Chimney Height Question

[SummerTyme]

Hi everyone – I’m a new member to the forums. However, I have been lurking for a few months and learning much.

I have just had a new Napoleon 1450 installed. I have a concern about my chimney height. The current chimney height is 14 ft. from top of stove to top of outside chimney just below the chimney cap. It goes straight up out of the roof from the stove with no angles. I have triple-wall DuraPlus chimney pipe outside and single wall black stove pipe inside. My chimney cap is a VacuStack because I had backdrafting issues with my old stove when the winds were strong out of the southwest. I had an old 1999 Englander with a small 16” x 16” firebox. It was not EPA technology, just basically a box lined with firebrick. My chimney comes out of the single story part of the house and the second story part of the house is 11 ft. away from the chimney. The chimney is taller than the upper story part of the house except for the peak of the upper story where it is about a foot lower. Everything was fine with drafting until very strong (+40 mph) winds from the southwest which is the direction where the chimney is not taller than the peak of the upper story. In high southwest winds with the old stove, as long as I kept a very hot fire and chimney hot along with adding the VacuStack chimney cap the backdrafting and filling the house with smoke was very minimal.

Ok, so I have this new stove installed and I asked the Napoleon certified installer if I should add length to the outside chimney. I was thinking to add another 2 ft to help with draft and help prevent backdrafting and smoking up the house. (BTW, I am not pleased with the installer as he was very arrogant and when I asked questions he told me I was in information overload.) Anyway, the installer tells me that he doesn’t recommend adding 2 more feet to the chimney because I have the VacuStack chimney cap and that could cause too much draft and overfire the stove. He said I should just see what happens this coming winter. Ok, so that sounds reasonable, but if I do get backdrafting problems I sure don’t want to be up on the roof in the winter trying to install 2 more foot of chimney. And the installer said he would not install more chimney until next spring – if it was necessary. But, if I am going to have slow burns through the night with the stove draft control shut down to low so I can get some sleep at night and not have to get up every 2 hrs to load wood like I did with the old stove, that means the chimney will not be very hot and my thinking is that with high southwest winds I may get backdrafting during the night and wake up to a house full of smoke. Ugh!

So here is my dilemma, do I add 2 ft to chimney height now and risk overfiring the stove because of too much draft or wait until I burn this winter to see what happens? I had read on this forum that some Napoleons are easy to overfire, so I do want to prevent that problem if having too much chimney length combined with the VacuStack cap would cause an overfire. However, if I do have backdrafting problems in high southwest winds with the new Napoleon it means I will not be able to burn during those times, which would suck. Asking for opinions here because I am bouncing back and forth on this issue. And with the installer being so arrogant, I hate to bug him again and be made to sound stupid.

I have posted pics of my outside chimney.

Thanks

 

[begreen]

I don't think there is a chance of overfiring with an additional 2 ft. of pipe. 16ft is what Napoleon tested the stove with and what I would want. The 1450 needs good draft to perform well. That said, this is going to be a tall outside stack. The guy wires don't give me a lot of confidence, but perhaps the photos are not showing the turnbuckles well. There are tighteners on each wire, correct? Personally I would like to see a rigid brace at the 5ft level of this pipe, but that could just be me.

PS: Is there galvanized pipe mixed with stainless on the chimney?

 

[bholler]

I agree with bg id do the solid brace but i think you still need the guywires to. And you should not over draft with that height you should be fine to add a bit. Especially if it means you can loose that vacustack. i think they are a real pita to clean.

 

[begreen]

Agreed, I didn't mean to lose the guywires, but to augment them. The pipe needs to be braced every 5 ft above the roof exit.

 

[bholler]

Agreed, I didn't mean to lose the guywires, but to augment them. The pipe needs to be braced every 5 ft above the roof exit.

Ok i misunderstood that

 

[SummerTyme]

Agreed, I didn't mean to lose the guywires, but to augment them. The pipe needs to be braced every 5 ft above the roof exit.

Thank you for the responses.

Regarding the guy wires. I know it is hard to see in the pics, but there are guy wires at the top that go to all 4 corners. And there are guy wires in the middle just above the stainless steel portion of the first section of pipe that go to all 4 corners. So the pipe is supported by guy wires both in the middle and at the top. I did not want to put the rigid braces on because I just had a new roof installed on the lower part of the house and I don't want to put holes in the roof. I've had so many issues with the roof leaking I didn't want more holes to worry about. This chimney has been secured with these type guy wires since 1999 and I do get high straight line winds out here (+60 mph) and have never had an issue with the chimney not being secured or moving. The only issue I ever had was the chimney cap blowing off, so it is also wired down to the chimney pipe now.

Yes, there are galvanized outside wall and stainless steel outside wall sections, but inside is the same. Just in the older days the pipe was made with galvanized outside wall. Originally, the chimney was shorter but after about 5 years of burning and having backdrafting issues with the old stove I added another 3 ft section (stainless steel section) and the VacuStack cap.

Also, this is the second VacuStack cap I've had on the chimney in the time I've been heating with a wood burner. The one in the pic is new this year, but I did not find that cleaning the old one was all that difficult. Its just that I had chicken wire wrapped around it because of birds getting in the chimney. So this year I splurged and got a new cap with 1" squared spaced stainless steel screen specially made for the VacuStack cap.

 

[SummerTyme]

Oh, one more thing I should mention. As you can see from the one pic, the chimney comes up out of the roof at an angle or is leaning, if you can see that. Well, I will admit it was my bad along with my father when we originally installed the chimney we didn't allow for the roof pitch and didn't cut the hole right, so have a lean to the chimney. Another concern with adding more chimney length would be that the lean would be ever greater. The installer did mention that could be an issue with having too much lean on the chimney. To fix that problem would require a complete tear down of the chimney and recutting the hole which at this stage since I've had the new roof installed would be a real pain. So far, the lean has not caused an issue with the current height.

 

[begreen]

Sounds like another father/son project may be coming up soon. Given what you have learned, would you still have the stove in the same location or would you have located the stove closer to the center of the house?

 

[SummerTyme]

Sounds like another father/son project may be coming up soon. Given what you have learned, would you still have the stove in the same location or would you have located the stove closer to the center of the house?

Well, let's make that a father/daughter thing. lol - I'm a petite female. But, unfortunately my father is no longer earthbound. But, heck I don't have a problem getting up on the roof. I have taken the chimney down by myself to clean it. But, it has already been down and cleaned and installed back up with new guy wires. I sure don't want to tackle that again this year. If I had known what I know now I would have done it when the roofers were up there. As they say, hindsight is always 20/20.

Yes, I would still install the stove in the same location because that is about the only place it can go with my house layout. May have put it over another foot towards the edge of the roof, though.

I still have the question in my mind that if I add another 2 ft of outside chimney with the lean of the chimney is that going to cause a problem? Because, as you say, that's going to be a long outside chimney height and more lean to boot.

 

[begreen]

Sorry about your dad's passing SummerTyme. Your concerns are justified. Errors are amplified when at the end of a lever, ie: a tall pipe. We had a fellow here a couple years back that had the same Napoleon on a short chimney. He cursed and blamed the stove. We suggested adding pipe and finally he relented. The next post was that the stove was working fine.

 

[SummerTyme]

Sorry about your dad's passing SummerTyme. Your concerns are justified. Errors are amplified when at the end of a lever, ie: a tall pipe. We had a fellow here a couple years back that had the same Napoleon on a short chimney. He cursed and blamed the stove. We suggested adding pipe and finally he relented. The next post was that the stove was working fine.

Thank you Begreen. You have been very helpful.

This is a new learning experience for me with getting my first EPA stove. Its like having a 1960's car and upgrading to a 2014 car with all the new technology.

I have another question about my chimney setup. With the old stove I had a barometric damper installed on the inside pipe. I have read on this forum that having one of those is not a good thing. I don't understand why? How is it that they are detrimental? And I am wondering if having the barometric damper on the old stove could have been part of the problem with the backdrafting. With the new Napoleon there is no barometric damper and there is no key damper. Just straight pipe up to the ceiling connection box.

And it is my understanding (please correct me if I'm wrong) that the VacuStack cap will create a partial vacuum around the top of the chimney thus causing flue gasses to flow up and out and cutting down on backdrafting. When I put the VacuStack on my old stove setup it did help the backdrafting alot. Although, as I have stated before, I did get some backdrafting in very high southwest winds unless I had the chimney thermometer reading over 450 degrees which meant I had to keep the stove blazing during high winds. (The southwest winds come in towards the peak of the house and push the smoke towards the house which is 11 feet away from the chimney.)

 

[begreen]

Some EPA stoves work better on shorter chimneys than others. My theory is that this is in part due to longer and more circuitous secondary manifold design. The idea is to preheat the secondary air by running it inside the firebox for a distance. Problem is that if that secondary air path is long and has 2-3 90 deg turns in it, there is going to need to be stronger draft to pull the air through. The Napoleon is a good stove, but the secondary path is long. It wants good draft. I am certain you will not have an issue with too strong draft.

It sounds like wind at times is flowing with a downward pressure on the chimney. This is because chimney location is not great. That's why I asked if you had considered moving the stove. The vacustack cap should help, but it is a partial fix.

http://www.woodheat.org/wind-chimney.html

 

[SummerTyme]

BeGreen

Thank you for the link to the very informative article on wind effects on chimneys. I have read it and think I have a better understanding. I would say that the part in the middle section of the article that talks about installing in a single story of a two story house probably applies to my situation. Also the part that talks about strong winds causing a house to become depressurized probably applies also. My house is an old farm house over 100 yrs old with poor insulation (blown-in insulation that has settled) and leaky windows which I cover with plastic in winter, so the house is leaky and drafty. So my problem may be a combination of stove location, chimney height and leaky house.

I have read through my stove's manual and I can find no mention of minimum chimney height. Grrrrr It would be nice if Napoleon would put that spec in their manual. All the other specs listed, my stove is in compliance with. Even the height from bottom stove pedestal to ceiling is the 84" specified in the manual. And from bottom of flue collar to ceiling is 54". I may have more than 14 ft chimney height from flue collar to top of chimney without including the cap. I measured the inside stove pipe and the outside chimney pipe from roof level to top and then estimated the part under the roof between roof and inside ceiling as 1 foot, but it could be a little more than that since I can't see it and I don't remember from long ago when it was installed in 1999. However, that still doesn't negate the fact that from the southwest angle on outside of house that the chimney is not taller than the second story roof peak. But, installation info says that that the chimney needs to be 2 ft higher than 10 ft from nearest roof line, so I thought since it was 11 foot to nearest roof line I'd be ok.

Since I can't relocate the stove, I'm going to have to find a way to deal with this. I looked at the diagram of how the secondaries exhaust on my stove and it does look like its a long path with 3 90 degree turns in the path before the gasses flow up the stove pipe.

My installer was concerned about too much draft by adding more chimney length because he said the VacuStack cap would aid in drafting. Although, I'm not so sure I have that much confidence in him since he installed the firebrick wrong in the stove and I had to reinstall it according to the manual's instructions. After he installed the firebrick there was one firebrick left over and he said the manufacturer had sent an extra. Well, after I reinstalled the firebrick there was not one left over.

I think I have gained much more knowledge off this forum than I ever could talking to the installer. Thank you so much.

 

[begreen]

I'd try the stove with the current chimney. With the vacu-stack cap it may work out ok. Worth a try. As long as your wood supply is fully seasoned there is a good chance it's going to work ok, particularly as temperatures get colder and drop below freezing. Keep us posted and don't hesitate to ask questions. Burning in an EPA stove is different. There will be a learning curve, but in the end you should have a longer, cleaner, warmer burn and use less wood.

 

[SummerTyme]

Burning in an EPA stove is different. There will be a learning curve, but in the end you should have a longer, cleaner, warmer burn and use less wood.

Yes, I know this stove is going to be an entirely new experience. I'm so used to my old stove that I've used for 15 yrs. All I had to do with it was open the door and through wood in about every two hours. It didn't have any kind of draft controls on the stove, so the burn was controlled by how much wood I loaded. I have read many posts on this forum by people who are new to EPA stoves and they have vented their frustrations. I'm sure that I will have many frustrations myself. But, I think with all the reading I have done on this forum I am more knowledgeable about how these stoves work and hopefully will be able to figure out the operation of my stove before I pull all my hair out. lol You can be assured that I will continue to read this forum to gain knowledge. Its the best on the net, in my opinion. And you, Begreen get 5 gold stars for your help.

My wood is seasoned pretty well. I am using about 70% ash, some oak, hickory, and maple. I moisture tested some that I recently split into smaller pieces to use for my breaking in period and most was under 20%.

I am still not sure about adding or not adding 2 more feet of chimney. However, this afternoon I took another picture of my chimney. This time instead of standing on the ground to take the pic, I climbed up a ladder to be at roof level and it presents an entirely different view of the lack of height above the upper story roof. I have posted it so you can see it too. I think now that I can see the problem is that I am not higher than the upper story roof in the west, southwest direction. Being that the chimney is short somewhat and that the manufacturer recommends 16 ft chimney height, perhaps I should add the length. It will be a pain to do so, but I'd rather be doing it while its warm than in the middle of winter. And maybe being 11 feet away from the upper story roof isn't enough in my situation.

I wish there was a way to shut these EPA stove drafts down entirely, I looked at my draft control from the underside of the stove and when the control is shut all the way, the primary intake is still open about 1/2" and the secondary intake is still open about an inch. So, if I do get an overfire from too much draft how am I going to shut it down? From reading this forum I do understand that EPA stoves are made this way to comply with the EPA regulations.

 

[SummerTyme]

oops forgot the pic

 

[Woody Stover]

Too much draft is usually the result of having a very tall stack. I think your draft will be within reason, given the stove and chimney height.

 

[SummerTyme]

Too much draft is usually the result of having a very tall stack. I think your draft will be within reason, given the stove and chimney height.

Thank you Woody for your thoughts.

I have bounced back and forth on adding more chimney height but after reviewing everyone's thoughts, I think that I'm going to just leave the chimney as is and see what happens this winter. I'm thinking that this new stove is probably going to draft differently than my old one, so I might as well just see what happens when I get the high winds. I guess if the high winds do become an issue with the new stove, I will just not burn when the weatherman says we will be getting high southwest winds and then next summer add 2 more feet of chimney to see if that helps. I do have two wall ventless propane heaters in the house and also a couple oil filled electric heaters for backup, so I won't freeze.

Thanks everyone for you input. You guys are great.

 

[begreen]

What will be important is how the stove burns when the winds are calm and it's 40F or below outside. If you are getting good secondary combustion and burn times then you are pretty well set for winter. I would add a rigid brace at the 5 ft level regardless.

 

[Woody Stover]

What will be important is how the stove burns when the winds are calm and it's 40F or below outside.

I will just not burn when the weatherman says we will be getting high southwest winds

If we've got a southwest wind in these parts, it usually isn't too cold out anyway; When it's from the north is when you need that stove going to keep Old Man Winter at bay.

 

[SummerTyme]

If we've got a southwest wind in these parts, it usually isn't too cold out anyway; When it's from the north is when you need that stove going to keep Old Man Winter at bay.

Unfortunately, that is not true in my neck of the woods. I am southwest of Lake Erie and here we get very high winds from the southwest, west, northwest and northeast even when the temps are below 20 degrees F. Sometimes those winds can get in excess of 60 mph, but it is very normal to have 30 to 40 mph winds here year rounnd. The bad storms that come out of the midwest and head this direction usually come with high southwest or west winds. The northeastern storms coming off the lake are real killers. And I am located out in the middle of flat open fields so nothing to block the winds. Last winter was an unusually cold winter here and had many days below zero at night with high winds. During the coldest time we had wind chills reaching -50. The north winds didn't bother the old stove with backdrafting, just the southwest to west winds. I guess because the stove is located on the west side of the house with the second story to the east. Spent many a night up all night stoking the fire to keep the chimney hot to prevent filling the house up with smoke. That was one of the reasons for wanting a new stove, but I don't know if the new stove is going to be any better with that type of weather.

BTW - last winter was a bear here. Seems like all I did all winter long was move snow. Some of those snow drifts were 4 to 5 feet tall in my very long driveway. I sure hope this winter isn't like last winter, but we have had an unusually cool summer this year so if that pattern continues we will probably have another bear of a winter. Ugh!

 

[begreen]

Yes, last winter in your area was a bear. Are you handling this on your own? The new stove should hold a fire longer. Do you have good smoke detectors and CO monitor installed?

 

[SummerTyme]

Yes, last winter in your area was a bear. Are you handling this on your own? The new stove should hold a fire longer. Do you have good smoke detectors and CO monitor installed?

Yes, on my own. The work keeps me fit. Its lovely out in the boonies - so peaceful.

My reason for buying the new stove was to be able to sleep longer during the night instead of having to get up every two hours. Been doing that for too many years - it gets old.

My biggest concerns with this new EPA stove is over firing (I have read this can be a problem for newbies to EPA stoves) and the back drafting issue which was the reason for this thread. I will admit that I am a little nervous but, as long I don't burn the house down in the learning process, I think I will like the stove. I do like the fact it can take a bigger log than my old one. Most firewood sellers around here split to 17 or 18 inches in length. I usually split my own but sometimes have to buy a load. With the old stove, putting more than a 15 inch log was crowding it. I also like the fact with this Napoleon I can load either north/south or east/west. One of the reasons I bought the Napoleon was because of the square firebox - more versatility.

Yes, have both smoke and CO detectors. Always put new batteries in at the time I start using the wood burner.

 

[SummerTyme]

New Question regarding over firing.

I just checked out my draft control from the underside of the stove. When the draft is shut all the way my primary intake is still open about an inch and my secondary intake is still open about 2 inches. That seems like a large opening on the secondary intake for the control to be all the way shut. I am wondering, if I do have an issue with the secondaries getting out of control, why couldn't I duct tape a piece of flashing over the secondary intake to take it down to only an inch opening when damper control is set all the way to low? Would that help or am I asking for problems?

My other question is: What if a person was to shut down the secondary intake completely on the low setting by taping flashing over the 2 inch gap.and just use the primary draft to do the work. Would that be detrimental to the stove? Yes, I know it would negate the EPA regulations and probably shut down the secondaries completely on low, but would the stove still work with just the primary burn intake? I'm not saying I'm going to do this, but am curious as to how doing that would effect the stove and the burn. Yes, I'm sure I would be putting out more smoke particulates, but out here no one is going to be breathing those gasses except me. And I have been breathing those gasses for 15 yrs. lol I really don't think I've inhaled that much pollutants since I'm inside most of the time during the cold staying cozy and the wind blows the smoke away.

 

[begreen]

Overfiring is not common. Some folks never experience it. Here are a few tips to avoid seeing this problem.
1) get a good stovetop thermometer. Condar makes a good one. Place it on the stove body, below the trivet.
2) avoid loading small splits (1-3") except for starting and as filler pieces between larger splits.
3) don't burn pure construction scraps, mix with cordwood if you are burning them
4) let the coal bed burn down before adding more wood. If you want to hurry this, put only one or two small splits on the coal bed and open up the air supply 50% or full
5) Don't run the stove with the air wide open except at startup or to get a fresh reload going. You will get more heat by closing down the air until the primary fire gets lazy and secondary combustion above the wood takes off

Don't modify the stove intakes, Particularly as you are learning the stove. The stove is a finely tuned and balanced system. Reducing secondary air will reduce efficient burning of unburnt wood gases. That means more smoke, more pollution, and less heat. Give yourself a full season to learn the stove well. With the shorter chimney it will perform differently in mild weather than in cold. Wood moisture will also dramatically affect its performance.