Blaze King - King on 6" chimney

[rydaddy]

I've done countless searches on here and read through a lot of threads about the topic of running a stove that calls for an 8" chimney on a 6" chimney. I swear there are guys on here doing it, but I have not found threads with a lot of info. If anyone out there is doing it with the Blaze King King I would love to hear your thoughts, suggestions. I am moving early next year and will be heating from the basement now, and have approx. 35' of chimney. Quite probable that I will be building a chase inside the "middle" of the house for the chimney to go up through and to keep the stove as centrally located as possible. 3364 sq. ft, including the walkout basement.

I am currently burning with a Hearthstone Heritage on a 20' liner in the middle of my house through existing fireplace etc. This stove does the job at the current house 1800 sq. ft., but simply doesn't have anything close to adequate burn-time to be a serious heater. It needs a lot of attention.

Thanks in advance!

 

[Todd]

I believe hearth.com member Rich L is burning his King into a 6" chimney. Throw him a PM.

 

[Patapsco Mike]

Do you really need the King? I put three big splits in my Princess at 6:15 a.m. yesterday morning. When I got home from work at 9 p.m., my stove was still above 350 and I just raked the coals to the front, loaded it up, and off she went. That was with just three (big) splits! After 15 hours, every other stove I've ever owned would have been cold.

Just saying... With the solid 12 hour burns of the Princess, you might be better off with the smaller stove and a properly sized flue (unless you truly need 24 hour burn times).

 

[rydaddy]

Do you really need the King? I put three big splits in my Princess at 6:15 a.m. yesterday morning. When I got home from work at 9 p.m., my stove was still above 350 and I just raked the coals to the front, loaded it up, and off she went. That was with just three (big) splits! After 15 hours, every other stove I've ever owned would have been cold.

Just saying... With the solid 12 hour burns of the Princess, you might be better off with the smaller stove and a properly sized flue (unless you truly need 24 hour burn times).

I have a buddy with a 1700 sq ft. ranch with a princess on one end of his basement. He is also telling me to just go with the princess. I am concerned about the real-life total heat output. If this was going on the main floor (which is not able to happen in this house) the princess would probably be the choice. Again, concerned that the extra oomph of the King will be needed in this situation. I would like to purchase before Dec 31st, otherwise I would look very closely at the new Woodstock once it comes out... when it comes out.

 

[Lanningjw]

The princess stove has a 2.8 fire box. My house is just a little smaller than your. Its really some big heat, I dont like bruning until it gets down to 30 degree.
6 inch on the princess stove might be the way to go!

 

[SolarAndWood]

Again, concerned that the extra oomph of the King will be needed in this situation

If you look at the output specs, they aren't that different. The difference you are going to see with the King is burn time.

 

[Renovation]

Hi rydaddy,

I'm want to do the same thing--8" stove output into 6" chimney. Here's what I've learned so far, and my own (questionable ;-P ) thoughts.

I asked Blaze King, and got an email back saying “Sorry, there is an almost ZERO chance the King will run on 6”. That is disappointing, but not surprising, since manufacturers have enough headaches without encouraging non-standard installations.

Then I talked with a guy who does run a King on a 6" chimney, and he told me that his dealer said he could run 8” pipe from the stove up to an 8" reducer at the stovepipe-chimney connection, not at the stove . In other words, he runs 8" stovepipe out of his stove, and then uses an 8" to 6” reducer at his ceiling to connect to his 6" chimney. His 8" stove pipe is single wall pipe. It has two 90 degree bends before connecting to a chimney that he says is 9' above his roof--I don't know if he has 9' chimney total, or more due to attic height, etc.

With that setup he says he gets a little smoke spillage (not sure when, maybe when reloading?), but is happy with his setup, and gets good performance and 15-17 hours of heat.

Those are what I've heard, and here are my thoughts.

First, it seems that keeping the stovepipe 8" until it gets to the chimney is the way to go.

Second I don't want smoke spillage, so if my 6" setup would perform like the setup this guy was kind enough to share with me, I'd go with 8". But that setup has other factors that limit his draft: single wall pipe, two 90 degree bends, using sharp 90 degree fittings for the bends rather than more gradual 45s, and a chimney that may only be 14' including stovepipe.

In my setup I plan to optimize all those factors, by using double wall stovepipe, straight with no bends, and 24' of total chimney.

Third, in their "BlazeKing 101" video (clickable on their home page), BK states that it is possible to overdraft their stoves using a tall 8" chimney. They don't say how much is too much ("consult an expert"), but I'm thinking it's possible that 8" pipe 24' high might do it, and reducing the chimney portion of the pipe to 6" might actually make the draft closer to ideal in my case.

So that's what I've learned and thought, for your use and comment. I want to do it right, and seeing as I already have the 6" pipe, I'm leaning towards the 8" stovepipe into 6" chimney solution. I suppose I could talk to a chimney professional, or look at other resources. Anyone know of charts or calculations for draft and flow versus diameter and height? I'll try Googling that, and post if I learn something.

I hope this helps someone, and invite your thoughts.

All the Best!

George

 

[Renovation]

Again, concerned that the extra oomph of the King will be needed in this situation

If you look at the output specs, they aren't that different. The difference you are going to see with the King is burn time.

Total conjecture (and wishful thinking) here, but might that imply that the 8" pipe might be needed to meet EPA emissions requirements when reloading the King's big firebox, rather than overall performance?

 

[SolarAndWood]

Again, concerned that the extra oomph of the King will be needed in this situation

If you look at the output specs, they aren't that different. The difference you are going to see with the King is burn time.

Total conjecture (and wishful thinking) here, but might that imply that the 8" pipe might be needed to meet EPA emissions requirements when reloading the King's big firebox, rather than overall performance?

Not sure...I have a by the manuals recommendation 8" double wall stove pipe straight up to straight up 8" Class A and the stove works flawlessly.

 

[Renovation]

Total conjecture (and wishful thinking) here, but might that imply that the 8" pipe might be needed to meet EPA emissions requirements when reloading the King's big firebox, rather than overall performance?

Not sure...I have a by the manuals recommendation 8" double wall stove pipe straight up to straight up 8" Class A and the stove works flawlessly.

I hear nothing but flawless performance from BK owners, barring a bad thermostat. ;-)

How many feet of total chimney height do you have, Solar?

 

[rydaddy]

Hi rydaddy,

I'm want to do the same thing--8" stove output into 6" chimney. Here's what I've learned so far, and my own (questionable ;-P ) thoughts.

I asked Blaze King, and got an email back saying “Sorry, there is an almost ZERO chance the King will run on 6”. That is disappointing, but not surprising, since manufacturers have enough headaches without encouraging non-standard installations.

Then I talked with a guy who does run a King on a 6" chimney, and he told me that his dealer said he could run 8” pipe from the stove up to an 8" reducer at the stovepipe-chimney connection, not at the stove . In other words, he runs 8" stovepipe out of his stove, and then uses an 8" to 6” reducer at his ceiling to connect to his 6" chimney. His 8" stove pipe is single wall pipe. It has two 90 degree bends before connecting to a chimney that he says is 9' above his roof--I don't know if he has 9' chimney total, or more due to attic height, etc.

With that setup he says he gets a little smoke spillage (not sure when, maybe when reloading?), but is happy with his setup, and gets good performance and 15-17 hours of heat.

Those are what I've heard, and here are my thoughts.

First, it seems that keeping the stovepipe 8" until it gets to the chimney is the way to go.

Second I don't want smoke spillage, so if my 6" setup would perform like the setup this guy was kind enough to share with me, I'd go with 8". But that setup has other factors that limit his draft: single wall pipe, two 90 degree bends, using sharp 90 degree fittings for the bends rather than more gradual 45s, and a chimney that may only be 14' including stovepipe.

In my setup I plan to optimize all those factors, by using double wall stovepipe, straight with no bends, and 24' of total chimney.

Third, in their "BlazeKing 101" video (clickable on their home page), BK states that it is possible to overdraft their stoves using a tall 8" chimney. They don't say how much is too much ("consult an expert"), but I'm thinking it's possible that 8" pipe 24' high might do it, and reducing the chimney portion of the pipe to 6" might actually make the draft closer to ideal in my case.

So that's what I've learned and thought, for your use and comment. I want to do it right, and seeing as I already have the 6" pipe, I'm leaning towards the 8" stovepipe into 6" chimney solution. I suppose I could talk to a chimney professional, or look at other resources. Anyone know of charts or calculations for draft and flow versus diameter and height? I'll try Googling that, and post if I learn something.

I hope this helps someone, and invite your thoughts.

All the Best!

George

I think you and I are very much on the same page. I'm a firm believer that the chimney is just as important if not more than the stove. And in this case a chimney set-up for optimum draft would make 6" more viable. My heritage was installed without a damper (at the Stove Shop's urging) and i eventually installed one or I was constantly running at over-fire temps. Works much better with the damper. Replaced gaskets umpteen times, had a door replaced on warranty, had dealer at the house to confirm draft issues etc... a $15.00 damper made all the difference in the world (when used properly).

My set-up should allow for a straight chimney. And a long one at that.

 

[SolarAndWood]

How many feet of total chimney height do you have, Solar?

5' of double stove pipe and 20' of Class A

 

[Renovation]

How many feet of total chimney height do you have, Solar?

5' of double stove pipe and 20' of Class A

Thanks Solar!

So now we know that 25' total of straight 8" chimney with double wall stovepipe and class A chimney does not cause overdraft on a Blaze King King. Good to know.

 

[Renovation]

Okay, I've been playing with 6" versus 8" chimney calculations, and have some results for comment, sanity checking, and general ridicule. ;-)

I Googled up this chimney calculator, which is pretty fun to fool around with:

http://www.engineeringtoolbox.com/natural-draught-ventilation-d_122.html?v=14&units=feet#

The part I played with is the "Natural Draft Air Flow and Velocity Calculator" about halfway down the page.

It's in metric, so to use it you have to convert units using the widgets on the left side of the screen, and know that for circular pipes, the "duct hydraulic diameter (m)" is the chimney diameter.

Once I waded through that, the fun began.

I set the interior temp at 68*, outside temp at 20*, and varied chimney diameter and height, in the following format:

Each line shows the chimneyheight/houseTemperature/OutsideTemperature/ and the resulting DraftPressure/AirFlow:


height/dia/insidetemp,F/outsideTemp,F/DraftPressure,N/m^2/flow,ft^3/min

14/8"/68/20/5.2(0.02water")/164
14/6"/68/20/5.2(0.02water")/88
24/6"/68/20/7.3(?water")/103

I found those results kind of interesting.

First, it seems the Draft pressure--the initial draw on the stove--depends on height and temperature only. But the resulting flow also depends on diameter, which determines the chimney's resistance to flow. This seems to say that, for a given temperature difference and chimney height, a 6" pipe initially draws as hard as an 8" pipe, but has lower maximum flow , which all seems to make sense to me. (Of course this ignores bends, single/double wall stovepipe factors, which add their separate effects.)

Comments? Laughter?

You can also see from the two 6" diameter cases, that a taller chimney increases draw significantly, but flow not as much, as the pipe's resistance gets in the way.

I'm thinking this has implications for the Blaze King King too. The King and the Princess have almost the same maximum BTU output, with the biggest difference between the two stoves being a bigger firebox for longer burns. As one member pointed out, air demand is determined by burn rate, not firebox size, so the steady state air requirements for the Princess and King should be nearly identical, making a 6" pipe fine for the King under most conditions.

Right?

The only scenario I can think of where the King and Princess significantly differ would be reloading a hot firebox. Then the King's bigger load of fresh wood might outgas more, and briefly require more air to run the catalyst efficiently and pass EPA. I also note that the King's owner's manual (in the Definitions section under Chimney) says "Never use a chimney connector or chimney flue small than the stove exhaust, unless approved by your local inspector." So an 8" chimney is not a hard and fast rule, but Blaze King doesn't want responsibility for anything smaller.

The two factoids together make me wonder if the reason the King specifies a bigger flue than the Princess with the same output, is to meet EPA emissions standards during hot reload.

Comments? Tomatoes?

One more interesting item. In Definitions under Draft, the BKK manual says it will smoke, burn poorly, and start hard with a draft less than 0.02" of water. According to my calculations ( ;-P ) that is the draft for a 14' high ideal chimney with a 50 degree temperature differential.

All this is of course inconclusive, and I could be completely wrong, but does makes me confident enough to risk installing the 24' high 6" diameter chimney (8" diameter double wall stovepipe up to the thimble) that I have on hand. What I'll do is frame the surface penetrations large enough for an 8" chimney install, making swapping one in relatively painless, if it comes to that.

Comments? lol

Well, there's my geeking out for today. I hope you found it useful and/or amusing.

George

 

[SolarAndWood]

What I'll do is frame the surface penetrations large enough for an 8" chimney install, making swapping one in relatively painless, if it comes to that.

I won't toss any tomatoes but I wouldn't delude yourself into thinking that is relatively painless. Once that 6" pipe is installed and sealed up, you are going to have better things to do with any available weekend than swap the pipe out. You can't get around the fact 8 inch pipe is almost twice the area of 6 inch pipe and the guys designing the stove did a lot of testing before making the recommendations they did. If you read the manual, you will also see they highly recommend double wall stove pipe. My gut tells me that shouldn't make that big a difference either. Maybe you get away with it, maybe you don't. Maybe the system doesn't perform ideally, maybe you don't notice the difference. It wasn't worth the chance to me.

Now, if that 6" pipe were already installed and sealed up in a chase, I would hook the stove up and see how it worked.

 

[rydaddy]

Okay, I've been playing with 6" versus 8" chimney calculations, and have some results for comment, sanity checking, and general ridicule. ;-)

I Googled up this chimney calculator, which is pretty fun to fool around with:

http://www.engineeringtoolbox.com/natural-draught-ventilation-d_122.html?v=14&units=feet#

The part I played with is the "Natural Draft Air Flow and Velocity Calculator" about halfway down the page.

It's in metric, so to use it you have to convert units using the widgets on the left side of the screen, and know that for circular pipes, the "duct hydraulic diameter (m)" is the chimney diameter.

Once I waded through that, the fun began.

I set the interior temp at 68*, outside temp at 20*, and varied chimney diameter and height, in the following format:

Each line shows the chimneyheight/houseTemperature/OutsideTemperature/ and the resulting DraftPressure/AirFlow:


height/dia/insidetemp,F/outsideTemp,F/DraftPressure,N/m^2/flow,ft^3/min

14/8"/68/20/5.2(0.02water")/164
14/6"/68/20/5.2(0.02water")/88
24/6"/68/20/7.3(?water")/103

I found those results kind of interesting.

First, it seems the Draft pressure--the initial draw on the stove--depends on height and temperature only. But the resulting flow also depends on diameter, which determines the chimney's resistance to flow. This seems to say that, for a given temperature difference and chimney height, a 6" pipe initially draws as hard as an 8" pipe, but has lower maximum flow , which all seems to make sense to me. (Of course this ignores bends, single/double wall stovepipe factors, which add their separate effects.)

Comments? Laughter?

You can also see from the two 6" diameter cases, that a taller chimney increases draw significantly, but flow not as much, as the pipe's resistance gets in the way.

I'm thinking this has implications for the Blaze King King too. The King and the Princess have almost the same maximum BTU output, with the biggest difference between the two stoves being a bigger firebox for longer burns. As one member pointed out, air demand is determined by burn rate, not firebox size, so the steady state air requirements for the Princess and King should be nearly identical, making a 6" pipe fine for the King under most conditions.

Right?

The only scenario I can think of where the King and Princess significantly differ would be reloading a hot firebox. Then the King's bigger load of fresh wood might outgas more, and briefly require more air to run the catalyst efficiently and pass EPA. I also note that the King's owner's manual (in the Definitions section under Chimney) says "Never use a chimney connector or chimney flue small than the stove exhaust, unless approved by your local inspector." So an 8" chimney is not a hard and fast rule, but Blaze King doesn't want responsibility for anything smaller.

The two factoids together make me wonder if the reason the King specifies a bigger flue than the Princess with the same output, is to meet EPA emissions standards during hot reload.

Comments? Tomatoes?

One more interesting item. In Definitions under Draft, the BKK manual says it will smoke, burn poorly, and start hard with a draft less than 0.02" of water. According to my calculations ( ;-P ) that is the draft for a 14' high ideal chimney with a 50 degree temperature differential.

All this is of course inconclusive, and I could be completely wrong, but does makes me confident enough to risk installing the 24' high 6" diameter chimney (8" diameter double wall stovepipe up to the thimble) that I have on hand. What I'll do is frame the surface penetrations large enough for an 8" chimney install, making swapping one in relatively painless, if it comes to that.

Comments? lol

Well, there's my geeking out for today. I hope you found it useful and/or amusing.

George

You put some serious effort in there! Well done.

 

[rydaddy]

What I'll do is frame the surface penetrations large enough for an 8" chimney install, making swapping one in relatively painless, if it comes to that.

I won't toss any tomatoes but I wouldn't delude yourself into thinking that is relatively painless. Once that 6" pipe is installed and sealed up, you are going to have better things to do with any available weekend than swap the pipe out. You can't get around the fact 8 inch pipe is almost twice the area of 6 inch pipe and the guys designing the stove did a lot of testing before making the recommendations they did. If you read the manual, you will also see they highly recommend double wall stove pipe. My gut tells me that shouldn't make that big a difference either. Maybe you get away with it, maybe you don't. Maybe the system doesn't perform ideally, maybe you don't notice the difference. It wasn't worth the chance to me.

Now, if that 6" pipe were already installed and sealed up in a chase, I would hook the stove up and see how it worked.

I think you just hit the nail on the head. I am going to spend my time trying to decide if I really need the BKK. If I do, then I will go 8". If I don't need the BKK then I will go 6". Smart move may be to put in the 6" pipe once we move in, run my Heritage for a while (will need a lot more reloading) and see how well it is keeping the house warm.

 

[SolarAndWood]

What is the layout of the new house and where are you? Is your goal to heat exclusively with wood or just put a dent in your fuel bill?

Our house is about the same size and we also have the lower level walkout. The house is essentially a rambling ranch with the walkout basement under half of it. The stove is centrally located in the section of the house over the walkout in an open 1200 sq ft space. The house has a lot of glass facing directly into the predominant wind. With our old 2.5 cubic ft stove, I was considering giving up my fight against the propane man. The King made heating exclusively with wood possible even with my wife and I both working.

Now, that said, the lower level is never warm. In fact, when it is cold and blowing, the water lines have frozen and I have had to put some big electric heaters down there to get them unfrozen. Luckily, they are flex and didn't burst. If I were in your position, I might consider putting the Heritage in the lower level and the King on the main level. I am putting a wood boiler in the lower level to heat the lower level, the extremities and for hot water. I will also likely add an electric boiler for backup.

My guess is that with that big of a house you are going to want the King if your goal is to heat exclusively or nearly exclusively with wood unless you live in a very mild climate.

 

[Todd]

I think 6" will work. Only time you would need 8" is if you were running a full load at max air setting. You will be burning low and slow 90% of the time.

 

[Renovation]

What I'll do is frame the surface penetrations large enough for an 8" chimney install, making swapping one in relatively painless, if it comes to that.

I won't toss any tomatoes but I wouldn't delude yourself into thinking that is relatively painless. Once that 6" pipe is installed and sealed up, you are going to have better things to do with any available weekend than swap the pipe out. You can't get around the fact 8 inch pipe is almost twice the area of 6 inch pipe and the guys designing the stove did a lot of testing before making the recommendations they did. If you read the manual, you will also see they highly recommend double wall stove pipe. My gut tells me that shouldn't make that big a difference either. Maybe you get away with it, maybe you don't. Maybe the system doesn't perform ideally, maybe you don't notice the difference. It wasn't worth the chance to me.

Now, if that 6" pipe were already installed and sealed up in a chase, I would hook the stove up and see how it worked.

Hi SaW,

Thanks--I appreciate your reality check, and agree with all that you said. Agreed that I would be unlikely to swap chimneys unless there were gross performance problems--backpuffing, difficult lighting, etc. At this point I'm thinking that unlikely, so, with the information I have now, my choice is between: 6" with a small chance of grossly bad performance and ongoing uncertainty as to whether the stove is performing as it should, and 8" for another $1,200 but with no worry of swapout or nagging performance questions.

I'm uncertain. So far I've done everything high quality with this house.

On the plus side, I have time to decide, and in the meantime can get some wood seasoning. ;-) And I found investigating this educational and fun.

Thanks to all!

 

[hack]

Did either of you guys end up going with the King and a 6" flue? If so, how did it turn out?

 

[BrowningBAR]

Suggesting a 2.8 cu ft stove for a home that is over 3,300 sq ft is bad advice unless we are talking about a very mild climate.

 

[jeff_t]

Did either of you guys end up going with the King and a 6" flue? If so, how did it turn out?

OP hasn't been around in a year, the other one for almost two. I would be interested to know, as well, but...

 

[wkpoor]

An insualted 35' chimney will draw so hard you could probably burn the king on a 4" pipe. I had a stove some yrs ago with an 8" outlet hooked to my 6" chimney and still had to damper it down.

 

[HotCoals]

The king on a 6 might have a problem when you open the door.
But even then if you open it slow I doubt if it will be much of a issue.