important for some than having a safe and satisfied customer.
Agreed!

Also ideally would be options available to the trained installer for adjusting the stove in situations of high draft, but that would need testing expensive field test equipment and time to be sure that the stove's emissions were not compromised. Though perhaps it could be as simple as a factory manufactured part that restricts air supply under lab tested conditions of high draft, similar to what Regency came up with. This is a real world problem that may lead some mfgs. to automated systems that can be lab tested and certified under a variety of stack conditions and not just with a fixed 15' flue.

As emissions are reduced, some stoves become more efficient. Great until draft requirements are compromised and then all sorts of problems can occur.

 

[BKVP]

Unfortunately that is not true across all wood stoves using tubes. The thickness, type of metal and threshold temps cause failure. There was a study done of "intact secondary combustion" stoves and most exceeded by a significant margin their original emissions grades.

Sorry again, but even technical staff at one of the biggest secondary combustion stove companies has posted on the web problems inherent in the design of baffles and how they can fail....will fail with time. Baffle plates, tubes and cerablankets are very costly...more than combustors.

 

[bholler]

Unfortunately that is not true across all wood stoves using tubes. The thickness, type of metal and threshold temps cause failure. There was a study done of "intact secondary combustion" stoves and most exceeded by a significant margin their original emissions grades.

Sorry again, but even technical staff at one of the biggest secondary combustion stove companies has posted on the web problems inherent in the design of baffles and how they can fail....will fail with time. Baffle plates, tubes and cerablankets are very costly...more than combustors.

I am not sure why you think those things cost more than combusters. Yes if you had to do them all every couple years like a combusters then yes I would agree. But tubes which are the most expensive thing there rarely need replaced. Most baffles are in the 100 to 150 range and can easily last 10 years or more. We typically charge $10 to cut a new blanket. And those typically last pretty long unless they need pulled to clean every year.

 

[BKVP]

I am not sure why you think those things cost more than combusters. Yes if you had to do them all every couple years like a combusters then yes I would agree. But tubes which are the most expensive thing there rarely need replaced. Most baffles are in the 100 to 150 range and can easily last 10 years or more. We typically charge $10 to cut a new blanket. And those typically last pretty long unless they need pulled to clean every year.

I just reviewed baffles, tubes and refractory components for an EPA rule making. My data is accurate because it came from manufacturer pricing. And as for frequency of needed replacement, that varies. Some stainless tubes, made of 18 gauge, according to real world use, require replacement every 8-10 years. Of course, like every single application, actual longevity varies based upon many factors.

 

[webby3650]

I am not sure why you think those things cost more than combusters. Yes if you had to do them all every couple years like a combusters then yes I would agree. But tubes which are the most expensive thing there rarely need replaced. Most baffles are in the 100 to 150 range and can easily last 10 years or more. We typically charge $10 to cut a new blanket. And those typically last pretty long unless they need pulled to clean every year.

You are correct, it’s not very often that all baffle components need replaced at the same time. But when they do very few customers are willing to take it on. The cost of the parts plus labor is definitely more expensive than a cat. Most customers will change a cat with a little instruction. Unless it’s an older VC of course.

 

[bholler]

I just reviewed baffles, tubes and refractory components for an EPA rule making. My data is accurate because it came from manufacturer pricing. And as for frequency of needed replacement, that varies. Some stainless tubes, made of 18 gauge, according to real world use, require replacement every 8-10 years. Of course, like every single application, actual longevity varies based upon many factors.

Ok well I work on allot of stoves. And I honestly have only replaced 2 sets of tubes. I have seen a few others that were bad but the stove was burnt out so they weren't worth replacing. Yes if someone beats up their baffle and breaks it often it could easily cost as much as cats but if you just pay attention they should easily last 10 years. Yes the blanket will need replaced every few years if it is pulled for yearly cleanings but if bought in bulk it is pretty cheap.

 

[bholler]

You are correct, it’s not very often that all baffle components need replaced at the same time. But when they do very few customers are willing to take it on. The cost of the parts plus labor is definitely more expensive than a cat. Most customers will change a cat with a little instruction. Unless it’s an older VC of course.

Most tube stoves can easily be serviced by customers given the same amount of instruction. There are a few that are a pita but most are pretty easy

 

[begreen]

Unfortunately that is not true across all wood stoves using tubes. The thickness, type of metal and threshold temps cause failure. There was a study done of "intact secondary combustion" stoves and most exceeded by a significant margin their original emissions grades.

Was this the 20 yr old 1998 Oregon study? IIRC several of those stoves were poorly maintained. And the cost of bringing them back to good operating condition would vary with the degree of abuse and neglect. Still, replacing a few tubes and firebrick can be less than the regular replacement of a cat on some stoves and less frequent.

 

[ColdNorCal]

SBI Century tubes are $50 each. The baffle is $70. These are prices from SBI, could possibly find them discounted else where, and all can easily be replaced per the manual. SBI has the tubes figured out. Simply give them a turn to unlock/release and slide them out. No nuts, screws, pins... I never measured the thickness of the tubes but they feel substantial and are a lot thicker then 18 gauge.

 

[BKVP]

Was this the 20 yr old 1998 Oregon study? IIRC several of those stoves were poorly maintained. And the cost of bringing them back to good operating condition would vary with the degree of abuse and neglect. Still, replacing a few tubes and firebrick can be less than the regular replacement of a cat on some stoves and less frequent.

“Some Stoves” is precisely the point, thank you BeGreen. We cannot lump all Stoves into the same pot based upon technology...thank you.

 

[bholler]

“Some Stoves” is precisely the point, thank you BeGreen. We cannot lump all Stoves into the same pot based upon technology...thank you.

Can you tell us what tube stoves typically cost more to maintain than cat stoves? Because the ones I typically work on simply do not unless they are abused.

 

[begreen]

“Some Stoves” is precisely the point, thank you BeGreen. We cannot lump all Stoves into the same pot based upon technology...thank you.

For sure. The cost of maintenance on a refractory package stove can be much higher than on a more conventional design. Likewise there are non-cat stoves without tubes. And a stove run at its upper limit of performance is likely to wear faster than one run at say 75% of its maximum potential.

 

[Woody Stover]

Was this the 20 yr old 1998 Oregon study?

Well, he didn't say "no."

even technical staff at one of the biggest secondary combustion stove companies has posted on the web problems inherent in the design of baffles and how they can fail....will fail with time.

Can you link that material? Thanks.

We cannot lump all Stoves into the same pot based upon technology

Right. I don't know for sure but I assume a cheap secondary stove is going to have thinner metal in the tubes or secondary box, and cheaper baffle material.
Or you could have a cat stove built with thin steel...will it rust through in 10-20 years? If you've paid a $3K for the stove, that's gonna end up costing you $150-300 a year...

 

[BKVP]

Can you tell us what tube stoves typically cost more to maintain than cat stoves? Because the ones I typically work on simply do not unless they are abused.

There is more than one and it’s unprofessional to name them. So I won’t. But according to the companies price sheets, there are 4 tubes and retail price is $80 per tube. Another example is a baffle plate for a top seller, $316.00 for the kit. There are dozens more.

The point I was making is what I posted earlier....not all cat Stoves are alike....not all non cats are alike with regard to quality, durability and the ability to maintain clean burning.

 

[BKVP]

For sure. The cost of maintenance on a refractory package stove can be much higher than on a more conventional design. Likewise there are non-cat stoves without tubes. And a stove run at its upper limit of performance is likely to wear faster than one run at say 75% of its maximum potential.

We are in agreement.....

 

[BKVP]

Well, he didn't say "no."
Can you link that material? Thanks.
Right. I don't know for sure but I assume a cheap secondary stove is going to have thinner metal in the tubes or secondary box, and cheaper baffle material.
Or you could have a cat stove built with thin steel...will it rust through in 10-20 years? If you've paid a $3K for the stove, that's gonna end up costing you $150-300 a year...

The studies (2) identify the manufacturer and models. I will not link those.

You should read some studies written by lab experts on combustion and related emissions studies. When a sweep tosses a ceramic blanket (and two weeks ago I confirmed in person at multiple locations this transpires) the emissions profiles suffer. Of course great, professional sweeps would never remove and not replace the blanket. Experts provide testimony to how if a tube has a small crack, what effect that has, let alone a cracked baffle or misfitting essential element to clean combustion.

Again, the point is there are cat stoves that can have the same issues.

As my first post said clear as day (except today because of all the snow), all wood Stoves need regular inspection and maintenance. If you care to keep a stove as clean burning as possible, that has to be part of the education.