Unconventional BK stove install

[Woody Stoveman]

Hello All,

I have been doing a lot of research and spinning my gourd for some time now. I need some help to get a consensus on my BK project. Unfortunately, I live in a small town with little help and expertise. I am mostly curious if anyone has tried my configuration idea vs. theorizing about the idea to know what they learned from their experience. I’ll define my project below.

I have a fireplace, and I know what you’re thinking…”here we go”. The fireplace is brick and extends from the floor to the ceiling. I want to install a BKE40, but I would prefer to not make a penetration through my roof. I read the installation manual to determine my options (see attached). I have room on my current hearth for the stove to sit, and I’ll need floor protection in front of the heath to meet code. However, I am stuck on the stovepipe requirements. Per the manual, I need 36 in. of vertical pipe from the stove outlet before I can install a 90* elbow. After the elbow, the stovepipe would run about 2 ft horizontally through the face of the fireplace (I.e. brick) then connect to an insulated flex liner. The flex liner would run from horizontal to vertical to the brick chimney outlet (I.e. it would be equivalent to a horizontal run, then a 90* elbow, then a vertical run).

Interestingly enough, page 14 of the installation manual has an example calculation for this exact scenario.

My brick chimney is 15 ft tall. With the stove on the hearth, the stove outlet is 4.5 ft tall from the base of the brick chimney. This means there is 10.5 ft of height in the brick chimney from stove outlet to the brick chimney outlet. Given the values included in the manual, I have come to the below calculation:

Height of stove pipe needed above brick chimney = 15 ft (minimum chimney height at my elevation) + 4 ft (2, 90* elbows) + 4 ft (2-ft horizontal run. I.e. 2:1) - 10.5 ft (brick chimney height above stove outlet)
= 12.5 ft

If my calc is correct, the pipe outlet would be 12.5 ft tall from the top of the brick chimney or 27.5 ft tall from the ground and seemly excessively tall.

I researched to find a way to decrease the pipe height requirements and came across the ENERVEX draft inducer fan that can be installed at the stovepipe outlet . I know you guys are familiar with this item because I have seen it discussed in other threads.

The idea is to use this fan at the top of my brick chimney and eliminate the extra 12.5 ft of stove pipe required to maintain a proper draft. If this configuration works, the tradeoff is my stove will have difficulty or not draft at all without the fan. I haven’t taken a deep dive into the power requirements of the fan but they claim it “uses power equivalent to a lightbulb”.

I know what you’re going to ask me, (1) why not just use an insert and (2) why avoid the roof penetration.

(1) The house is technically 2,600 sqft, but 75% of it is vaulted ceilings. There are 30+ windows through the house with large old dual pane aluminum windows. Therefore, I estimate the space to heat is approximately a 3,000-sqft equivalent. I looked at the peak day therm usage during the winter from the furnace. I converted it to BTUs and divided it by 24 hours to get average peak day BTUs/hr of the furnace. The maximum BTUs/hr of the BKE40 surpassed the average peak day furnace BTUs/hr by at least 10,000 BTUs/hr. This is how I am justifying the BKE40. I assume I will run it at about 75% all day. I have found plenty of inserts that provide ample BTUs to heat the house, but as you all know, you don’t get a BKE40 to go 0-60 mph in 3 seconds. I want the BKE40 for: long slow burns to decrease the number of loads/day, a deep firebox to decrease the ash maintenance, an ash drawer for even less maintenance, no annoying blower, and an overall more efficient stove. I want this stove to replace my furnace in the winter, so I can kick out the PG&E bank robbers.

(2) Simple. Roofs are better with less holes.

I would greatly appreciate any thoughts you guys have regarding the project and my questions. Again, I would love to hear if anyone has attempted what I’m trying to do. I love burning wood and aspire to watch the ashes of my previous heating bills draft properly out of the stovepipe and sink into the dirt where they belong as tree food for the next burn.

Cheers,
- Woody

 

[begreen]

The KE40 is a good choice but trying to avoid a straight up flue through the roof is not. Done right, there is no need to worry about this.

 

[kborndale]

A 15 foot chimney is already at the minimum height before you put the 90s in it which basically makes it shorter. Any competent installer can go straight up and thru the roof without issues. Keep it simple, I do not recommend any sort of fan to increase draft. I would think that would also make it quite difficult to sweep the chimney.

 

[Todd]

I would look into a different stove that rear vents if you want to stick to venting through your fireplace. Maybe a Woodstock Ideal Steel or Progress Hybrid?

 

[EbS-P]

What size is the current flue? An 8” insulated liners needs 10” ID minimum.

Is this fireplace the best location in the house for a stove?

assume I will run it at about 75% all day.

Did you do the wood consumption math here. How much wood since stacked right now?

Heatpump and a big insert like the England’s 500i or the buck 91 would be my choice.

 

[begreen]

Yes, there are definitely large stove alternatives that will work on a 6" flue. If the stove will be pushed hard for heat a lot of the time, the catalytic advantage diminishes. They shine the best for low and slow burning. If a heat pump will be preferred for shoulder season heating then an easy breathing, hybrid or non-cat with a 6" flue may be preferred.

 

[Highbeam]

If you insist on keeping and using that brick masonry thing then it is far too short for the king. With all those vaulted ceilings your roof must be tall so I have to think you can find a better place for the stove and maybe leave the fireplace as is. I knocked down a masonry chimney and would much rather deal with the pipe penetration in the roof than the often leaking masonry chimney flashing attempts. It was nice to knock down that chimney before an earthquake did it for me!

If you still insist on keeping that pile of rock chimney then I would consider the Woodstock PH rear vented. It's a bit smaller at 3.2 cubic feet but is built for a hearth install such as this. Long burns, high output, high efficiency, low emissions, 6" stack.

On edit: Woops, I mixed up the PH and the IS. The PH is smaller at just 2.8 cubes. I would recommend the IS. https://www.woodstove.com/ideal-steel-hybrid-wood-stove Bonus points, it's only $2000.

but I guess both would work.

 

[begreen]

Agreed. As kborndale noted, from the PH manual:
The recommended minimum chimney height is 15 feet from the flue collar of the stove to the top of the chimney . This includes connector pipe and chimney pipe.

 

[Woody Stoveman]

What size is the current flue? An 8” insulated liners needs 10” ID minimum.

Is this fireplace the best location in the house for a stove?

Did you do the wood consumption math here. How much wood since stacked right now?

Heatpump and a big insert like the England’s 500i or the buck 91 would be my choice.

The current flue is 8”. I think you mean 10” O.D. vs. I.D. but I get what you’re insinuating….a big hole.

Unfortunately, even with the vaulted ceilings, the fireplace is the best location for the stove. It’s as if they designed the place for wood heat.

You bring up a very good point about wood consumption, which I am going to post to the main thread about after this post.

 

[Woody Stoveman]

Hi All,

First, thank you to everyone for your responses! Each response provided very good information! This community is awesome. Also, apologies for the delayed response. I became caught up in multiple deadlines all at once 🫠

Second, hat tip to EbS-P! This may not have been your intention, but you helped me stumble upon solid gold buried in the deep in clenches of the government. I will explain. First, thank you for recommending the Buck 91. It was during my research of the Buck 91 that I stumbled upon this mysterious treasure chest known as the Non-CBI Certification Test Reports. It was when I opened this chest that I discovered the solid gold within, which is all the testing data used to certify stoves for performance and emission tests.

Being that you are all pros here, you are probably yawning at a newb who just discovered his first test report. However, I was shocked at the level of data included in these reports and that all stoves seem to require these tests for certification. Some reports are formatted better than others, but at least the testing procedures appear to be consistent. This means I can use the results to compare stoves based on performance level and make a more informed decision. I had always wondered how the stove companies determined their heating capacities and performance, and these were the answer. I know they use crib wood for testing, but at least it is consistent.

What I don’t understand is why out of discussing different stoves with multiple installers, none of them have ever mentioned the test reports.

With the test reports, I have been able to approximate and compare wood consumption, efficiency, air intake settings, determine efficiency of a flue blower, etc. across all stoves to determine quantifiable tradeoffs between the stoves. I also find it somewhat appalling but comical that some of these companies “hide” these reports, and others (like the Buck 91) “boast” these reports. But it’s American so of course we would boast 💪

If anyone asks me about a stove, I will tell them to read the test reports.

My next investigation will be to calculate the actual chimney height required given atmospheric data from my area and the flue temps.

I’ll work on responding to everyone’s post individually.

 

[Woody Stoveman]

Yes, there are definitely large stove alternatives that will work on a 6" flue. If the stove will be pushed hard for heat a lot of the time, the catalytic advantage diminishes. They shine the best for low and slow burning. If a heat pump will be preferred for shoulder season heating then an easy breathing, hybrid or non-cat with a 6" flue may be preferred.

I assume the catalytic advantage diminishes under higher heat burns because you get a more complete burn at high heats and thus there is less remaining particulate to re-burn.

You make a good point about this. This is why I am trying to oversize my stove and run it at the lowest setting to get the slowest burn but meet the needed BTUs

I have considered the Regency F5200 but it seemed to have a much higher consumption/BTU rate. This is where the BK seems to shine. The tradeoff I’m seeing is the BK just won’t get as hot.

 

[Woody Stoveman]

Agreed. As kborndale noted, from the PH manual:
The recommended minimum chimney height is 15 feet from the flue collar of the stove to the top of the chimney . This includes connector pipe and chimney pipe.

I will have to investigate this. The BK manual also mentions a 15 ft minimum but requires you to factor in for non-vertical pipe. What I have noticed, and this makes sense, is the hotter the flue temps, the shorter the chimney requirements. This makes sense given hotter air needs less pipe to rise, but higher flue temps means less efficient or higher consumption rate stove.

 

[Tron]

The tradeoff I’m seeing is the BK just won’t get as hot.

This is just a guess, but I suppose that isn't really an issue for anyone. We have people in AK running BK's, and while they may need to run WOT on very cold nights, I don't think anyone has ever mentioned that the maximum heat output is way too low.
And even if you have to run supplemental heat in extreme weather, I would assume that the times where the BK shines are way longer and more often than those extremes.

 

[kborndale]

BKs can get just as hot as other stoves, just when you run them at those temps you don't get the longer burn times. So if you have to run them at high heat all the time you loose the main advantage and reason they cost more, the ability to run low and slow.

 

[begreen]

BKs can get just as hot as other stoves, just when you run them at those temps you don't get the longer burn times. So if you have to run them at high heat all the time you loose the main advantage and reason they cost more, the ability to run low and slow.

I thought that the thermostat limited the top end on these stoves. I seem to recall Ashful stating that even when wide open, the thermostat will kick in and prevent it from overfiring.

 

[kborndale]

I thought that the thermostat limited the top end on these stoves. I seem to recall Ashful stating that even when wide open, the thermostat will kick in and prevent it from overfiring.

I was talking about running hot like you would when it's 10 degrees out, not hot enough to that the stove is over firing.

 

[Highbeam]

I thought that the thermostat limited the top end on these stoves. I seem to recall Ashful stating that even when wide open, the thermostat will kick in and prevent it from overfiring.

Correct. The theory is that the maximum temperature as limited by the BK thermostat is the same as the highest safe temperature any stove should be run. For example, both stoves of the same size and construction make the same output at 800 whether BK cat or noncat.

The debby downers might say that the BK thermostat caps max stove temperature at 600 compared to a noncat that can go to 1000.

Who knows but @Tron is correct. If you are running a BK wide open then you made a mistake in sizing or you somehow are dealing with a short term need to warm up a cold house. These stoves, all stoves, are happier keeping a warm house warm which is much easier with 30 hour max burn times.