Time for cat #5!

[BKVP]

With cat inflation also comes wood inflation. Can’t really guess whether either item will change. Cats have remained very steady.

The big “leap” is the 20% wood savings which is what I measured as have many other full time wood heaters but that’s variable. Wood usage efficiency over a winter is not equivalent to the steady state efficiency rating the epa gives a stove.

I understand that this is academic and just for fun.

The entire issue of efficiency is getting very interesting. EPA only posts what comes about in the M28R or prior ASTM3053 testing.

The Environment Canada study, EPA new study on VOC's and NESCAUM studies are all using different methods, yet the efficiency ratings are fairly equal for the same models of stoves going through different methods in different labs.

The current methods used by EPA do not show as large a difference between technologies, but the new studies do. That is why your observations regarding wood savings are not just yours, but many other, supported by these studies.

I want to reiterate, the studies being done are not about PM data. They are focusing great attention on VOC's! The two challenges I see going forward are going to be an exceedance metric during the entire duration of a test run and somehow VOC's will start to be regulated. It may be a few years for VOC's, but agencies are already calculating estimated tons being emitted and potential reductions based upon improved technologies.

BKVP

 

[Ashful]

This is assuming his cat life interval would be the same as yours, correct?

BKVP

No one has the same cat life interval as highbeam!

I'm starting season 6 with each of mine, now. They were running just fine at the end of season 5. I can't even imagine how I'd kill one in two years, but we are burning different wood, and have different usage profiles.

I did buy two new combustors, and will probably swap them out when I do my annual cleaning. That usually happens the weekend following my first fire each October.

 

[begreen]

Our average cat life is 15-18 years. Sure do miss them when they're gone.

 

[weee123]

No one has the same cat life interval as highbeam!

I'm starting season 6 with each of mine, now. They were running just fine at the end of season 5. I can't even imagine how I'd kill one in two years, but we are burning different wood, and have different usage profiles.

I did buy two new combustors, and will probably swap them out when I do my annual cleaning. That usually happens the weekend following my first fire each October.

Highbeam burns doug fir right? Maybe because of sap content in the fir it burns sootier than say, the hardwoods we burn on the east coast which would probably work the cat harder and kill it faster.

 

[Hoytman]

Loggers cord is just a local thing here where they bring 8’ logs. They still measure a cord as 4x4x8 but expect to lose 15-20% after processing.

Eight foot (8ft) logs how big around?

 

[Hoytman]

Will be interesting to see the full study. Quite honestly the Fisher numbers are as impressive is the BK all things considered.

 

[Highbeam]

That was just rounding. Midwest Hearth sells the cat for $239 + tax, so more like $260 each and probably higher in the future or at least $1300 for the next 5 cats?

As to BKVP's point, we have to be careful mixing my situation for the last decade and yours. A cat can be expected to last for 12000 hours so for you, 5 cats would last at least twice as many years since you burn about half as much. So 22 years?

I seem to be moving in your direction on wood consumption since here we are partway through October and I have yet to have more than a test burn. My little heat pump is doing a great job at reducing wood usage and cat usage.

 

[Highbeam]

No one has the same cat life interval as highbeam!

Come on now, only a fool reports cat life in years. We all know that these things have hours of use as their rating and my 9 month long heating season is why I can rack up the hours in so few years. If you venture away from this site especially you will find the more common life expectation for somebody burning full time with wood and observing their chimney to be quite a bit shorter than yours. Honestly, there are folks that simply don't care and never replace their cats.

As I wrote in the original post, don't waste wood on a dead cat trying to prove some sort of macho point. When it's dead it's dead.

My super long burn season at low settings burning softwood has got to be a factor in only getting the expected 12000 hours of cat life. If you're burning with a flame then the cat is getting an easy ride as the flame is doing some of the work, maybe even most of the work.

I don't swap the cat out until it dies but the point I want to make is that when it dies, get it replaced quick! There are no bonus points for smoking out the neighborhood, shorter burn times, and wasted fuel. It's actually cheaper to keep a functional cat in there.

 

[Highbeam]

Highbeam burns doug fir right? Maybe because of sap content in the fir it burns sootier than say, the hardwoods we burn on the east coast which would probably work the cat harder and kill it faster.

More important that the type of wood I think is that you eastern folks get shorter and colder winters so you burn at a higher thermostat setting, maybe even with some flames that help ease the burden on the catalyst.

 

[BKVP]

Highbeam burns doug fir right? Maybe because of sap content in the fir it burns sootier than say, the hardwoods we burn on the east coast which would probably work the cat harder and kill it faster.

I burn softwoods as well, my cats don't live as long as BeGreens, but vastly longer than Highbeams....

 

[Ashful]

Come on now, only a fool reports cat life in years. We all know that these things have hours of use

Fair enough. I'd guess my utilization is around 4500 hours per year on the main stove, running two loads per day. The second stove is probably more like 3500 hours per year, one load per day. So, five years = 23,000 hours on the main stove.

 

[Ashful]

Highbeam burns doug fir right? Maybe because of sap content in the fir it burns sootier than say, the hardwoods we burn on the east coast which would probably work the cat harder and kill it faster.

His wood may be killing the cat faster, but even more, I think it's more apt to reveal a failing cat. Highbeam is burning at a lower temperature, leaning hard on that catalyst to keep reburn going at low temperature. I wonder where his needle runs, most of the burn.

Conversely, I'm burning hardwoods, and at twice the rate, so nearly triple the BTU output. I'd bet my average combustor temperature is much higher, making me less reliant on having a good wash coat. It's very likely that a combustor that's failing to perform for Highbeam, might be found perfectly acceptable for my usage profile. I don't know, but maybe we should try that someday.

Can a BK achieve non-catalytic reburn at 1100F, just like a non-cat? At that point, those running hot enough wouldn't even know if their combustor is working due to a catalyst, or just pure mechanics.

 

[BKVP]

His wood may be killing the cat faster, but even more, I think it's more apt to reveal a failing cat. Highbeam is burning at a lower temperature, leaning hard on that catalyst to keep reburn going at low temperature. I wonder where his needle runs, most of the burn.

Conversely, I'm burning hardwoods, and at twice the rate, so nearly triple the BTU output. I'd bet my average combustor temperature is much higher, making me less reliant on having a good wash coat. It's very likely that a combustor that's failing to perform for Highbeam, might be found perfectly acceptable for my usage profile. I don't know, but maybe we should try that someday.

Can a BK achieve non-catalytic reburn at 1100F, just like a non-cat? At that point, those running hot enough wouldn't even know if their combustor is working due to a catalyst, or just pure mechanics.

Catalyst conversion begins at 550F. The recent studies I referenced show that. When ADEC in Alaska tried electric static precipitators, they show no reduction in PM. By the time the ESP was functional, so was the cat, around 18 minutes.

BKVP

 

[ABMax24]

No need for guessing and there is still much more to this most recent study, just under limited release. Full study can be posted soon, once deemed "sharable".

Environment Canada just paid to have a VERY extensive study done on efficiencies, VOC's, black carbon etc. It is based upon an Italian cordwood test method. The finding are very interesting, especially given the regulators are really looking at VOC's. But this is a snip on the 93 tests they did as it relates to efficiency. (We can start a new thread once the entire study can be posted)

I'm certainly interested in reading that study, although maybe our government should invest more in wildfire fighting to limit PAH and VOC emissions?

Anyway, that table sure makes the pieces fit, I could never figure out why my math on natural gas saved and wood consumed didn't properly line up. Should have know better than trust SBI's overly optimistic efficiency numbers. I regularly question why I bought this stove instead of buying the BK I wanted, this data doesn't make that feeling of regret any better.

 

[BKVP]

Will be interesting to see the full study. Quite honestly the Fisher numbers are as impressive is the BK all things considered.

I agree. But Alaska already has a "1st hour filter pull exceedance metric and only 7-8 stoves remain on the list. The real, very serious issue is some state and regional programs ONLY permits stoves on that list.

Once they move to VOC's, the real challenge transpires!

BKVP

 

[BKVP]

I agree. But Alaska already has a "1st hour filter pull exceedance metric and only 7-8 stoves remain on the list. The real, very serious issue is some state and regional programs ONLY permits stoves on that list.

Once they move to VOC's, the real challenge transpires!

BKVP

That is not why it was posted, to make you feel bad, sorry. But as many here acknowledge, marketing numbers may be a stretch. Also KEEP IN MIND, those were low burn rate efficiency values. A secondary combustion stove like your will fair better in high burns. Of course data shows few folks run on high very often.

There were great classes I attended. A head fire (wind blowing in direction of field being burned) burned cleaner that a tail fire (wind not blowing flames towards field being burned) showed huge differences. The head wind burned much cleaner.

I argued that both catalytic and secondary emissions (both PM and VOC's) were much, much lower in 2020 EPA stoves than the conventional wood stoves tested. There are estimated 6 million of those still in use. Take the 6 million and multiply that by the 30+ gr/h reduction over both current technologies, and forget about ratcheting down on current stoves. I hope it did not fall on deaf ears!

Your SBI is a great stove. Have no regrets. Great products from a great company.

BKVP

 

[ABMax24]

That is not why it was posted, to make you feel bad, sorry. But as many here acknowledge, marketing numbers may be a stretch. Also KEEP IN MIND, those were low burn rate efficiency values. A secondary combustion stove like your will fair better in high burns. Of course data shows few folks run on high very often.

There were great classes I attended. A head fire (wind blowing in direction of field being burned) burned cleaner that a tail fire (wind not blowing flames towards field being burned) showed huge differences. The head wind burned much cleaner.

I argued that both catalytic and secondary emissions (both PM and VOC's) were much, much lower in 2020 EPA stoves than the conventional wood stoves tested. There are estimated 6 million of those still in use. Take the 6 million and multiply that by the 30+ gr/h reduction over both current technologies, and forget about ratcheting down on current stoves. I hope it did not fall on deaf ears!

Your SBI is a great stove. Have no regrets. Great products from a great company.

BKVP

No apology needed, your data just confirmed what I was already inferring from first hand empirical information. I guess mine is the 2015 model, and possibly fares a bit better in efficiency with less secondary air and no stainless sheet under the stove top.

No doubt SBI builds a great stove, and has good customer service.

Anyway, back to the regularly scheduled program.

 

[Highbeam]

His wood may be killing the cat faster, but even more, I think it's more apt to reveal a failing cat. Highbeam is burning at a lower temperature, leaning hard on that catalyst to keep reburn going at low temperature. I wonder where his needle runs, most of the burn.

Conversely, I'm burning hardwoods, and at twice the rate, so nearly triple the BTU output. I'd bet my average combustor temperature is much higher, making me less reliant on having a good wash coat. It's very likely that a combustor that's failing to perform for Highbeam, might be found perfectly acceptable for my usage profile. I don't know, but maybe we should try that someday.

Can a BK achieve non-catalytic reburn at 1100F, just like a non-cat? At that point, those running hot enough wouldn't even know if their combustor is working due to a catalyst, or just pure mechanics.

My cat meter runs near the top of the range when the stat is on low and the firebox black. The cat is working extra hard. Then, when it fails, since it was the only thing doing any work, the failure is dramatically evident. I’m still getting the expected lifespan of the catalyst so I’m happy. So long as your chimney is not smoking then I’d say keep running the old cat as it’s effective enough.

 

[Todd]

Eight foot (8ft) logs how big around?

8-14” diameter

 

[Ashful]

My cat meter runs near the top of the range when the stat is on low and the firebox black. The cat is working extra hard. Then, when it fails, since it was the only thing doing any work, the failure is dramatically evident. I’m still getting the expected lifespan of the catalyst so I’m happy. So long as your chimney is not smoking then I’d say keep running the old cat as it’s effective enough.

I'll be honest and say I don't really know if my chimney is making smoke. There are little whiffs of something coming out, probably steam. But I don't waste my day sitting and looking at it, either. It's also dark outside when I do most of my loading, which is the time I'd be inclined to look... if it weren't dark.

 

[BKVP]

My cat meter runs near the top of the range when the stat is on low and the firebox black. The cat is working extra hard. Then, when it fails, since it was the only thing doing any work, the failure is dramatically evident. I’m still getting the expected lifespan of the catalyst so I’m happy. So long as your chimney is not smoking then I’d say keep running the old cat as it’s effective enough.

Highbeam is correct! Due to increased residence time, the combustor is usually hotter than when running on high.

BKVP

 

[Todd]

So what about hybrid stoves? Will the cat last longer since it’s getting some help? Maybe that’s why Jotul has a 20 year cat warranty for the F500.

 

[BKVP]

Read all warranties carefully. Some stipulate "against mfg defect". In my 27 years, I have never seen a mfg defect in ceramic combustors. However, I have seen a couple metal substrates fail structurally if brazed sections release. This usually happens when it get excessively hot. Then it's not a mfg defect. See what just happened.

BKVP

 

[Ashful]

Highbeam is correct! Due to increased residence time, the combustor is usually hotter than when running on high.

BKVP

Good point. So what's your personal theory on why Highbeam rips thru combustors every 12000 hours, whereas you and I are doing easily more double that, without issues?

Smoke or steam aside, he says there's goo running down the outside his chimney if he pushes it much past that 12k mark. I just checked my chimney screen, uncleaned since last year and protected from rain with a very large flagstone topper, and it's perfectly clean after a full season of burning. Zero build-up on a 5/8" mesh, with a 5 year old cat at somewhere around 18k hours on that particular unit.

 

[BKVP]

Good point. So what's your personal theory on why Highbeam rips thru combustors every 12000 hours, whereas you and I are doing easily more double that, without issues?

Smoke or steam aside, he claims there's goo running down his chimney if he pushes it much past that 12k mark. I just checked my chimney screen, uncleaned since last year and protected from rain with a very large flagstone topper, and it's perfectly clean after a full season of burning. Zero build-up on a 5/8" mesh.

I have wondered that for several years. To be honest, it's not reflective of 99% of BK owners. But his observations are his and his sharing keeps me exploring ideas for improvement. We don't just buy cats, we pursue better performance.

Just since last week's conference and the studies being done, focusing on methane conversion is top of the list.

BKVP