Time for cat #5!

[weee123]

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.

I’m a weirdo and like to make sure I’m burning as clean as possible and will go out with a flashlight to check on the chimney lol

 

[Highbeam]

I’m a weirdo and like to make sure I’m burning as clean as possible and will go out with a flashlight to check on the chimney lol

Me too. I like seeing just the heat waves.

 

[Highbeam]

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.

The good hybrids from folks like Woodstock are no different. Those folks also get the 10-12k hours of expected life if they’re paying attention.

 

[Highbeam]

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.

It’s best to accept the fact that cat life is variable. Lots of factors have an effect on life expectancy. Also don’t discount the frog in water illusion where you long cat life folks just don’t realize how bad it had gotten. Especially when you’re not checking for chimney smoke.

My point is change it when it’s ready. I am more than happy for someone that gets longer cat life than the rated 12k. Keep an eye on your stack.

 

[Ashful]

It’s best to accept the fact that cat life is variable. Lots of factors have an effect on life expectancy. Also don’t discount the frog in water illusion where you long cat life folks just don’t realize how bad it had gotten. Especially when you’re not checking for chimney smoke.

My point is change it when it’s ready. I am more than happy for someone that gets longer cat life than the rated 12k. Keep an eye on your stack.

I agree, there's definitely a frog in the water scenario, not denying that. I always note the super-active nature of a new cat, by comparison to the one it's replacing.

To be honest, I hate and dread running new cats, and watching the needle peg into nuclear territory. Much happier when they're a year old, and running comfortably at 12 o'clock all day long.

I would cling to us burning different wood types, as the full explanation of why you see goo dripping down the outside of your chimney at 12,000 hours, and I can go double that without even a hint of build-up on my chimney cap screen. However, I think BKVP has historically mostly burned the same wood as you, which if true, would kill my theory.

And I accept that cat life is variable. Don't mistake my questioning as anything more than idle curiosity.

 

[ABMax24]

I wonder if there is a compound in your wood that is poisoning the catalyst? Sulphur, Phosphorus, etc. Or at least in higher than expected concentrations that cause faster deterioration? Or a compound that due to the low burn rate poisons the catalyst, but wouldn't in a stove operated at higher temperatures because said poison would be burnt off?

 

[BKVP]

I agree, there's definitely a frog in the water scenario, not denying that. I always note the super-active nature of a new cat, by comparison to the one it's replacing.

To be honest, I hate and dread running new cats, and watching the needle peg into nuclear territory. Much happier when they're a year old, and running comfortably at 12 o'clock all day long.

I would cling to us burning different wood types, as the full explanation of why you see goo dripping down the outside of your chimney at 12,000 hours, and I can go double that without even a hint of build-up on my chimney cap screen. However, I think BKVP has historically mostly burned the same wood as you, which if true, would kill my theory.

And I accept that cat life is variable. Don't mistake my questioning as anything more than idle curiosity.

Your theory is toast because I do burn Douglas Fir, Western Larch, Black Pine and occasionally, NIELS.

BKVP

 

[Ashful]

Your theory is toast because I do burn Douglas Fir, Western Larch, Black Pine and occasionally, NIELS.

BKVP

Yep. Exactly my point:

I would cling to us burning different wood types... However, I think BKVP has historically mostly burned the same wood as you, which if true, would kill my theory.

Someday we'll have a good explanation for this. You and Highbeam should be seeing similar cat life, but I think you're putting what... 2x - 3x more hours on yours, than he can get out of his?

 

[BKVP]

Yep. Exactly my point:

Someday we'll have a good explanation for this. You and Highbeam should be seeing similar cat life, but I think you're putting what... 2x - 3x more hours on yours, than he can get out of his?

True.

 

[Highbeam]

Different installs, different stoves, different climates, different results.

The question isn’t why my cat life is short because I’m getting the expected rated cat life. The question is why are you two letting yours go so long? Does there have to ge a question or riddle to solve? Cat life varies with usage just like engines in your car.

 

[begreen]

Yep. Exactly my point:

Someday we'll have a good explanation for this. You and Highbeam should be seeing similar cat life, but I think you're putting what... 2x - 3x more hours on yours, than he can get out of his?

Someone may be bumping up the primary system thermostat when VP is away?

 

[BKVP]

Someone may be bumping up the primary system thermostat when VP is away?

The primary system is the KE40.

BKVP

 

[Hoytman]

I’m pretty sure he meant your wife could be turning up the KE40 when you leave home.

I’m also sure you realized what he meant with your reply.😂👍

 

[Highbeam]

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

Been thinking about this. I would say that the 12000 hours, or 20 burning months IS reflective of the majority of cat stove owners. I believe you’re continuing to focus on the ridiculous “years” metric and I am an outlier in that I burn more hours per year than most.

A quick look at real forum members posting their experiences shows the majority are swapping cats closer to 12000 than to whatever you are getting. Other wood forum members also burn more hours per year than the average.

You are a member of that other forum as well. Look at the data objectively. Think hours, not years. It is obvious to me that I’m not a 1%er.

 

[Ashful]

Been thinking about this. I would say that the 12000 hours, or 20 burning months IS reflective of the majority of cat stove owners. I believe you’re continuing to focus on the ridiculous “years” metric and I am an outlier in that I burn more hours per year than most.

We may say "years", because it's an easier count. But I already posted that I'm around 22,500 hours on one of my combustors, and there's no black goo running down my chimney, or even building up on my chimney cap screen.

That's what makes it interesting to me, that you see such a dramatic changeover from completely fine to goo running down the chimney, like a light going off at 12,000 hours. At least that's how you've described it in past threads. I've just never seen anything like it. My observation is more of the frog in boiling water, any reduction in performance is always so gradual and so slight as to be difficult to detect without swapping cats.

 

[Ashful]

Fired up today, beginning of season #6. Didn't clean chimney or combustor from season #5 yet, will get to that this weekend, but all is working well.

Someone had asked if I have smoke after closing bypass, so I went out and took a photo after doing it today, a rare daylight reload. Looks totally clear, just a hint of steam. This is 5 minutes after closing bypass, 20 minutes after lighting a cold load of five medium red oak splits, roughly 50% firebox capacity.

Roughly 17,500 hours on this combustor, so far. Thinking of leaving it another season or two.

 

[Highbeam]

If it works, no smoke, keep running it.

My cats don’t shut off at 12,000 hours but that’s the average with some deviation, especially that steel cat.

Funny how cold your cat runs. I have the meter with numbers and it stays much higher at lower thermostat settings. Right up until it wears out.

 

[Ashful]

Funny how cold your cat runs. I have the meter with numbers and it stays much higher at lower thermostat settings. Right up until it wears out.

Cold? That's actually above where mine settle, for most of the burn. Maybe this has something to do with the hours lifetime discrepancy?

Nothing special about my stoves, and that one was dialed down to the setting that gets me 24 hours on a full load, so a relatively low burn. If you're seeing hotter, then it points toward wood species being the primary difference, as we had suspected back at the beginning of this conversation.

 

[Highbeam]

Cold? That's actually above where mine settle, for most of the burn. Maybe this has something to do with the hours lifetime discrepancy?

Nothing special about my stoves, and that one was dialed down to the setting that gets me 24 hours on a full load, so a relatively low burn. If you're seeing hotter, then it points toward wood species being the primary difference, as we had suspected back at the beginning of this conversation.

I think you're right. At least it's the best most plausible explanation to date. Burning very dry softwoods at low output appears likely to mean my cat is doing a lot more work than a stove burning hardwoods at higher output rates. This harder life is indicated by much higher cat temperature and much shorter (though still within the rated expectation) catalyst life. Also telling is that when the cat fails it fails hard and fast because that dang cat was doing everything. A cold burning, air starved, smoldering pile of dry softwood makes some nasty tar filled smoke.

 

[Ashful]

Also, it makes sense that a catalyst would be either depleted or flattened more quickly at a higher temperature, than at a cooler temperature.

 

[Highbeam]

Also, it makes sense that a catalyst would be either depleted or flattened more quickly at a higher temperature, than at a cooler temperature.

I found the perfect analogy. LED Light bulbs. The manufacturer claims they will last 10-20 years and for some people they do but for those of us that use them a lot and in certain applications they definitely don't. The lawyers will say that it depends on the application and I think that the lawyers would say the same thing here to. There's a reason that they don't guarantee cats actually last 10 years.

 

[Ashful]

Cleaned both chimneys and swapped out both cats for new ceramics yesterday. Chimneys have been getting a little dirtier each year, not unusably so, but I'm anxious to see how much cleaner they are next year with new combustors. These things tend to drift out of memory over the course of a few years, since my last cat swap.

Here's the basic summary:

Stove 1: 30 feet of chimney (measured from stove floor)
6 cords burned last year
~4500 hours per year
Pipe was totally clean except bottom 3 feet and top 2 feet. Draft was somewhat affected, so likely some buildup on screen, but it's honestly too high off the ground to see or inspect without aid of drone or scaffolding. Total sweepings was over a pint, maybe approaching a quart, definitely dirtier than prior years:



Stove 2: 15 feet of pipe, or 16-17 measured from stove floor
<3 cords burned last year
3000 - 3500 hours per year
Total sweepings were less than 1 pint, nearly all at the bottom of the pipe.



Old cat removed from stove on the short pipe still looks good, at least visually:



Forgot to take a photo of "beta 3" cat from 30 foot stove, that one is on its way back to cat manufacturer for analysis.

My theory is that all BK's likely deposit most of their crap at the bottom of the pipe, maybe during bypass phase. Very tall pipes (my 30 feet) get a second accumulation at the top, due to gasses cooling on the way up, which the shorter pipe does not suffer.

Both stoves got new ceramic cats. I don't like running steelcats in Ashfords, as they're more apt to clog in these stoves, based on my ~100 cords experience with Ashford 30's running both types.

 

[Highbeam]

Cleaned both chimneys and swapped out both cats for new ceramics yesterday. Chimneys have been getting a little dirtier each year, not unusably so, but I'm anxious to see how much cleaner they are next year with new combustors. These things tend to drift out of memory over the course of a few years, since my last cat swap.

Here's the basic summary:

Stove 1: 30 feet of chimney (measured from stove floor)
6 cords burned last year
~4500 hours per year
Pipe was totally clean except bottom 3 feet and top 2 feet. Draft was somewhat affected, so likely some buildup on screen, but it's honestly too high off the ground to see or inspect without aid of drone or scaffolding. Total sweepings was over a pint, maybe approaching a quart, definitely dirtier than prior years:

View attachment 316804

Stove 2: 15 feet of pipe, or 16-17 measured from stove floor
<3 cords burned last year
3000 - 3500 hours per year
Total sweepings were less than 1 pint, nearly all at the bottom of the pipe.

View attachment 316806

Old cat removed from stove on the short pipe still looks good, at least visually:

View attachment 316807

Forgot to take a photo of "beta 3" cat from 30 foot stove, that one is on its way back to cat manufacturer for analysis.

My theory is that all BK's likely deposit most of their crap at the bottom of the pipe, maybe during bypass phase. Very tall pipes (my 30 feet) get a second accumulation at the top, due to gasses cooling on the way up, which the shorter pipe does not suffer.

Both stoves got new ceramic cats. I don't like running steelcats in Ashfords, as they're more apt to clog in these stoves, based on my ~100 cords experience with Ashford 30's running both types.

View attachment 316805

I forgot that you were using a beta catalyst. Do you think that contributed to the long life? I expect that would be the point of the new recipe.

In that last photo of the ceramic cat, is there a flange on top too? I think mine had three flanges and I put the third on the bottom. Opposite of you if yours had the third. I can't imagine how that would matter.

 

[Ashful]

I forgot that you were using a beta catalyst. Do you think that contributed to the long life? I expect that would be the point of the new recipe.

In that last photo of the ceramic cat, is there a flange on top too? I think mine had three flanges and I put the third on the bottom. Opposite of you if yours had the third. I can't imagine how that would matter.

Mine's same as yours, three flanges. I always put it on top, although I can't remember if there was any reason behind that. Maybe I'm copying what the dealer or BK did, when the stoves first arrived at my house, but I can't even say for sure.

BKVP will have to comment on the life. I do think that was one of their primary goals in switching to this coating, but can't say for sure. It will be interesting to see what the analysis shows, if they're willing to share it with me/us.

 

[bholler]

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.

There are also many like me who see no noticeable wood savings