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cat vs. non-cat - pro's and con's

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Joful, Jun 6, 2012.

  1. BrowningBAR

    BrowningBAR Minister of Fire

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    And, just to be clear, I will be heating with a 30 this year once the Heritage is sold.

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  2. begreen

    begreen Mooderator Staff Member

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    I think there is no argument that the 30NC or a big Drolet represent great value. But there are cost saving compromises and differences.

    PE Summit, ~$2200 steel stove with a better baffle system, no burn tubes, full outer jacket, heavier gauge metal, etc..

    The BK is not just a stove that has a cat added. It has a lot of engineering tweaks that make it perform well. This is particularly beneficial with softwood burning. Ultimately you are paying for ease of use, extended burntimes and long term durability. Evidently this is a good formula. They sell well.
  3. BrowningBAR

    BrowningBAR Minister of Fire

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    Speaking of the Summit, it is one of the few stove I find less appealing than the 30 or the Blaze King. The damn thing looks like a Microwave.
  4. Highbeam

    Highbeam Minister of Fire

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    I'd like to think that all of the same can be said about the NC30 but at a significantly lower price.

    My ideal setup would be a BK princess in the house and a 30 in the shop. These stoves are top two on my list for different reasons but they are at the top.
  5. begreen

    begreen Mooderator Staff Member

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    Sounds like a good combo.
  6. BKVP

    BKVP Feeling the Heat

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    This is a great thread and I would like to add just a bit of clarity if I might. First, the observation that the cat stoves burn dirty and stuff can go out the chimney when the cat fails is accurate. However, for the better part of a decade (average lifespan in our products and we now have a 10 year warranty on our cats) 100% of VOC's are destroyed when the cat is above 550F. As well, about 65% of methane is also destroyed. As a manufacturer of both current technologies, I can assure you that is not the case for non catalytic models.

    As for moisture levels in fuel, lab studies have shown that hardwoods burn dirtier than soft woods, both cord wood and pellet. Also, hard woods do take longer to season (dry out) than soft woods. Additionally, any manufacturers lurking about in this forum can coo berate the fact that the first hour of combustion sees the greatest reduction in fuel weight as a result of water being boiled out of the fuel. So if you burn your stove, cat or non cat for an hour or so on a high burn setting and then shut it down for the day or evening, you can mitigate most of the issues surrounding moisture in fuel. I say most because regardless of combustion technology, moisture in fuel results in dirtier emissions so we should all endeavor to burn as dry a fuel as possible.

    Are you familiar with the term cold starts? EPA has coined this phrase and is looking for data relating to emissions during the restarting or refueling of a cold wood stove. Factually, some of the cleanest burning non catalytic wood stoves can take up to 45 minutes to reach clean burning status. Once all the mass is up to temperature, the stoves burn exceptionally clean. The problem of course is they are relit much more often than a large catalytic wood stove. As for reaching clean burning status in catalytic stoves, once the cat gets above 550 clean burning has begun and we have seen this happen in as little as 9 minutes with specific substrate materials.

    As far as heat output, boy marketing guys are good! Fact, the EPA says there are 8,600 Btu's in a pound of hardwood fuel. Regardless of whether it is 8,600 or 9,000, just remember it is limited. So when you are shopping for a new stove, just look at the total amount of weight in pounds the stove can hold with fuel at 20% moisture content ( a nice round average although not ideal). If a stove will hold 50 lbs. of wood at 20%, then it has a maximum total Btu production of 430,000 Btu's from that load. As manufacturers we can't fudge that number.

    Then locate a brochure for the stove from prior to 2008 (when the Fed. Tax Credit allowed nearly every stove to be eligible for the tax credit) and get the HHV (high heat value) efficiency for the stoves. Most were around 78% on the brochures for the LHV, so just subtract 10-11% and you'll get the HHV value.

    Back to the example above, so the stove has 430,000 Btu's in the load and has a HHV (real world) efficiency of 68%. That leaves 292,400 Btu's to actually heat your home. Divide that by burn time and you can easily get the average heat output of the stove. If a stove has a low burn time of 10 hours, that 29,240 Btu's per hour in your home. If the high burn times is 5 hours, you get 58,480 Btus's AVERAGE into your home.

    All the rest is marketing.
    MarkinNC, Gark, fox9988 and 4 others like this.
  7. dafattkidd

    dafattkidd Minister of Fire

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    How does the industry officially define burn time?
  8. Slow1

    Slow1 Minister of Fire

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    It seems that it is defined however the marketing department of whatever stove manufacturer wants to use it... in other words - there isn't a 'legal' definition of the term so it is used inconsistently. You can perhaps get a sense of things another way - take the formula that BKVP gave and run it another way - when you see the marketing material given by a stove manufacturer, they often give the stove output in BTUs - so, take the total amount you can put in the stove (say the 430,000 in the example BKVP used if that is what would fit in that stove) and divide it by the rated output of the stove and see if it matches what they are claiming for burn time... However you want to define the burn time, you can figure out the average output during that time if you know how much fuel is in there eh?
  9. Highbeam

    Highbeam Minister of Fire

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    Do you suppose that the efficiency is the same for a non-cat trying to burn 10 hours as one trying to burn the same load in 5 hours? Since the efficiency percentage is directly related to this calculation, any variability will directly effect the results.

    I always thought that a non-cat at med/high outputs was far more efficient then a non-cat choked down for max burn times.

    I notice that BKVP convenienty left out, or wanted us to solve, the efficiency of the BK cat units which is well above the standard.

    I have an honest question. BK cat stoves are awesome at low and slow. How do they do at hot and fast? How hot can you get the stove? Would it make a decent heater for the shop where a fast warm up is important? I would honestly have a hard time burning anything other than dry fuel after years of learning how important that is with the non-cat stone stove in my home.
  10. TX-L

    TX-L Burning Hunk

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    I have burned my BKK at full air for a period of time with the cat engaged, hot and fast as you described it, just to see what she would do. My stovetop, even with the fans on high speed, was approaching 800::F, at which point I backed the stat setting down; no need to get crazy. The firebox was a raging inferno, the cat was brilliant red. I don't know if/how this might degrade the cat over time with repeated cycles, and this is not necessary for a house, but might be wanted in a shop for initial heat-up. It seems like one member, Solar and Wood, said he burns his at a "3" setting (high) with his fans on high when it's cold out and has 12 hour reload cycles, but not sure what his stovetop is during this time. Wood type and draft would certainly affect the operation.
  11. jeff_t

    jeff_t Minister of Fire

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    Yep, 800 isn't hard to do. I have my thermometer in the center of the stove, right in front of the convection deck, which is pretty much on top of the cat. One of these days I will get an IR to see how the rest of the stove runs. That's a pretty big piece of metal giving off a lot of heat at those temps. I have come home to the house in the mid 50s, with the stove just warm to the touch, and been at 75 in less than two hours. Of course, that's just the air temp. Everything in the house was still cold, and didn't feel really good until the next morning.
  12. Highbeam

    Highbeam Minister of Fire

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    Three thousand dollars! Ugh, why must they cost so much?
    fox9988 likes this.
  13. jeff_t

    jeff_t Minister of Fire

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    Because they can?
  14. Todd

    Todd Minister of Fire

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    Applied ceramics says not to burn cats at continuous temps over 1600 or it will degrade cat life. I can easily reach those temps if I burn at higher air settings. It's probably ok to get her up there once in awhile but if you need that much heat get a bigger stove.

    Maybe the BK stoves tstat keeps the cat temps down below that threshold even running at higher settings?
  15. BrowningBAR

    BrowningBAR Minister of Fire

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    I'm sticking by the numbers I've seen and three grand for a large stove is right about middle of the road. Though, I do believe the BKK is north of four grand on the east coast.
  16. dafattkidd

    dafattkidd Minister of Fire

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    That is my understanding of it as well. BKVP i would really appreciate your input on this question. How does BK define burn time as an organization? Is there an industry standardized definition?
  17. Joful

    Joful Minister of Fire

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    After seeing High Valley Stoves mentioned as a catalytic stove option, I saw a very pretty enamel green shallow-depth top-load catalytic stove in this video on their home page:



    However, I don't see this stove anywhere in their product offerings. In fact, it looks more like a Jotul or a Lopi than anything available from High Valley. Can anyone identify this stove? Is it a cat stove?
  18. kingquad

    kingquad Minister of Fire

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    Looks like a VC(Vermont Castings). The older VC cat models had problems. Well documented here. The new 2n1 models seem to be more durable. It's a newer design though, so no long term data available yet.
  19. begreen

    begreen Mooderator Staff Member

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    Looks like a VC stove to me.
  20. BrowningBAR

    BrowningBAR Minister of Fire

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    The primary problem with the older VC cat stoves was maintenance costs and extensive use of gaskets. You had/have to budget in the future cost of the refractory parts + catalyst. Also, every few years you have to replace the gaskets on the fireback, damper, back panel casting, ash pan, double doors, and top loading lid.

    Burning with dry wood in a lined chimney and they run like champs. But, due to the maintenance, it is not a stove that you can fall behind on the maintenance. And this means the majority of the stove buying public falls into this category.

    With the new stove, the refractory parts has been replaced with a far stronger, and seemingly superior material. While a more traditional catalyst is used cutting down on the replacement costs even further. But, it is still a stove that relies heavily on gasket maintenance. Which means most stove buyers will burn it until it is a leaky, uncontrollable mess. I look forward to this, as it means I will be able to upgrade the Encore and the Defiant to the newer models for ten cents on the dollar in the coming years.
  21. BrowningBAR

    BrowningBAR Minister of Fire

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    Correct.
  22. Joful

    Joful Minister of Fire

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    Thanks guys.

    So, if the world has gone non-cat, and the advice I receive here is that non-cat's require babysitting thru the burn cycle to keep the secondaries going while maintaining a low burn (something the cat stoves do naturally), how is anyone getting away with keeping non-cat's going unattended all day and night? Seems I've been getting some conflicting information.
  23. BrowningBAR

    BrowningBAR Minister of Fire

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    Incorrect. Throw less wood in a non-cat for less heat. As long as your wood is dry and your chimney is smokeless, don't worry about secondary burns.

    With non-cat stoves, you burn them one way. Char the wood and adjust the air as needed for a clean burn.

    Cat stoves allow you to stuff the stove full and burn clean at a low burn, if needed. Some folks do not need this option. Others do. It is your choice.
  24. rdust

    rdust Minister of Fire

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    I had a non cat(Lopi Endevor) before the BK and I didn't have to babysit it once it was settled in. The first hour or so of the burn could be interesting as it headed for 700+ but after it settled in it was fine. Of course it didn't burn "slow and low" which is the main reason it's gone. If I was around I'd open the air up near the end of the burn to help burn the coals up but other than that it worked "ok". The secondaries are only going to burn at the beginning part of the burn so after a couple/few hours they're typically long gone. Some non cats may burn low better than others but my Lopi was up and down, no way I could ever get a steady low burn out of it with a full load. If I wanted it to burn low I loaded smaller loads which was a PITA since I'm still working age and don't have the time to be loading small loads to control output. With the BK I load it up and forget about it for hours and hours and hours. ;)
  25. begreen

    begreen Mooderator Staff Member

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    Believe me I am not a fire babysitter. I love that I can load our stove and once the air control is on low, walk away until 6-8 hrs later with a full load.

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