# Chimney maximum height?



## jschardine (Aug 8, 2006)

Hi.  I am looking to purchase a wood burning insert into my masonry fireplace.  I have a very open floorplan with a balcony, so I am looking for a fairly large stove.  The problem I have is that my chimney is very high and I need 34 ft of pipe for my liner.  Many manufactures (i.e. Avalon, etc) specify a maximum chimney height of 30 ft or 33 ft.  When the stove shop talked to Avalon, they were told that there is no guarantee that the stove will work about 33 ft, nor is there a guarantee that the stove will not be damaged by more than 33 ft.  I believe I also lose warranty service from the stove shop where I purchase the unit.

My questions are:

1.  Is the manufacture's maximum chimney height of a stove a real limit?

2.  What risks am I taking by installing an Avalon Olympic stove with 34 ft of pipe?

3.  Are there other models that will work with 34 ft of pipe?  I've pretty much ruled out VC and HearthStone products due to chimney height.  I'd prefer a non-catalytic stove that heats in the neighborhood of 2600-3200 square feet.

4.  Is there a maximum chimney height specified for Regency stoves?

5.  My only other choice at this particular shop is a Buck Model 80 or Buck Model 91, both of which are catalytic.  Buck specifies a 40 ft maximum chimney height.  However, the cost of the 8" pipe (opposed to 6"), as well as the catalytist are negatives to me.

6.  If Buck is one of my only options, how is the quality of the newer Buck stoves?  Are they decent stoves?

Thanks in advance.

John S.


----------



## MountainStoveGuy (Aug 8, 2006)

I have heard of installers putting in barometric dampers to control over draft situations, but i believe that is only with stove.  The risks are overdrafting and over fireing. Thats a heck of a chimney,


----------



## BrotherBart (Aug 8, 2006)

Curious about why they want stand behind the stove with a chimney that high.

Overdraft? If so, why not downsize the liner?


----------



## MountainStoveGuy (Aug 8, 2006)

Downsizing the liner will create a bottle neck, 6 inch pipe is almost half the volume of 8 inch, the unit would want to spill smoke, not to mention it would be a illeagle istallation. 
I would love a scientific answer to BB questions,


----------



## elkimmeg (Aug 8, 2006)

the height is figured fron the top of the stove flue collar not the floor of the existing  fireplace That alone can make up almost 3'


----------



## jschardine (Aug 8, 2006)

When I asked whether it could damage the stove, I was basically told by the stove salesperson that they couldn't guarantee anything.  The stove might not work, it might get damaged, efficiency might go down, etc.  Basically, I was told it was at my own risk whether I wanted to install the Avalon.


----------



## jschardine (Aug 8, 2006)

When I had the chimney swept, I asked them to give me the exact amount of pipe required.  This is where they came up with 34' of actual pipe.  Avalon says the Chimney must be no greater than 33' tall.


----------



## MountainStoveGuy (Aug 8, 2006)

Ohh it would work all right, it would work to well. You would have an excess of draft, which would burn the stove at temps that it is not designed to burn at. You cant control non cat stoves like you can cats, thats why you are finding cats in your chimney hight range. You can block off the air much better on a cat.


----------



## BrotherBart (Aug 8, 2006)

I ask the liner size question because I have been looking at a few years out when I replace the basement stove. Because of the kink in the tile liner I have a 5.5 inch liner inbound for installation. Not real worried about it for the F100 that is there now because the actual flue exit on the stove is five inches. They ship an increaser with the stove so that a six inch pipe will fit it.

Every single manufacturer I have queried has said a 5.5 will be fine with their stove. Ergo, if over draft is a problem for this monster chimney, why wouldn't decreasing the size of the pipe keep it from sucking the splits up the chimney? Since under drafting has to be the only reason for requiring the larger pipe.


----------



## MountainStoveGuy (Aug 8, 2006)

two reason, it would not pass inspection, and the house would not be insurable. They have to be installed to the the stove manufactures listing, period.  Now thats a technicality, any one want to speak up on the engineering side of it?


----------



## elkimmeg (Aug 8, 2006)

PE summit 3100 sqft heat area no listing for max chimney height

 cheapest option a direct connect of an 8" flue collar outlet appliance It will satisfy most cross-sectional code acccording to NFPA 211

 Answer to brother barts question: Remember the reason for putting a liner is to enhance draft by reducing the area from the manonry setup to 6" round.   this being so further reduction to 5.5 might increase the draft vollume

 Look at your plumbing to build pressure in the system the pipe is reduced Meaning more pressure and exit velosity expand that area and you have n less pressure and on exit velosity to speak of.    

If this were the case to control over draft a 6.5" liner would be better in this setup maybe 7"


----------



## mtarbert (Aug 8, 2006)

Greetings,
           Why not neck down the liner at the top any decent sheetmetal shop could fabricate a 7 1/2 inch piece to be attached to the 8 inch run......Just a thought.
          Mike


----------



## BrotherBart (Aug 8, 2006)

elkimmeg said:
			
		

> PE summit 3100 sqft heat area no listing for max chimney height
> 
> cheapest option a direct connect of an 8" flue collar outlet appliance It will satisfy most cross-sectional code acccording to NFPA 211
> 
> ...



Excellent point. Guess that is why I failed physics class.


----------



## elkimmeg (Aug 8, 2006)

because the liner would have to be stainless steel though a connector pipe would not.  Also code coverns  no reductions of the flue collar area  So what are tou purposing? please explain He is trying to slow or prevent over draft not reduction to enhance draft


----------



## webbie (Aug 8, 2006)

MountainStoveGuy said:
			
		

> I have heard of installers putting in barometric dampers to control over draft situations, but i believe that is only with stove.  The risks are overdrafting and over fireing. Thats a heck of a chimney,



A turn damper or a barometric or both will allow you complete control over the effective height of the chimney.


----------



## Shane (Aug 8, 2006)

Isn't there language in NFPA211 that will allow you to decrease the flue size to help correct over drafting situations?  I remember reading about it in AlternativeEnergyRetailer they were quoting the changes made for the new edition. If I remember correctly for the flue size to be reduced it had to have manufacturer approval.  I will need to read through my 2003 edition tomorrow and see if I can find it, so please don't take the preceding statement as sound advice until I can confirm.  Or maybe Elk could look through his handy dandy cd version for us. I remember a couple of Appalachians with 8" flue collars that you could reduce to 6".  I would look into a barometric damper that will definately help your situation.  You could pretest your draft before actually purchasing.  You could even install a liner system and test the draft just to see what your getting into.


----------



## Shane (Aug 8, 2006)

Heck just throw a couple 90 degree elbows in there.  That'll reduce the effective height of the chimney ;-)


----------



## jschardine (Aug 8, 2006)

I believe I see how a barametric damper would help my situation, but it still sounds like there is some doubt as to whether it will actually be a 100% workaround.

If the non-cats are going to be a risky proposition (I would still like to know more about the maximum height of the PE 3100 and the Regency I3100 non-cat stoves), would I be better off going with a catalytic model that is tested by the manufacturer to work at 40'?  This brings me back to the question about the only catalytic that this dealer offers that will fit my chimney requirements (a Buck 80 or 91).  If I go with this stove, is this a good stove?  This dealer says it is, but two chimney sweeps I've asked said that they aren't up to par with other stove manufactures.  Should I look for other catalytic stoves other than Buck?  Suggestions?

John S.


----------



## elkimmeg (Aug 8, 2006)

One of this sites long time members, Victoria Fireplace  also an advertiser is a buck's dealer, with live chat  abilities Karen Duke,
 she can answer your Buck questions. Buck stoves have been in business for over 30 years. Long enough  and staying power, not to be a fly by night company.  I do not recall one buck stove complain in the 4/5 years of participation on the Hearth site. Have you checked the consumer rating part of the Hearth?



> but two chimney sweeps I’ve asked said that they aren’t up to par with other stove manufactures



 Why not compare the epa ratings  haw many grams per hour emmission and effeciency. to other possible stoves you are considering purchasing. Isn't the Epa  independent testing facility? I would put that be over a couple chimney sweeps oppinions.


----------



## BrotherBart (Aug 8, 2006)

Yep. I failed physics but majored in hydraulics in aviation. What Elk is talking about is the drop in effective pressure that occurs going from a small pipe to a large one. It doesn't work that way when you are pulling, just when you are pushing.

Chimneys are the opposite of plumbing and hydraulics. Lower the pull, smaller diameter chimney, and you lower the draft. The way a damper does it.

The reason a monster oversized chimney does not draft is that ya can't heat it enough for it to pull.


----------



## jschardine (Aug 8, 2006)

Thanks for the replies, everyone.  This information is very helpful.  I'll talk to the stove dealerto see about installing a barometric damper.  It sounds like this may be an option if I decide to take a risk with a non-cat stove.  If I install a non-cat stove and damper, I'll let you know how it works.

John S.


----------



## jschardine (Aug 9, 2006)

I'm about to make a decision on whether to go with the non-cat or cat unit (the dealer will support a non-cat if I watch temps closely and don't overburn it), I have a few final questions regarding a damper.

1.  As this is an insert, if I insert a damper into the pipe during installation, is there any way to clean the damper without removing the stove?  The dealer recommends not installing a damper into the line because it will not be possible to clean the damper.

2.  A turn damper (is this simply a manually controlled damper?) and a barometric damper were both mentioned in some of the threads.  I'm assuming I'd have to remove the insert from my fireplace to adjust these dampers, especially a turn damper?

3.  If I install this unit without dampers as suggested by the dealer, and the stove continually draws too much, would adding a couple 45 degree turns later on decrease my draft?

John S.


----------



## MountainStoveGuy (Aug 9, 2006)

1) no, thats the problem with baro dampers in inserts.
2) that is correct
3) it might, but it might not decrease it enough, and that would be a problem.

It seems the only solution is to either buy a hearth mount stove, (the hearthstone homestead is designed for that purpose) or to buy a cat insert. You will not be happy with a non cat that sucks the firebox dry in a short amount of time, not to mention the risk of damaging it. My showroom stove overdrafts and it burns half as long as the identical model that i have in my home.


----------



## BrotherBart (Aug 9, 2006)

Ok I will be the sucker and stick my chin out here and take the punch.

Why can't he put the damper in the liner up top? Sure it is a pain in the butt to climb up to adjust the damper, but if he has overdraft he should be able to find the damper sweet spot pretty fast and not have to adjust often. And it would sure beat the heck out of pulling the insert.

<crawling under the desk for cover now>


----------



## MountainStoveGuy (Aug 9, 2006)

Good question BB, here is what comes to my mind.

what about cleaning the chimney? you would have to remove the damper to get the brush all the way down, if you dont, the damper could get shut accidently by the brush, it would just be a pain. You would have to pull the insert and disconnect the liner every time you want to mess with it, including cleaning it.


----------



## BrotherBart (Aug 9, 2006)

MountainStoveGuy said:
			
		

> Good question BB, here is what comes to my mind.
> 
> what about cleaning the chimney? you would have to remove the damper to get the brush all the way down, if you dont, the damper could get shut accidently by the brush, it would just be a pain. You would have to pull the insert and disconnect the liner every time you want to mess with it, including cleaning it.



Top or bottom they have to be removed for brushing the chimney. At least if it was mounted up top in the liner at the flashing it would be a no brainer to take it out for cleaning the chimney. Easier than getting a lot of chimney caps off. If would be more prone to creosote buildup up top but then the chimney cap is a creosote factory too and I doubt that a chimney fire has ever originated thirty or forty feet from the fire box.

Also, if one has to be installed I would darn sure rather it be supported by holes through the flashing than the walls of a .005 liner.


----------



## MountainStoveGuy (Aug 9, 2006)

Thats exactly where chimney fires originate, Most creosote formation is in the last third of the chimney pipe. 
Your sugestion on having the damper up top is a good one, if i were to put one in thats where i would put it. I still wouldnt recomend it, based on the manufacture says its a no no, even though the dealer says its ok, in the case that there is a problem it will be up to the dealerto fix it with no manufacture support. That usually doesnt go over very well.


----------



## BrotherBart (Aug 9, 2006)

OK. I'm checking out of this one. I was just curious.


----------



## Eric Johnson (Aug 9, 2006)

BrotherBart said:
			
		

> MountainStoveGuy said:
> 
> 
> 
> ...




They usually don't originate there, BB, but the ones I've seen start at the firebox and work their way up the stack until they eventually hit the creosote motherlode. Then you see some sparks fly.

BTW, just as a point of information, I have an 8" damper on my boiler which I use all the time, but it's located before the cleanout tee so that it's not in the way when the time comes to run a brush up the stack.


----------



## MountainStoveGuy (Aug 9, 2006)

Thanks for clarifying that Eric, i knew that the top third had something to do with it!


----------



## elkimmeg (Aug 10, 2006)

What about a motorized damper top or bottom  controledby motor opening x amount many oil burners have them ina 6"  connector pipe


----------



## Todd (Aug 10, 2006)

JohnS said:
			
		

> I'm about to make a decision on whether to go with the non-cat or cat unit (the dealer will support a non-cat if I watch temps closely and don't overburn it), I have a few final questions regarding a damper.
> 
> 1.  As this is an insert, if I insert a damper into the pipe during installation, is there any way to clean the damper without removing the stove?  The dealer recommends not installing a damper into the line because it will not be possible to clean the damper.
> 
> ...



What is the inside diameter of your chimney? Does it have a clay liner already inside in good shape? What about a direct connect?  Since you have such a tall chimney any stove may draft good even if the chimney diameter is larger than the stoves flue collar?


----------



## jschardine (Aug 10, 2006)

I have a clay flue liner that has a 9 1/4" x 12 1/2" inside diameter.  It's a newer house, and the flue is in perfect shape.


----------



## Todd (Aug 11, 2006)

JohnS said:
			
		

> I have a clay flue liner that has a 9 1/4" x 12 1/2" inside diameter.  It's a newer house, and the flue is in perfect shape.



Ask your dealer if that size flue meets the maximum diameter flue size for the stove you are looking at. A direct connect to the flue may work, since the chimney is so tall. And It would save alot of money.


----------



## elkimmeg (Aug 11, 2006)

Code wise the only direct connect to that size chimney that has a chance of working is  from an 8" flue collar
 if an outside exposed chimney evenit is too large for even *" inter chimney code wise it would be ok
 You must have a rather large fire place opening, for the mason to have used a modular clay liner, instead of the conventional 12 /12

 The croos-sectionar area of that flue is  more than 200% larger than code  will allow for a 6" flue collar

 There is another way to look at it besides stove specs look at the liner manufacture's specs  What if you used 6.5" diameter liner would that add to the supported height? The stove manufacture claim a height according to using 6" but what if 6.5 is used and the height is supported by the liner manufacturer. Check out liner manufacture's specs . Is there any way you can place an in line damper  in the connector pipe if needed?


----------

