Wood Stove Chimney close to Furnace Flue, yes or no?

[Hoopdancer]

I couldn't find anything anywhere about how close a wood stove chimney can be placed to a furnace flue at roof level. I'm in the planing stages and trying to figure what the best location is for the stove pipe to my new Hearthstone Heritage (in my imagination I have one already) within a few inches. I want the stove pipe to go straight up from the stove with no bends for the best draw but it will come within a foot or less of the furnace flue. I don't know code issues on this one but it seems wrong to do this. I imagine that building codes differ from place to place but is there a general rule of thumb that any of you pyro's have come across that might cover this one? I'm pretty sure that the stove pipe will be the priority and if I have to I will move the furnace flue.

 

[BurningIsLove]

I dont think there is a clearance issue. Many chimneys today have double flues which have the stack top exits about 12" apart. In mine for example, the furnace and wood stove flues appear to be a common chimney, even though they have separate flue liners & masonry bricks. Below are some pics of my chimney setup during construction

https://www.hearth.com/econtent/index.php/forums/viewthread/4222/P15/#44850

In my setup, the running of the stove & furnace are mutually exclusive though. My hot water is electric, so my furnace isnt used for that.

 

[elmoleaf]

I'm not sure about Canada, but in the U.S. the horizontal separation between lined flues in a masonry chimney is usually one wythe of masonry 4" wide. Not positive on the vertical separation between flue terminations, but may be 6". Factory built chimneys probably have different requirements.
Check with your local building inspector or fire department.

 

[gyrfalcon]

I couldn't find anything anywhere about how close a wood stove chimney can be placed to a furnace flue at roof level. I'm in the planing stages and trying to figure what the best location is for the stove pipe to my new Hearthstone Heritage (in my imagination I have one already) within a few inches. I want the stove pipe to go straight up from the stove with no bends for the best draw but it will come within a foot or less of the furnace flue. I don't know code issues on this one but it seems wrong to do this. I imagine that building codes differ from place to place but is there a general rule of thumb that any of you pyro's have come across that might cover this one? I'm pretty sure that the stove pipe will be the priority and if I have to I will move the furnace flue.

This question struck me because I just had a SS chimney put in for my woodstove last year which goes right up next to my existing masonry chimney the boiler in the basement is connected to. Mine was installed by a very cautious and careful chimney guy certified and trained up the yin-yang, so presumably knows what he's doing. The SS chimney is maybe 4 inches from the existing chimney, and in fact is bracketed to it in three or four places for stability. (The masonry chimney is itself already stabilized by guy wires to the roof.)

Since I had the woodstove installed, I've decided to try for 100 percent wood heat, so I'm hoping not to use the boiler at all, but at the time the 2nd chimney was put in, I was expecting to continue to use the boiler for back-up in cold weather.

It never occurred to me to question having the two chimneys so close together. What have I missed? What are you concerned about? What is it that seems wrong to you about it?

 

[Hoopdancer]

Thanks for your input. I didn't know about double flues. I just thought that with the way smoke goes when a huge low pressure system comes in that there might be a small chance of some misfortune if one flue is not warmed up or exhausting at that moment. Sometimes a back draft happens down a chimney not in use and I thought that maybe there could be a code issue but from your responses all should be good. I've seen smoke from my tepee chimney hug the ground not very far away during a high to low pressure change and thought that gasses from the furnace or wood stove could migrate down the adjacent flue. That's what made me a little leery. I guess I'm reading way too much into it (and no I don't have a furnace in my tepee ;-)).

 

[gyrfalcon]

Thanks for your input. I didn't know about double flues. I just thought that with the way smoke goes when a huge low pressure system comes in that there might be a small chance of some misfortune if one flue is not warmed up or exhausting at that moment. Sometimes a back draft happens down a chimney not in use and I thought that maybe there could be a code issue but from your responses all should be good. I've seen smoke from my tepee chimney hug the ground not very far away during a high to low pressure change and thought that gasses from the furnace or wood stove could migrate down the adjacent flue. That's what made me a little leery. I guess I'm reading way too much into it (and no I don't have a furnace in my tepee ;-)).

Oh, I see! Well, you're right, the existence of double-flued chimneys should put that worry to rest. In any case, I hope you've got a CO detector. I think actual smoke is a little different because the particles are heavy enough to sink.