BK or NC-30?

begreen said:

What is the difference between closing down the air 5-10 minutes after reloading and closing a bypass? It's trivial. Most non-cat stoves I have owned can run from about 400F stove top to 700F stove top depending on how it's loaded, air setting, timing and the fuel choice. That gives one a fair amount of control. The thermostatic control on the original VC stoves also did this automatically, in a non-cat stove. The main advantage of the cat is longer burn time which is great. However that doesn't mean a home can't be heated comfortably with a non-cat stove. It's done all the time.

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As I recall, you've never run a cat stove and are at home most of the day to futz with the noncat. The noncat at 400 is making way more btu than a cat stove with a little 400 degree hot spot on the stove top above the cat. You can manage to be very comfortable with a noncat. It just takes way more work and wood. I know, I have both and have used both to heat the same house.

ohlongarm said:

You will need a forest literally to provide you with enough wood if you choose the NC.Everyone I know three folks say they eat would in astronomical quantities.Especially with a 25 foot chimney. A no brainer for me a BK.

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They must be heating a large space. Will a Blaze King really use less wood? To my understanding a cat will use close to same amount of wood but has the ability to extend the burn time.

ckr74 said:

They must be heating a large space. Will a Blaze King really use less wood? To my understanding a cat will use close to same amount of wood but has the ability to extend the burn time.

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The cat stove is more efficient and will use less wood but it's not that dramatic. In my case I dropped from about five cords per year to four by switching to my bk. Yeah, that's something and yes it will pay for that replacement cat pretty quickly.

My BK uses "way" less wood than my old Jotuls. By "way", I mean I could rip thru a cord per WEEK in the Jotuls, and not be as warm as I am on a cord per MONTH in the BK's. This is not a non-cat vs. cat thing (both were cat stoves), but a radiant stove vs. convective stove thing. Surround a radiant stove on five sides with exterior masonry, and very little of the heat you generate will stay in your home.

As to the "black box" comments, BK's will burn with flame shows if you run them as fast and loose as an NC-30. The beauty of a BK is that you have both options. I don't need flame show when I'm asleep or at work, so I have the BK's turned down suitably at those times.

I have photos of two Ashford 30's installed in my house, that I can post tonight, if you want to see them. I'm sure they're already posted somewhere on this forum, but I'm not having luck in finding them. They burn nicely with flame show at a medium setting or higher.

Highbeam said:

All stoves smoke all the time on reloads. The EPA ratings are time averaged to account for the variable nature of solid fuel combustion.

You make a good point though that if your cat is 80% effective then your emissions have increased over the initial output. THAT is why cat stoves are required to be cleaner burning than non-cats. The allowable emissions rate from a cat stove is like half of what the non-cat guys are required to accomplish to account for the degradation of the cat over its lifecycle.



Note the fine print.... a well treated cat is one that isn't used. A cat in a stove that is not used has an infinite lifespan. Most sources say the cat has a "life" of 10,000 hours or 6 years assuming an arbitrary burning amount per year.

So how long is your burn season? How many hours per day do you expect to burn? We can calculate the expected life of your cat which is not a big deal to replace. Way easier than the door gasket which you will need to replace as well.

The other thing is that a new cat is super awesome. It is extra reactive. So much so that you may be willing to prematurely replace the cat just to keep tip top performance.

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As of May 15, 2016, all stoves must make 4.5 gr/hr. Effective May 16th, 2020 all stoves must make 2.0 on crib fuel. EPA no longer differentiates between technologies.

Starting with a radiant only non-cat epa stove i put an eco fan on it and got more even heat throughout the house without changing my wood consumption.

From there we traded into a radiant/ convective cat stove, a bk ashford 30, and used 'a lot' less wood the following winter.

My data is confounded by three items:

one ongoing air leak repair. My house is sealed up pretty darn good, but repairing an air leak 1/16 x 1/4 inch is worth at least $10/wk when outdor ambients are -20dF and colder.

Two, the two winters i have had the bk30 were milder than the average set while i operated the non cat. This is esp important because my insulation envelope works wxcellent down to -20dF, starts slipping between -20 and -35 dF, below about -40dF my oil burner runs 56 minutes per hour and struggles to keep the house at +60dF without the woodstove helping.

Three, he same summer the BK was installed my youngest daughter ( long hair, two bushel baskets of beauty products) moved out to continue college out of town.

Allowing for all that it looks like switching out stoves cut my wood consumption by some 15 to 40%. I conclude the BK advertising claim of 25% drop in wood consumption is a reasonable claim for them to make.

I wasnt going to keep a kid away from college or stop maintaining my house to have better data today.

Highbeam said:

The cat stove is more efficient and will use less wood but it's not that dramatic. In my case I dropped from about five cords per year to four by switching to my bk. Yeah, that's something and yes it will pay for that replacement cat pretty quickly.

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That's 20% less wood. Good in my opinion.

Ashful said:

My BK uses "way" less wood than my old Jotuls. By "way", I mean I could rip thru a cord per WEEK in the Jotuls, and not be as warm as I am on a cord per MONTH in the BK's. This is not a non-cat vs. cat thing (both were cat stoves), but a radiant stove vs. convective stove thing. Surround a radiant stove on five sides with exterior masonry, and very little of the heat you generate will stay in your home.

As to the "black box" comments, BK's will burn with flame shows if you run them as fast and loose as an NC-30. The beauty of a BK is that you have both options. I don't need flame show when I'm asleep or at work, so I have the BK's turned down suitably at those times.

I have photos of two Ashford 30's installed in my house, that I can post tonight, if you want to see them. I'm sure they're already posted somewhere on this forum, but I'm not having luck in finding them. They burn nicely with flame show at a medium setting or higher.

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From a cord a week to a cord a month? There's got to be more to that story.

It sounds like you may be comparing the Jotuls on the coldest days to the BK's in milder weather.

tarzan said:

From a cord a week to a cord a month? There's got to be more to that story.

It sounds like you may be comparing the Jotuls on the coldest days to the BK's in milder weather.

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Actually Ashful has incredibly good data, though i have only seen a fraction of it. The main thing is he owns a colonial era stone pile with cavernous fireplaces.

His stoves go inside the room szed fireplaces. His old Jotuls did a great radiant job of heating up the stone, which the stone very naturally conducted through the walls to the lawn.

His new convective stoves heat air between the steel firebox and cast iron jacket, the warm air is blown out into the living spaces with low wattage fans and his wood consumption plummeted.

The difference is he stopped radiantly heating stone walls and started using convection to heat air.

Poindexter said:

Actually Ashful has incredibly good data, though i have only seen a fraction of it. The main thing is he owns a colonial era stone pile with cavernous fireplaces.

His stoves go inside the room szed fireplaces. His old Jotuls did a great radiant job of heating up the stone, which the stone very naturally conducted through the walls to the lawn.

His new convective stoves heat air between the steel firebox and cast iron jacket, the warm air is blown out into the living spaces with low wattage fans and his wood consumption plummeted.

The difference is he stopped radiantly heating stone walls and started using convection to heat air.

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That's basically the sum of it. But, tarzan also has a point, as the cord per week quote was based on a particularly cold time of year, not an average over a whole season.

That aside, I am definitely burning less oil AND less wood, since switching to the BK's. Yes, that's even compensating the numbers by the this year's lower-than-average heating degree day count. I do have data, but since this past winter was so far outside the norm, I wanted to wait another year and get a "normal" winter's data on the books before sharing any numbers.

My main issue with the BK stove is that around here we get a lot of rainy days in the 50's where I will want to still run my stove. Will the BK run on those days without making a smoke smell in my house or am I better off with a non cat.

The BK will run as well as any other stove in warm weather. However, you will need good chimney height if your goal is running the BK lower than any other stove in warm weather.

A lot of the comments you hear about BK, such as the black flameless window, are only applicable when you're pushing the burn rate rate below that of any other stove. You don't need to burn it that way, but the beauty of it is that you can.

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troy-pit said:

My main issue with the BK stove is that around here we get a lot of rainy days in the 50's where I will want to still run my stove. Will the BK run on those days without making a smoke smell in my house or am I better off with a non cat.

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Flue height will likely dictate how well your stove runs on these type days.

We get a good amount of days like you describe here in the shoulder season. Maintaining a low fire is easily done but getting a fire started on such a day can be challenging.

I realize some here have had smoke smell issues but I haven't experienced that with the Princess. I don't see a real difference in cat vs non cat on cooler days as far as maintaining a fire on my flue but I do prefer the cat stove do to its ability to run so low and not overheat the house.

troy-pit said:

My main issue with the BK stove is that around here we get a lot of rainy days in the 50's where I will want to still run my stove. Will the BK run on those days without making a smoke smell in my house or am I better off with a non cat.

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As above. The first year i had 14.5 feet of stack, collar to cap on my bk a30. I added one foot to 15.5 feet total ( manual calls for 15 feet minimum) and noticed the difgerence mostly on th shoulders.

At -20dF i think the ashford 30 will run great on 12 feet of stack unless you got some miracle insulation envelope.

To run the stove on a low setting at +50dF i need both 15 feet of stack and cord wood at 12-14%MC - manual calls for 13%.

Iirc the op had 25 feet of stack, so should have no problem with a bk size 30 stove in shoulder season - if he follows the rest of the directions in the manual and gets his wood as dry as specified.

There was one guy last year with plenty of stack javing draft issues with his a30. I suggested -twice- that he should brush out his flue to rule out restricted flow, but he added 8 more feet of stack instead.

Judging by the pics of the stack being added - with a crane- his house was on a very steep slope, but i still think brushing out his exisitng stack before he spent all that moolah would have beem prudent.

If you are having draft issues for more than a couple days and across a change in weather systems brushing is a whale of a lot cheaper than renting a crane and might solve the problem.

I have two Ashford 30's, and I now forget the exact chimney heights, but they're somewhere on the order of 15 feet and 29 feet. The stove on the shorter chimney will stall on a very low burn setting when the weather is in the 50's, which is unfortunately exactly where I want to run that stove when the weather is in the 50's. I settle for burning only overnight (not during the day), at a setting which might correspond to the minimum burn rate of a non-cat, in that stove on days over 50F.

The stove on the taller chimney is never an issue, in any weather. I have run it on the lowest setting on days with outdoor highs peaking to 65F in the shoulder seasons.

I've got a 30NC. My house is 2500 sq. ft., open floor plan, 12 ft. ceilings and well insulated. We heat the entire house with the stove. Furnace is only used for back-up.

That said, I burn about 3.5 cords for a mild winter and up to 6.5 when it's a harsh winter. On the coldest of days I'll put 1.5 wheel barrow loads through it.

I love the stove and it produces an enormous amount of heat, but it does use a significant amount of wood.

I don't know anything about cat stoves to compare it to.

troy-pit said:

My main issue with the BK stove is that around here we get a lot of rainy days in the 50's where I will want to still run my stove. Will the BK run on those days without making a smoke smell in my house or am I better off with a non cat.

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It's not a problem. I heat from September through June in our climate. Plenty of burn days with outside temps in the upper 60s on my 12 foot chimney. No smoke smell in the house.