Chimney Size Too Small for BKK?

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Dr. Richards

Member
Feb 22, 2012
30
Central ME
I'm looking into purchasing a BKK to replace my current woodstove but have concerns about my chimney size. My current setup is an oil furnace and and Englander 24-ACD (both 6" flue) into my interior chimney in the basement. Chimney height is about 25-26'. Local dealer said the interior area of my chimney (6.75" x 6.75" = 45 sq. in.) should not be less than the combined area of the flue size of any appliances, so with with two 6" flues this is (3x3x3.14) x 2 = 56 sq. in. According to this I am already too small but I have had no problems. However, if I go with a BKK w/8" flue I would now need 78 sq. in. (33 more sq. inches!!!) What should I do? I have read that reducing to 6" is not recommended. Also, because the internal dimensions of my chimney are 6.75" square, I can't make an 8" opening into it.
 
It sounds to me like you are going to need to be looking for a different large stove w/ a 6 inch flue.

Additionally, I'd add that venting multiple appliances into one flue, especially when combining 2 fuels, is pretty much a big no-no almost everywhere in the country (for a good reason btw).

However, maybe something like this? http://www.kent.ca/kbs/en/product.jsp?prdId=7160000&skuId=7160000&catalogId=1206

7160000_lg.jpg



pen
 
I have never heard of the flue size is oil burner + stove. 6-7" flue is really common and as you know oil burner and wood stove in that flue is also common.
 
Actually, in Maine last year they changed the law allowing two flues into same chimney even with different fuels. Most science shows no problems with this configuration and Maine finally figured it out. What about reducing flue on BKK to 6"? I really would like to use this stove if possible to heat my house (about 1900 sq.ft. not including basement).
 
Wow that's quite the POS (piece of steel), I like it, kinda more like what I had in mind, oh well.
 
From this document by Maine's Fire Marshal, RECOMMENDED STANDARDS for the INSTALLATION of WOODBURNING STOVES http://www.maine.gov/doc/initiatives/wood_to_energy/docs/woodstoves.pdf

The flue area should not be smaller than the largest
connector pipe plus 50% of the additional area of a second connector
entering the same flue.

Sounds like even if your chimney is pre-1998 you don't meet that requirement, assuming that is their standard for whatever "adequate draft" means to them.

pen
 
BK stoves are pretty draft sensitive due to their low flue temps. I was tempted to burn the King in my flue but decided against it and went with the Princess. If you decided to burn it in the flue you have I suspect you will have low burn issues and plenty of smoke spillage on reloads after the stove has burned down and the flue has cooled.
 
Good point rdust.

The manual for the Blaze King http://www.blazeking.com/PDF/manuals/en/wood/OM-KE PE E V1.10.pdf states DO NOT CONNECT THIS UNIT TO A CHIMNEY FLUE SERVING ANOTHER APPLIANCE. It's actually listed in the manual in all caps and bold.

It does say: NEVER USE A CHIMNEY CONNECTOR OR CHIMNEY FLUE SMALLER THAN THE STOVE EXHAUST, UNLESS APPROVED BY YOUR LOCAL INSPECTOR.

However, after seeing some of the things that local inspectors do, I'd be curious to know what basis they would use to ensure that your stove would operate properly on a smaller flue since BK doesn't recommend it.

Additionally, since blaze king doesn't give the "unless approved by your local inspector" statement with the line about serving two appliances on one flue, I wonder if Maine law would supersede the manual's definitions of a proper installation? Since I've seen this in other manuals, this could be an issue with other newer stove perhaps.

I think that would be a big investment to make in the event that that unit doesn't work properly, even if Maine were to approve it.

pen
 
Thanks for all the research. I also read the manual and am basically frustrated because I have a small chimney ("small chimney syndrome"). However, my ol' man says use a 6" connector, "it'll be fine". The BKVP suggested using a manometer and measuring draft (like I know how to do that). He suggested .04-.08 water column inches and if I got more he recommended a damper. ???????
 
Dr. Richards said:
Thanks for all the research. I also read the manual and am basically frustrated because I have a small chimney ("small chimney syndrome"). However, my ol' man says use a 6" connector, "it'll be fine". The BKVP suggested using a manometer and measuring draft (like I know how to do that). He suggested .04-.08 water column inches and if I got more he recommended a damper. ???????

If you are hellbent on trying it, do you have a buddy who works in HVAC? People who work on oil boilers in particular often have and know how to use a manometer and could help you there.

My question would still be if it's ok to ignore that line in the BK manual about having 2 appliances on one flue, or if you'd be forced into using a stove that doesn't have that line in its literature. Another thing to consider, even if Maine law says it is somehow OK, are all of the insurance companies on board with this? Many insurance companies ask if the installation is approved AND meets the requirements of the installation guide. You'd have to really have your t's crossed and i's dotted before you put down cash I'd say so that there aren't any surprises.

No way to add a class A chimney somewhere here huh? That certainly seems like the simplest solution that should guarantee the performance and safety of both appliances.

pen
 
pen said:
However, after seeing some of the things that local inspectors do, I'd be curious to know what basis they would use to ensure that your stove would operate properly on a smaller flue since BK doesn't recommend it.
pen

My guess is if the local inspector signs off it it BK is pretty much removing themselves from the deal so they're ok with someone doing that if approved by someone.

I have a feeling it would probably burn decent on a high burn but low burn would stall. I think ohlongarm and bogydave are both burning in 8" flues and have posted about having low burn issues.
 
Id find another place to vent the stove, is cost a problem or placement?
 
rdust said:
BK stoves are pretty draft sensitive due to their low flue temps. I was tempted to burn the King in my flue but decided against it and went with the Princess. If you decided to burn it in the flue you have I suspect you will have low burn issues and plenty of smoke spillage on reloads after the stove has burned down and the flue has cooled.

This is very true. I had around 12' of 8" pipe from the collar, straight up and double wall connector. It worked okay, but adding another 3' made a very noticeable difference.
 
Another chimney isn't an option. Another aspect I was wondering was: both the furnace and the woodstove would rarely be running at same time; the furnace would only run for my hot water and when the temps got cold enough that the woodstove couldn't keep up. I didn't know if that would make a difference. Also, if I MUST give up on this one, what would be the closest comparison to a BKK with a 6" flue and not hugely sacificing wood box size?
 
Have you considered the BK Princess? It's not the monster the King is, but it's still a very big stove and is probably second only to the King in burn time.

Blaze King should have never used 'Princess' as a name, the feminine name suggests a small stove, and it is not a small stove at all. They should have named the bigger one 'Emperor,' and the smaller one 'King.' Anyway- the Princess uses a 6" flue.
 
Some oil burners can be direct vented. Any chance you have looked to see if that is an option for yours?

The stove i mentioned at the top of this thread is the largest non-cat stove that I am aware of w/ a 6 inch flue collar.

pen
 
Gotta ask . . . since I am always quite curious . . . Central Maine means different things to different people . . . it could mean LA, Bath/Brunswick, Belfast/Camden, Augusta/Waterville or even Bangor . . . if you don't mind me asking . . . which town or city do you hail from . . . and no, I promise not to visit you unannounced.

Minor correction . . . the legislation regarding the two flues in one chimney was actually passed several years back when the oil prices first skyrocketed to over $4 per gallon. I'm honestly still not sure if I think it was a good idea and perfectly safe or if the existing NFPA code was written for a very good reason. What I am sure of though is that the main reason this law passed muster was that the legislators were very concerned with Mainiacs not being able to run the woodstove or pelletstove they had bought or dug out of the proverbial mothballs . . . and so the law was approved.

As Pen said . . . the only possible sticking point with the two flues issue could be with the insurance company. Some may have no issues . . . heck, some may never do an inspection or require anything from you. Other insurance companies may send their own inspector or refuse to carry you if you go against the national code. It really is a big question . . . and something you would want to address first.

Best choices . . . 1) Stick with the model you want and go with Class A (any reason you cannot or do not want to go out and up?), 2) go with a different model in the BK line up or another brand or 3) see if you cannot convert the oil boiler to a direct vent. If you elect to look at other stoves what is it that you most desire in a woodstove -- pure heating power or length of burn or both? I ask since at 1,900 square feet there are many, many stoves that could heat your home. At 1,800 square feet I can heat my two story Cape with the Jotul Oslo . . . but if you're also looking for very long burn times you might be better off sticking with the BKs or Woodstock line up.
 
firefighterjake said:
Gotta ask . . . since I am always quite curious . . . Central Maine means different things to different people . . . it could mean LA, Bath/Brunswick, Belfast/Camden, Augusta/Waterville or even Bangor . . . if you don't mind me asking . . . which town or city do you hail from . . . and no, I promise not to visit you unannounced.

Minor correction . . . the legislation regarding the two flues in one chimney was actually passed several years back when the oil prices first skyrocketed to over $4 per gallon. I'm honestly still not sure if I think it was a good idea and perfectly safe or if the existing NFPA code was written for a very good reason. What I am sure of though is that the main reason this law passed muster was that the legislators were very concerned with Mainiacs not being able to run the woodstove or pelletstove they had bought or dug out of the proverbial mothballs . . . and so the law was approved.

As Pen said . . . the only possible sticking point with the two flues issue could be with the insurance company. Some may have no issues . . . heck, some may never do an inspection or require anything from you. Other insurance companies may send their own inspector or refuse to carry you if you go against the national code. It really is a big question . . . and something you would want to address first.

Best choices . . . 1) Stick with the model you want and go with Class A (any reason you cannot or do not want to go out and up?), 2) go with a different model in the BK line up or another brand or 3) see if you cannot convert the oil boiler to a direct vent. If you elect to look at other stoves what is it that you most desire in a woodstove -- pure heating power or length of burn or both? I ask since at 1,900 square feet there are many, many stoves that could heat your home. At 1,800 square feet I can heat my two story Cape with the Jotul Oslo . . . but if you're also looking for very long burn times you might be better off sticking with the BKs or Woodstock line up.

I live in Madison, so I guess I'm in the "Waterville" crowd. I probably could direct vent my furnace or do a class A but don't really want to. So probably I will change my stove choice. When I bought this house the stove setup was the same and when I got insurance nobody visited (at least yet). My current stove (Englander 24-ACD) supposedly heats 2000 sq ft but I currently burn 500g of oil and 5 cord of wood each year for the last 3 years. So I am skeptical of the claims and want to go big. It's in my basement so I'm not worried about roasting us out.
 
pen said:
Some oil burners can be direct vented. Any chance you have looked to see if that is an option for yours?

The stove i mentioned at the top of this thread is the largest non-cat stove that I am aware of w/ a 6 inch flue collar.

pen

It's funny that you posted a Kent. The only Kent I have ever seen is at my mother in law's house and has been in the same spot for 23 years (used every year). Are they good? The link did not seem like it has very much information (cubic feet?) and the price seems kind of "cheap" comparatively.
 
Dr. Richards said:
pen said:
Some oil burners can be direct vented. Any chance you have looked to see if that is an option for yours?

The stove i mentioned at the top of this thread is the largest non-cat stove that I am aware of w/ a 6 inch flue collar.

pen

It's funny that you posted a Kent. The only Kent I have ever seen is at my mother in law's house and has been in the same spot for 23 years (used every year). Are they good? The link did not seem like it has very much information (cubic feet?) and the price seems kind of "cheap" comparatively.

Never burned one and really haven't seen much in the way of reviews on them. But for the money and size, if my 30 were to crap out I would be giving one a go.

pen
 
pen said:
Dr. Richards said:
pen said:
Some oil burners can be direct vented. Any chance you have looked to see if that is an option for yours?

The stove i mentioned at the top of this thread is the largest non-cat stove that I am aware of w/ a 6 inch flue collar.

pen

It's funny that you posted a Kent. The only Kent I have ever seen is at my mother in law's house and has been in the same spot for 23 years (used every year). Are they good? The link did not seem like it has very much information (cubic feet?) and the price seems kind of "cheap" comparatively.

Never burned one and really haven't seen much in the way of reviews on them. But for the money and size, if my 30 were to crap out I would be giving one a go.

pen

Oops, my mistake. That stove you linked is not a Kent (Kent is the buidling supply selling it), it is actually a JA Roby which is based in Quebec. Don't know anything about 'em.
 
Dr. Richards said:
firefighterjake said:
Gotta ask . . . since I am always quite curious . . . Central Maine means different things to different people . . . it could mean LA, Bath/Brunswick, Belfast/Camden, Augusta/Waterville or even Bangor . . . if you don't mind me asking . . . which town or city do you hail from . . . and no, I promise not to visit you unannounced.

Minor correction . . . the legislation regarding the two flues in one chimney was actually passed several years back when the oil prices first skyrocketed to over $4 per gallon. I'm honestly still not sure if I think it was a good idea and perfectly safe or if the existing NFPA code was written for a very good reason. What I am sure of though is that the main reason this law passed muster was that the legislators were very concerned with Mainiacs not being able to run the woodstove or pelletstove they had bought or dug out of the proverbial mothballs . . . and so the law was approved.

As Pen said . . . the only possible sticking point with the two flues issue could be with the insurance company. Some may have no issues . . . heck, some may never do an inspection or require anything from you. Other insurance companies may send their own inspector or refuse to carry you if you go against the national code. It really is a big question . . . and something you would want to address first.

Best choices . . . 1) Stick with the model you want and go with Class A (any reason you cannot or do not want to go out and up?), 2) go with a different model in the BK line up or another brand or 3) see if you cannot convert the oil boiler to a direct vent. If you elect to look at other stoves what is it that you most desire in a woodstove -- pure heating power or length of burn or both? I ask since at 1,900 square feet there are many, many stoves that could heat your home. At 1,800 square feet I can heat my two story Cape with the Jotul Oslo . . . but if you're also looking for very long burn times you might be better off sticking with the BKs or Woodstock line up.

I live in Madison, so I guess I'm in the "Waterville" crowd. I probably could direct vent my furnace or do a class A but don't really want to. So probably I will change my stove choice. When I bought this house the stove setup was the same and when I got insurance nobody visited (at least yet). My current stove (Englander 24-ACD) supposedly heats 2000 sq ft but I currently burn 500g of oil and 5 cord of wood each year for the last 3 years. So I am skeptical of the claims and want to go big. It's in my basement so I'm not worried about roasting us out.

Ah, we're practically neighbors then . . . well I'm in Unity . . . so it would be a haul to borrow a cup of sugar.

One thing I highly recommend is that you figure out your spacing needs and go at least one size larger . . . the specs for spacing are based on a set standard . . . companies don't always take into consideration the amount of insulation in a home, home lay-out, etc. . . . and if it's in a basement you more than likely will want to go one size larger anyways.

I assume you've already read up on the "perils" of basement installs . . . some folks report problems with heat loss in uninsulated basements, reverse stack situations, etc. I suspect you're pretty much committed to putting this stove in the basement, but if possible putting it where folks spend most of the time often makes more sense (unless the basement is a livable, used space) . . . the benefit to putting the stove in the living space when possible are many -- view of the fire (nice views and you know when to reload), more heat right in the area . . . OK, maybe just two benefits . . . if space is a premium many of the newer woodstoves also have fairly close clearances with the addition of heat shields (purchased or built).
 
firefighterjake said:
Dr. Richards said:
firefighterjake said:
Gotta ask . . . since I am always quite curious . . . Central Maine means different things to different people . . . it could mean LA, Bath/Brunswick, Belfast/Camden, Augusta/Waterville or even Bangor . . . if you don't mind me asking . . . which town or city do you hail from . . . and no, I promise not to visit you unannounced.

Minor correction . . . the legislation regarding the two flues in one chimney was actually passed several years back when the oil prices first skyrocketed to over $4 per gallon. I'm honestly still not sure if I think it was a good idea and perfectly safe or if the existing NFPA code was written for a very good reason. What I am sure of though is that the main reason this law passed muster was that the legislators were very concerned with Mainiacs not being able to run the woodstove or pelletstove they had bought or dug out of the proverbial mothballs . . . and so the law was approved.

As Pen said . . . the only possible sticking point with the two flues issue could be with the insurance company. Some may have no issues . . . heck, some may never do an inspection or require anything from you. Other insurance companies may send their own inspector or refuse to carry you if you go against the national code. It really is a big question . . . and something you would want to address first.

Best choices . . . 1) Stick with the model you want and go with Class A (any reason you cannot or do not want to go out and up?), 2) go with a different model in the BK line up or another brand or 3) see if you cannot convert the oil boiler to a direct vent. If you elect to look at other stoves what is it that you most desire in a woodstove -- pure heating power or length of burn or both? I ask since at 1,900 square feet there are many, many stoves that could heat your home. At 1,800 square feet I can heat my two story Cape with the Jotul Oslo . . . but if you're also looking for very long burn times you might be better off sticking with the BKs or Woodstock line up.

I live in Madison, so I guess I'm in the "Waterville" crowd. I probably could direct vent my furnace or do a class A but don't really want to. So probably I will change my stove choice. When I bought this house the stove setup was the same and when I got insurance nobody visited (at least yet). My current stove (Englander 24-ACD) supposedly heats 2000 sq ft but I currently burn 500g of oil and 5 cord of wood each year for the last 3 years. So I am skeptical of the claims and want to go big. It's in my basement so I'm not worried about roasting us out.

Ah, we're practically neighbors then . . . well I'm in Unity . . . so it would be a haul to borrow a cup of sugar.

One thing I highly recommend is that you figure out your spacing needs and go at least one size larger . . . the specs for spacing are based on a set standard . . . companies don't always take into consideration the amount of insulation in a home, home lay-out, etc. . . . and if it's in a basement you more than likely will want to go one size larger anyways.

I assume you've already read up on the "perils" of basement installs . . . some folks report problems with heat loss in uninsulated basements, reverse stack situations, etc. I suspect you're pretty much committed to putting this stove in the basement, but if possible putting it where folks spend most of the time often makes more sense (unless the basement is a livable, used space) . . . the benefit to putting the stove in the living space when possible are many -- view of the fire (nice views and you know when to reload), more heat right in the area . . . OK, maybe just two benefits . . . if space is a premium many of the newer woodstoves also have fairly close clearances with the addition of heat shields (purchased or built).
Yeah, I'm committed to the basment. I used to have one in the living room in my other house, this one already had one hooked up in the basement. Benefits also equal 2: heated basement and no dust in my living room. However, my basement is not insulated and that is something I am looking into having done this summer. In the future I would like to have a little "ambience" stove, but this one is pure utility.
 
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