Can you connect two stove pipe elbows directly to each other?

[NorEaster603]

Is it "legal" to connect two 45 degree elbows (single wall stove pipe) directly to each other to make a 90 degree? Or do you need a section of pipe between them? If so, what is the minimum length of pipe required between elbows?

This article states you cannot link elbows directly together, but since it also states 45 degree elbows are not allowed, I'm thinking this is for class A chimney pipe not single wall stove pipe:

Frequently Asked Questions for Fireplace and Stove Venting

Lots of threads on here talk about using two 45's instead of a 90, but nothing I have seen has mentioned the details about how to actually do this. For background, in order to center my stove on the hearth, the pipe will have to shift sideways a bit before entering the masonry chimney. I am trying to plan out how to do this, which involves calculating offsets. For aesthetics I would prefer to minimize the diagonal travel, making it as close to the thimble as possible.

The simplest way I can imagine accomplishing this is with a 45 degree left, then a 90 degree into the wall (clocked 45 degrees to meet the diagonal of the first 45). However, I'm thinking it might also be possible to use two 45's instead with better draft. The first 45 would be rotated 45 degrees toward the wall as well, and the second clocked 45 degrees to join it. The minimum offsets in each case would involve directly connecting the elbows to each other, which got me wondering if this is even allowed. I want to make sure my plan is reasonable before getting too deep into building the hearth.

I'm dreaming of a simple CAD program for sketching these things out. Imaging being able to load components from the major suppliers and tinker with them before buying. But I digress...anyway, thanks in advance!

 

[gthomas785]

Sure you can connect two elbows together. Just like connecting any other pieces of stove pipe.

However, I'm pretty sure that what you are trying to do with the 45s is impossible. Try it for yourself but as soon as you rotate one of the elbows off the vertical plane the other one will need to be more than 45 degrees.

I have the same situation in my house, and my pipe goes up off the stove to a 45 then a 90 into the wall.

 

[GrumpyDad]

Is it "legal" to connect two 45 degree elbows (single wall stove pipe) directly to each other to make a 90 degree? Or do you need a section of pipe between them? If so, what is the minimum length of pipe required between elbows?

This article states you cannot link elbows directly together, but since it also states 45 degree elbows are not allowed, I'm thinking this is for class A chimney pipe not single wall stove pipe:

Frequently Asked Questions for Fireplace and Stove Venting

Lots of threads on here talk about using two 45's instead of a 90, but nothing I have seen has mentioned the details about how to actually do this. For background, in order to center my stove on the hearth, the pipe will have to shift sideways a bit before entering the masonry chimney. I am trying to plan out how to do this, which involves calculating offsets. For aesthetics I would prefer to minimize the diagonal travel, making it as close to the thimble as possible.

The simplest way I can imagine accomplishing this is with a 45 degree left, then a 90 degree into the wall (clocked 45 degrees to meet the diagonal of the first 45). However, I'm thinking it might also be possible to use two 45's instead with better draft. The first 45 would be rotated 45 degrees toward the wall as well, and the second clocked 45 degrees to join it. The minimum offsets in each case would involve directly connecting the elbows to each other, which got me wondering if this is even allowed. I want to make sure my plan is reasonable before getting too deep into building the hearth.

I'm dreaming of a simple CAD program for sketching these things out. Imaging being able to load components from the major suppliers and tinker with them before buying. But I digress...anyway, thanks in advance!

Those are referring to chimney pipe, you cant have 45's apparently. Nothing to do with your stove pipe. I believe 2 45's are preferable to a 90 actually because there is less restriction. The experts in here can chime in on that one.
As far as how it looks, I honestly was pretty disappointed when I couldnt go straight up but after said and done I kinda like the offset look.

 

[stoveliker]

Correct.
Two 45's are better than one 90. No need to have pipe in between, although it might help with the draft a bit.

Also note that double wall chimney pipe is better than single wall.

What stove is this for?

How tall is the chimney from stove top to chimney cap?

 

[NorEaster603]

Correct.
Two 45's are better than one 90. No need to have pipe in between, although it might help with the draft a bit.

Also note that double wall chimney pipe is better than single wall.

What stove is this for?

How tall is the chimney from stove top to chimney cap?

Nectre N550, roughly 4ft up to the thimble then another 16 ish feet to the cap (6” in insulated SS liner in masonry flue). It’s a single story house if that helps.

 

[NorEaster603]

Sure you can connect two elbows together. Just like connecting any other pieces of stove pipe.

However, I'm pretty sure that what you are trying to do with the 45s is impossible. Try it for yourself but as soon as you rotate one of the elbows off the vertical plane the other one will need to be more than 45 degrees.

I have the same situation in my house, and my pipe goes up off the stove to a 45 then a 90 into the wall.
View attachment 311280

Definitely appreciate the inspiration pic. You’re probably right about the two 45s not working but i haven’t tried anything IRL yet

 

[NickW]

I did what you are doing with 2 90's directly to each other. Don't have a pic on my phone and I'm not at home. If I remember I'll post one tomorrow or Friday...

 

[NickW]

 

[stoveliker]

That's not two 90s?

 

[NickW]

That is 2 90's

 

[gthomas785]

That is 2 90's

No

 

[NorEaster603]

That is 2 90's

Idk it looks an awful lot like two 45s…thanks for posting the picture either way

 

[NickW]

No

Yes, mine is 2 90's. The lower one is twisted so the bottom 2 sections are twisted to be straight and the third section is at about 45. The upper one is twisted to less than 90 to line up with the lower and horizontal pipe, but is close. I might have gotten a 90 & 45 to work? I am agreeing with you that 2 45's probably won't work. My setup is effectively similar to @stoveliker.

 

[NorEaster603]

Yes, mine is 2 90's. The lower one is twisted so the bottom 2 sections are twisted to be straight and the third section is at about 45. The upper one is twisted to less than 90 to line up with the lower and horizontal pipe, but is close. I might have gotten a 90 & 45 to work? I am agreeing with you that 2 45's probably won't work. My setup is effectively similar to @stoveliker.

Oh i see they are adjustable sections. That makes more sense

 

[gthomas785]

Yes, mine is 2 90's. The lower one is twisted so the bottom 2 sections are twisted to be straight and the third section is at about 45. The upper one is twisted to less than 90 to line up with the lower and horizontal pipe, but is close. I might have gotten a 90 & 45 to work? I am agreeing with you that 2 45's probably won't work. My setup is effectively similar to @stoveliker.

Lol, an adjustable elbow isn't a 90 unless you set it to 90 degrees!

 

[begreen]

That is 2 90's

Yes, they are adjustable elbows that have been set to different angles. Two 45's can work for some situations. It depends on the flue outlet location relative to the wall thimble.

 

[Wildflush]

All depends on your setup (stove) and chimney height. I have a 90 going into my wall thimble and a class A tee on the outside side of the wall. Also 2 offset 30’s to clear my gutters. Top of stove to cap about 23’. Even with these restrictions my stove drafts extremely well.

 

[Wood Rat]

What's the shortest piece of double wall vent pipe you can buy...uh...asking for a friend.

 

[stoveliker]

6" I think.

But why not take out another section and add a telescoping piece that you can make "standard+ short"-length?

 

[Wildflush]

6" I think.

But why not take out another section and add a telescoping piece that you can make "standard+ short"-length?

Yup my installer used a telescoping piece of Excel double wall. Makes it easy to disconnect from stove collar to clean my chimney.

 

[Wood Rat]

I like that idea of using a telescoping piece to make up the difference in lost length and for ease of cleaning. *Note to self, research Excel double wall telescoping pipe.

 

[Grinnell]

i have 2 45s but with 5 feet of straight pipe in between

up 3 feet from the stove then the 5 str feet of pipe and then a 45 into the T which is connected to the liner