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Do cat elements normally crack, at all?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Highbeam, Jul 30, 2013.

  1. Highbeam

    Highbeam Minister of Fire

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    So I was doing the summer deep clean of the flue and stove over the weekend. Swept the chimney and then vacuumed every bit of everything I can get out of the firebox.

    Well I pulled off the cat shield and inspected the cat. It was a nice grey color, even all the way across. I was using a nice bright LED Cree flashlight and I noticed that there are cracks diaganol across each of the three cells that make up this large cat. No material has fallen or is eroded but the light shines through these fine cracks.

    I burn well well seasoned wood. No overfires, the stove has worked very well. Is this typical? Should they look new for the 10 years?

    I took some pics but you can't even see the cracks.

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  2. begreen

    begreen Mooderator Staff Member

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    My understanding is that cats degrade over time. You only get 100% when they are new. There will be more flaws and declining performance, but they will still be functioning. How long depends on the cat design, placement, usage. Normal life used to be more like 5 years, but some report longer.
  3. Highbeam

    Highbeam Minister of Fire

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    Here's photo, fuzzy, but you can detect the cracks from corner to corner. I am not so concerned with the function as much as the physical degradation.

    I have a 10 year warranty on the cat from BK.

    Attached Files:

  4. Tenn Dave

    Tenn Dave Feeling the Heat

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    I would contact BK and see if this is typical. My guess is that it is and you probably have nothing to worry about. But I would check with them just to be sure.
  5. Joful

    Joful Minister of Fire

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    If my cats looked that good after 10 years of 24/7 seasonal use, I think I'd be very happy.
  6. Highbeam

    Highbeam Minister of Fire

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    This is after one year of stove use for primary heating. Our season is long, just under 9 months but not terribly cold so I only used about 3 cords.

    I expected the cats to look like new.
  7. begreen

    begreen Mooderator Staff Member

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    Doesn't look too bad too me, but let's see what BK says. Is the warranty pro-rated like a tire warranty with lots of exceptions?
  8. Tenn Dave

    Tenn Dave Feeling the Heat

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    I think you're right. Give BK a call and see what they say.
  9. Joful

    Joful Minister of Fire

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    So, I re-read the OP, and found only one question contained within:


    Answer: No, they should not "look new for the 10 years." ;lol

    Tough to say much from that photo, but it doesn't look awful.
  10. Highbeam

    Highbeam Minister of Fire

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    No, not awful and in no risk of falling apart but if I have failed to operate the stove correctly or if I need to have another set of cats on stand by then I want to know.

    How's this for a question... Has anybody else noticed thin cracks across the cat elements after just one year of burning? Two years?
  11. A1Stoves.com

    A1Stoves.com Minister of Fire

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    Yes, i've seen them start cracking after a season or two
    typically I replace them on warrantee and request a steel cat replacement. BK has never argued with me about it....
  12. Joful

    Joful Minister of Fire

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    I can say the cat in one of my old Firelights was 19 years old when I replaced it, and no cracks. It was never used daily, but was definitely used.
  13. Woody Stover

    Woody Stover Minister of Fire

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    I think they are generally pro-rated but I don't know about the BKs. e.g. on a five-year, 100% after a year, 80% after two years etc.

    Did it still work at all?
  14. Todd

    Todd Minister of Fire

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    No cracks on my Princess or Keystone's but I have had cracks like that on my Fireview and had it replaced. It's the first sign of failure if you ask me. It will probably still work but who knows how long til it starts to crumble and degrade.
  15. Todd

    Todd Minister of Fire

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    This what Applied Ceramics has to say:
    What causes thermal shock to the combustor?





    [​IMG]
    A sudden temperature change or uneven temperatures to the combustor's substrate can cause cracking.
    One of the main reasons for this happening is refueling with wood containing some form of moisture. This can be wood that has been exposed to snow or rain, or perhaps green wood that has not been stacked and seasoned for at least one year.
    The thermal shock comes when the moist smoke comes in contact with the combustor running at temperatures in excess of 1000° F (540° C).
    The cell walls will develop hairline cracks and eventually pieces will start to fall off the combustor. This loss of surface area means there will be less catalytic surface space and less efficiency of the combustor.
  16. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Yes, with the ceramic cat we did. We've worked with Woodstock, or perhaps I should say Woodstock has worked with us. We did have cracks but the cat still worked fine for quite some time. When it began crumbling is when we switched. They had got the steel cats in so with some prompting from them we put the steel cat in. So far we still like the steel cat better than the ceramic. I can say that there is still more work going on to improve the cats and I'm certain they will continue to improve.

    I also remember our friend from the Yukon who had a BK and I'm sure he said his cat was over 10 years old and still going fine. Unfortunately he has not returned to the forum for a long time now.
    Tenn Dave likes this.
  17. Joful

    Joful Minister of Fire

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    I think so, but can't say for sure. It was installed for my first year of burning, and I had good seasoned wood left by the PO, but no experience or cat probe thermometer to guide me.
  18. Woody Stover

    Woody Stover Minister of Fire

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    I like having back-ups in stock. The warranty is based on date of purchase, though....
  19. Joful

    Joful Minister of Fire

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    I used to be the same way with, well... everything. No need, though. Should one ever go belly up, you can continue to burn with a damaged cat, and have a new one thru UPS in a day or three.
  20. ddddddden

    ddddddden Minister of Fire

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    I think the key word here is "EPA."==c Cat mfrs can't get jerky with the warranty like some tire mfrs do.
  21. Todd

    Todd Minister of Fire

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    How's your door seal Highbeam? I adjusted mine a couple times last Winter.
  22. begreen

    begreen Mooderator Staff Member

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    That seems surprising on a new stove. Many stoves don't have a door adjustment. What do you think causes this?
  23. Highbeam

    Highbeam Minister of Fire

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    The door tension on the BK is adjustable. Early on, I did add one turn just so that there would be some moderate tension after the new gasket broke in. The door seal is as good as new, with a visible line where it makes contact with the knife edge door frame. I've never been particularly thrilled with the knife edge arrangement on a round gasket but all signs point to a good seal. Long burn times and an evenly (left to right) distributed darkening of the glass.

    One member used some washers to raise the door on the hinge pins to give a more centered engagement. I know that the bottom of the door gasket has way more tension than the top. I nearly ripped a dollar bill testing mine.

    The three year EPA warranty and then the 10 year BK warranty, all with 100% replacement, were actually strong reasons for me to go to the cat stove. Given that I have three years, I may just burn this cat the way it is next season and then reinspect next year.
  24. SolarAndWood

    SolarAndWood Minister of Fire

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    FWIW, this is what mine looked like after a little over 3 years and 25 cord.

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