Just bought and installed duravent dvl double wall. Elbows were around $42, 24" was about $75, and the 6' telescoping was about $100. The manual says the pipe will fit most stoves (which it did on the princess) otherwise you need a starter section. The 3 existing holes on my stove collar didn't line up so I drilled new ones to match the pipe. The manual has all the offset tables and run lengths. If you run a plumb bob and see how far off you are the manual will tell you what length to put in between elbows. To my knowledge you can't run double wall elbows back to back, there has to be a connector piece in between.
2016-17 Blaze King Performance Thread (Everything BK)
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It is my understanding that you need to keep your flue as warm as possible with the BKs for proper draft and reduced creosote build up. Thats the way I am going to roll as I am doing a complete new install straight up with the 15 ft minimum.
raypa
Member
So the double wall is to help maintain chimney temps to keep the draft on the BK...??
Deeje
New Member
The cat never goes inactive, but it's usually getting close by the time she's ready to load. Will try raking coals forward, thanks for that.
My wood is 25% mc ash, and I usually do have to keep the tstat at 75-100% (no numbers on this one!) to keep the house warm.
Yep. BK's are very efficient. As a result, flue temps run lower than most stoves. Your days of using single wall pipe to recoupe some of the wasted up the stack heat is about to end
Ashful
Minister of Fire
I can get a photo tonight. You need a stove collar adaptor, the double wall does not go directly into the stove.
https://www.rockfordchimneysupply.com/dbl-wall-blk-stove-pipe-adapter-sizes.php
Also, double wall interior pipe is known as close clearance pipe as you can be 6" to combustibles since the surface runs cooler. Another big one is that the inner wall is stainless steel so it will not need to be replaced. Thirdly, unlike snap lok single wall, the joints fit together tivhtl. Holes in your pipes kill draft and cool the exhaust.
Please be specific about whether this flue temp is internal or on the surface. I know you have double wall pipe so you have to use a probe meter and those temps are internal but the guy who you're talking to has never seen double wall pipe and has only ever measured and known surface temps which run half as high as internal temps. I bet @raypa would be more impressed to know the whole story and that single wall surface temps would only be 100-125, so cool that you would barely know it's running.
Having seen the results of running internal flue temps so ridiculously cold, I aim to maintain 400 or higher internal flue temps which would measure over 200 on the skin of single wall. Still much much lower than normal stoves.
raypa
Member
Yep. BK's are very efficient. As a result, flue temps run lower than most stoves. Your days of using single wall pipe to recoupe some of the wasted up the stack heat is about to end
OK. So, where to buy the double wall? I have not yet asked my stove dealer.
That's too high! You'll see better results if you get drier wood. <20% is imperative; I like to have it closer to 15%. You risk fouling the cat and getting excessive creosote buildup otherwise.
I wasn't able to hook my selkirk DSP directly to my Ashford. The outer layer of sheet metal on the DSP was super close to stretching over the stove collar, but just couldn't quite do it. I was a bit disappointed, but had to break down and buy an extra "DSP stove adapter" to make it work.
The whole chimney needs to stay above 212 or water will condense out and cause sticky creosote buildup. The BK stove very low burn rate requires double walled pipe stove to cap to assist in this endeavor.
Northlineexpress has a LOT of stove pipe. I like to look at their inventory just to see what's out there. Spend some time browsing, and you'll see a lot of products, and can probably start forming some ideas about how you might use them.
https://www.northlineexpress.com/6-inch-black-stove-pipe.html
raypa
Member
I have a 6x9 clay lined brick chimney that I was planning to continue to use. It's approximately 15' tall from the thimble to the top. This is all new to me with a catalytic burner.
I believe all modern EPA wood stoves using an existing masonry chimney need an insulated liner all the way to the cap to avoid creosote problems. They just don't send the BTUs up the stack like the old hearth/"fireplace" systems did. Terribly inefficient.
Oh no, most all allow use of a properly built and in good repair masonry chimney so long as the size is not too big.
Ah, see, now you have some folks claiming internal flue gas temperatures of 200 near the stove which means very low condensing temperatures inside the chimney. Especially given the extremely low flow rates through the bk design.
15% moisture content is still a lot of water to be boiled off. 50# fuel load means 7.5 lbs of water which is more than a gallon. That's like pouring a 12 pack of beer into the chimney! That's fine if the water stays in vapor and makes it out of the stack.
The stove and cat only see vapor so no big deal.
Question, I reloaded a real hot coal bed about a half hour ago, have t-stat set about 5 o'clock position, roaring fire glowing cat, but still seeing smoke out the stack, is this normal ??
Stove is a BK ULTRA, installed last winter, 32 ft. Stack..
Stove is a BK ULTRA, installed last winter, 32 ft. Stack..
Gforcefd
Member
Thank you for posting. I just went there and purchased my 29-40 inch telescoping DVL pipe and saved $40 instead of going to home depot. Hopefully it comes in without too much delay and I can rework my stove location for a better draft. 9dF this morning and I really wished my wood stove was going instead of my furnace. I did just upgrade from a mechanical thermostat on the furnace to a programmable so I am saving a little fuel.
kennyp2339
Minister of Fire
Sorry Highbeam but i'm a BK sinner and using 6 1/2ft of single from stove collar to ceiling support box, I'm going on the premise that I have an interior chimney so I should be fine (as with the last 3 seasons) I'm also moving to another property in time for next season, I'll use double wall on the new BK install.
Dieselhead
Minister of Fire
If you have a full firebox with a ripping fire going your most likely creating more smoke then the cat can process.
Whoops, must have confused you with another member. I don't think single wall is all bad, not ideal but depending on the rest of the chimney it can be fine. The bk manuals allow it.
So surface temps of 200 mean internal temps of 400 and is a good minimum in my experience. I do believe that some guys are going much lower which is possible to do with an active cat but there are risks!
I have been curious about this and wondered if this is what occurs. I am burning softwoods so when I load the box and throw in some pine splits with the load it takes off really fast. I was letting it burn for about 15 minutes like that and the stove was getting really hot with heavy smoke in the box and chimney, but now I will let it go for about 5 minutes until everything looks a little charred before engaging the cat and letting it burn on full air for another 5-10 minutes before I start cutting the air back. All I am seeing is pretty much steam - very little smoke from the cap.
The sweet spot (as others have suggested) definitely seems to be around the 3:00 to 3:30 position on my stove. I see an occasional rolling flame, but it mostly stays dark and cruises along. I leave the fan on low and it has kept the upper two floors around 71-74 degrees in freezing temperatures. My reloads (in morning and at night) are a bit hotter than I would like because the box is still about a 1/4-1/8th full of charred wood, but it makes for very easy reloads on a 12 hour cycle. Pretty sure that I would be getting 16 hour plus burns with this setting and that is with fir, pine, and a split or two of tamarack. Surprisingly, the wood that has lasted longer than the big fir splits is the fir limbwood that are about 3 inches or better in diameter. Those are usually still burning with what is left of the larger tamarack splits in my box when the fir and pine is gone. I just disperse the coals around the box and set the new wood on top instead of raking it forward as others suggest. With the softwood there does not seem to be any problem with excessive coals.
As soon as the cat probe reads active, engage the cat! You risk melting those bypass retainers if you run it longer than you have to. After engagement you can do the 20-30 minute high burn if you want.
I pretty much do this, but I try to let all the wood catch in the box? Guessing that does not really matter and it seems to catch well when the cat is engaged and I run it on high? Thanks. I think I am getting the hang of this thing now - just want to understand it a little better.
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