WS Ideal Steel or BK Ashford for me?

I can close the draft fully on my Ideal Steel if the fuel is involved and the fire well- established. The glass turns black and the entire inside of the stove is coated with black, soft, sticky creasote afterward but the combustor cleans it all up and no smoke leaves the stove and no creasote is found anywhere after the cat. The I.S. will run impressively slowly.... actually amazingly slowly, without making a mess or becoming inefficient.

Brian

 

You can do the same thing on the PH if the fire is well established, that's a different story. If I have a fire going with secondary's burning, you can shut it complete down and it will slow way down, sometimes even go black. But your too late at that point to do a real low and long 24 hour burn....

 

Very true. I'm having better luck keeping the Progress cat from stalling since I added a couple feet of flue.

 

I have not found that to be the case on the I.S. But of course the entire load of fuel must be at least pretty warm (above 500F) before shutting down the draft of the stove will just smolder. I suppose it could go on like that for 24 hours or even more but really, who cares as that is not a 'burn' IMO, it is just making a mess and producing no appreciable heat.

As long as I can keep a 300F degree temperature differential between the top of the firebox and just above the combustor, I can close the draft completely (such as completely as possible given the minimum built into the stove of course) and get a perfectly acceptable burn. That does require a fire be started with a lot more draft and get up to temp. before damping it so low.

I can reload the stove over a hot bed of coals and immediately shut the bypass and draft to a hash mark or two below 1/4 open (the first major hash mark on an I.S.) and it will reliably burn cleanly though.

Brian

 

I wonder if your easy lightoffs will continue after the SS cat breaks in more. They tend to be hyperactive for a while and then settle down.

 

I thought it was bad for the cat to immediately engage after reload?

 

Yep, at some point the cat. will certainly deteriorate but I am well past the hyperactive part which is only about 100 hours or so. With a new stainless steel cat., I find I can 'light' it with a sheet of crumpled up newspaper but that does not last an entire week. Just an absolutely wild guess but I would expect this kind of performance for 2 years or so, maybe a bit more as the cat. is positioned directly above the highest spot in the firebox (where it receives the max. heat possible from the firebox).

Brian

 

Not that I know of and I have not seen any negative results; I have been doing this for years with different stoves. If the stove is hot and there are sufficient coals to cause the new wood gas to stay hot right after a re-load, I close the cat immediately and set the draft for the duration of the entire load of fuel. The cat. temperature will of course drop during the reload as the bypass as well as the stove door are open but once it is buttoned up and a reasonable amount of [warm enough] gas is fed to the cat., it will immediately re- light. By immediate, I mean less than 10 seconds and given sufficient draft, it will glow again w/in 20 to 25 seconds.

As far as 'bad', I think the only bad thing for a catalytic combustor was thermally shocking the cat., which reloading the stove kinda' does no matter what. But at any rate, thermal shock only applied to ceramic cats. anyway and all modern cats. supplied in current stoves that I know of are stainless steel foil and that is not capable of breaking / cracking from thermal shock. At any rate, I have not found even ceramic cats. were particular delicate and while they do tend to crack 'here and there', they still work fine unless they crumble outright which has only happened to me when removing them.... 'cause they had fine cracks in them from use already.

Brian

 

As long as the wood is dry, it's not a real big deal. Dry on the outside, that is, i.e. no rain, snow, ice. According to someone at blaze king, leaky door gaskets are the biggest cause of thermal degradation.

I could close immediately loading on hot coals, but I usually give it at least five minutes or so.

 

24 hour burns was not a design goal of the Progress Hybrid. I am able to shut completely (in colder weather) my air and flue damper and bypass within m oments of loading. I get nice long burns, but not 24 hour burns.

 

Same here. Today I loaded with Oak at 4am and shut it down completely. 13 hrs later the stovetop was about 250F with tons of hot coals for a quick reload.

 

How long will the precious metals coating on the stainless steel catalyst typically last? I know we have gone back and forth on the IS cats estimated longevity and 2-3 years was what we were coming up with. Is it possible to recoat a cat?

 

I had that very thought and thought it was a great idea; we could send in our old cats, have them blasted and re-coated; we would save a few bucks and the company(s) doing the coating would not have to make new cats, just re-coat the old ones.

Then I thought about it for a bit and realized it will not work: their process will involve coating the raw "VVVVVVV" shaped S.S. foil, and it will be a full- blown production environment. The last thing they would want is all different size and shape cats. coming in, especially with some in cans, some having flanges and on and on, and all would have to be handled individually. There would never be enough of one type of combustion to make it worthwhile, and their process must depend on easy and consistent access to both full surfaces to manufacturer. So in the end, it would be far, far less expensive to make a new cat., at least the active part of it, than to refurbish old ones.

As to the failure mode, I do not know 'how' the combustors fail really. Some amount of coating happens (often called 'poisoning' the combustor) but I do not know if that is the major failure mode or not. It could be that keeping the substrate (the metal foil or the ceramic matrix) so hot for so long, the coating just gets ejected from the surface so there is less and less catalyst there in the first place? We know autos have the same basic type of catalyst and they easily go 100,000 miles but they do degrade also. They run in a much more controlled environment with far fewer contaminants so their failure mode would seem more likely to be losing the catalyst off of the surface. So just for chuckles: let's say an auto catalyst lasts 100K miles, and the average speed was 45 MPH (pulling this right out of the sky but I need something to get an idea of how many hours a car can use a catalytic converter), then the hours on the converter would be 2,222.22 Hmmmmm, that is pretty similar to the good, active life of a combustor in a woodstove I think. So that would lead me to believe that combustors fail or wear out due to losing the precious metal coatings on the surface, and they must go 'up the chimney'.

But that is all conjecture on my part and is probably worth what everyone paid for it so take it with a big grain of salt. There may be much better info. out there on automotive converters regarding lifespan, their failure mode(s), etc. ??

Brian

 

At what temperatures do automotive cats work at? And it's interesting that they don't fail sooner compared to a wood stove cat. Are they made the same way?

 

I've done some of those quick light offs at times as well but wouldn't make it SOP, could eventually cause masking of the catalyst, especially if your wood and or draft isn't ideal.

I do like how the steelies resist thermo shock and seem to last longer but I also think the ceramics produced a little more heat for some reason at least in my experience.

 

I think trying to compare to a vehicle is futile.
But...
There are a ton of variables to consider. Not just run time, but volume, temperature, cylces, actual particulate exposure etc.
The only hour meter I look at or vehicle that has one is my father's pickup. It has roughly 4400hrs and 130k? On it? 6.0 liters per revolution or rpm( even if it idled its whole life)at idle of 700 rpm for 4400 hours have moved how much volume? Then figure out how clean or dirty the motor runs and how much scrubbing the cats actually do....
Does it matter if you can't compare it to a wood stove cat? How do you calculate wood stove flue volume....
A vehicle with short run times before the cat lights off will shorten it's lifespan. A vehicle with something not right with the engine such as burning oil or adding too much fuel due to a bad oxygen sensor can and will shorten a cats life or kill one.

I know scrap places offer more money for different brand cats due to their size and better(more) precious metal content. They are ceramic with "lots" of Platinum.

I think it has more to do with operating conditions, a Woodstove cat essentially gets abused and worked. It sees and deals with more particulates than an automotive cat. An automotive cat is used under pretty good and consistent (optimal) conditions. Cars today have cat over temp protection amongst other things, and are built and programmed more or less around a emissions system (catalytic) .

 

Yes, there are too many variables to make any kind of direct comparison, and some, such as how much 'fuel' (hydrocarbons as smoke or gasoline) is going through the cat. is such a huge variable that it all kind of goes out the window.....

But all of that said, the example I used was sufficient for me that both uses, woodstove and vehicle, are w/in the same 'realm of possibility' and as vehicle converters are not generally poisoned, it leads me to believe that our woostove cats. also fail in the same manner, loss of catalyst over time.

Along the same lines, I think the real problem with woodstoves is not contaminates but time; some cat. mfgs. claim a combustor life of upwards of 12,000 hours. Again, compare that with vehicle use and it quickly shows that it is not likely to ever reach those kinds of time and still work w/in acceptable parameters (read: passing an emission test or not throwing an error code). My own experience shows me, repeatedly, with multiple stoves and combustors, ceramic as well as S.S., that they fall off significantly in performance before two full seasons of dedicated (exclusive heating with) woodstove use. Again, tough to calculate how much gas has actually moved through the cat. but using very rough, 'rule of thumb' calculations: burning 24/7 for 5 months is 3,000 hours. My experience is that all the cats. I have seen have deteriorated to the point that they are difficult to use, very difficult to light and worst of all, difficult to keep 'lit' (I have had them stall for an entire burn and it makes the same mess an old Smoke Dragon does when damped down too far) before two years, which would be 6,000 hours. Again, very rough, but maybe enough to get some kind of handle on how they deteriorate. And let me add that while I usually find End Of Life is around 1 1/2 years, it is not a pleasure running the stove with a one- year old cat. either as they are getting resistant by that point.

The up- side is that putting a new cat. in the stove is FANTASTIC..... Like sex, only good!

Brian

 

We're on the same page but I disagree that auto cats don't get poisoned. I believe like I suggested "poisoning" is the leading failure of automotive cats. It's common for cars to go over 200k on the original cat, Doubling your original estimate.
Modern engines have triple fail-safes nowa days protecting cats and emissions from "poisoning".
Woodstove dont. They are crude and prone to user error. Stoves aren't adjusting or calculating grams per milisecond afr temp fuel quality cat temp egt etc...
I think if you could control what the combustion process does in a Woodstove like a motor results would drastically different. Not just in cat life but overall emissions and efficency. Maybe that's the way of the future....computer controlled Woodstove!

I also think some auto cats are made with a much stricter process and quality than Woodstove cats.

 

Well, twice as much as a 'windage guess' is still fine. Again, it was not even an estimate, just some way to try and relate the two and the only thing I could and can think of is hours. And I am satisfied with my admittedly poor guesstimates that both fail in a similar range of usage.

The reason I discount coating or 'poisoning' is because we can do a pretty effective job of cleaning a woodstove cat.. Again, I am assuming it is much, much cleaner (less coated microscopically) than it was before this type of cleaning and early on, they respond very well to this cleaning. But as time accumulates and cats. become progressively more sluggish, the cleaning also has a greatly reduced effect on them; this is the 'evidence' that leads me to believe coating (or contamination, or poisoning- all the same thing for our discussion I believe) is not the problem, the loss of catalytic materials from the surface is. From there, I was just projecting that 'evidence' onto vehicular converters but that was pure conjecture of my part and I have no idea of the failure modes or percentages (partly loss of material, partly coated, partly the catalyst itself being altered, etc.) of the modes there might be.

I think it is important to bear in mind here that we are merely having a conversation, not actually exchanging or weighing 'evidence' because there is precious little of that, at least for woodstoves. And while I believe there IS far more available about vehicular use, it is not available to me, at least as far as I know. And on top of that, I believe 'we' (most people discussing this topic) are generally agreed that 1) cat.s fail fairly rapidly, and certainly far faster than manufacturer's have indicated and 2) regardless of the failure mode, they are not restorable, at least not by any method known to 'us' (certainly not known to me or I would be using it ).

Another thought though, relating to what you mention about user error, miss- use, etc., is that they last a surprisingly long time when looked at from that point of view; a combustor in a stove, burning variable fuel, under wildly varying conditions, temperatures and flow rates, and always running hot enough to cause deterioration to the underlying substrate and they still last for a thousand hours and more. Platinum is a soft metal, and there is very little of it on the surface of the base material in a catalytic combustor so view this way, it is kind of surprising to me that there is enough left, by the second fire, to work at all.

Brian