Draft and cleaning question: straight or horizontal venting

[dave360up]

My mother is having a PE Spectrum installed in an enclosed porch that is open to the rest of the downstairs. The dealer was going to vent it straight up through the roof of the enclosed porch. There would be no way to lean a ladder against the pipe on the outside so it would have to be cleaned from inside using a telescoping section above the stove. A person who is doing some work for her on the house said he could do the intall for much less than the dealer and would put in a horizontal run and go out the side of the porch and put in a cleaning T outside. This would also keep the top of the stack further from the peak of the main roof. so he feels it would draft better.

My question is how much of an effect the horizontal run would have on the draft, and if the angles involved make cleaning more often necessary. Would the chimney have to be taller anyway because of the horizontal run and have to be cleaned more, thus negating the supposed advantages of it? I'm guessing the horizontal run would be 4-5 feet.

 

[Battenkiller]

My mother is having a PE Spectrum installed in an enclosed porch that is open to the rest of the downstairs. The dealer was going to vent it straight up through the roof of the enclosed porch. There would be no way to lean a ladder against the pipe on the outside so it would have to be cleaned from inside using a telescoping section above the stove. A person who is doing some work for her on the house said he could do the intall for much less than the dealer and would put in a horizontal run and go out the side of the porch and put in a cleaning T outside. This would also keep the top of the stack further from the peak of the main roof. so he feels it would draft better.

My question is how much of an effect the horizontal run would have on the draft, and if the angles involved make cleaning more often necessary. Would the chimney have to be taller anyway because of the horizontal run and have to be cleaned more, thus negating the supposed advantages of it? I'm guessing the horizontal run would be 4-5 feet.

Without seeing pics of the intended install, there is no way to determine which way might be best for your needs.

A horizontal run is best avoided. You shouldn't go beyond 4' if you do, with a minimum of 1/4"/ft rise in the run. This will also introduce two 90º elbows into the system. All of these things will lower the available draft. If you go with 45º elbows, you will need an even longer angled run - 5.6' to shift the vertical section over 4' (7' if you need to shift it 5'). You can eliminate the influence of the roof peak by going taller. Rule is the top should be a minimum of 2' above a horizontal line that extends 10' from the chimney to the nearest point on the roof.

 

[dave360up]

Thanks for the input so far and the rule of thumb for clearance to the roof. I will try to get some pictures.

 

[DAKSY]

Rule is the top should be a minimum of 2' above a horizontal line that extends 10' from the chimney to the nearest point on the roof.

Not quite. To meet code, the chimney must extend thru the roof for three feet, on the high side, THEN it has to be 2 feet higher than anything within 10 feet horizontally.
The BEST way to determine this height is to take the rise of the roof (top number of the pitch i.e. "7" for a 7/12) & multiply it times 10, then take that number & add 24" to it.
So, for a 7/12 pitch, the top number, 7, x 10 = 70". Add 24" = 94" out of the roof.

 

[Backwoods Savage]

Yes, it depends upon the horizontal run amongst other things. We had a horizontal run of about 2' before going vertical up the side of the house. We installed with 1/2" rise per foot of horizontal and in addition, our chimney is theoretically too short. We get along just fine.

 

[Battenkiller]

Not quite. To meet code, the chimney must extend thru the roof for three feet, on the high side, THEN it has to be 2 feet higher than anything within 10 feet horizontally.

The BEST way to determine this height is to take the rise of the roof (top number of the pitch i.e. "7" for a 7/12) & multiply it times 10, then take that number & add 24" to it.
So, for a 7/12 pitch, the top number, 7, x 10 = 70". Add 24" = 94" out of the roof.

Thanks, Daksy, I'll save that info in my "Wood Burning" folder. It's gotten fatter since joining this site last year. ;-)

 

[Battenkiller]

So, for a 7/12 pitch, the top number, 7, x 10 = 70”. Add 24” = 94” out of the roof.

Wait, that doesn't make sense. A chimney almost 8' out of the roof no matter where it's placed? Mine's near the peak of the roof. It's not within 10' of anything.

 

[dave360up]

Here are some pictures of the house and inside where the stove will go. It is to replace a cracked el crappo fireplace that was in the house that was vented vertically. The inside pics kind of show where it was. The PE stove would be centered on the area where the old fireplace was. That makes the floor-to-ceiling height a little over 7 feet at that point, just matching the minimum requirement in the PE manual. The dealer wanted to go straight up with the venting and was hoping to go up just 9' above the roof, but was going to add another 3' section if necessary. The other guy was going to go out to the right (as facing the stove) just below the ceiling. It would emerge from the eave in between the window and the end of the enclosed porch. There is some room to have some rise in the "horizontal" section, but not a lot. It is 4' from the center of where the stove will go to the wall where the proposed thimble will go. 45 degrees is too much rise to fit, but maybe something like 30 degrees or less will fit, though that increases the length of the run beyond 4 '.

So, is straight up better or over and out?

 

[begreen]

First thought. I don't like this location for the stove. Move some furniture into this area or make it the media room and liberate some space to place the stove in the heart of the house. It will do a better job there. That shiny pipe, going up many feet is going to look out of place on the old house and the stove will do a lot better job heating if it is located in the main part of the house.

 

[dave360up]

The last suggestion on this thread was to move the stove to a new location in the house. That is actually what we decided to do. Here is the new location as seen from inside and from the front of the house.
The stove is actually the Super 27, not the Summit as I earlier wrote.

So, now I have a new question. My mother does not want the chimney to go up through the floor into the second floor, so it has to go through the wall to the outside. To minimize jogs in the vent pipe and to avoid cutting into the eave, is it possible to run the vent pipe at an angle through the wall to the outside, or do the through-the-wall kits only go straight through? There is a hole drilled through from the outside to the inside of the house that can just be seen in the photos. (You will have to click to see them full size to see the hole). It marks the edge of the eave and thus the outer edge of a class A chimney on the outside of the house (the gutter is easy to cut away there).

If the vent came up from the stovetop then angled toward the wall and through at a compound angle (angling up and toward the corner, away from the little porch eave), the only bends would be the bend toward the wall and the connection to the exterior chimney. If it has to first angle toward the wall, then jog toward the corner and level out to go through horizontally, then go vertically on the outside, it will be adding turns.

The clearances from the stove are fine as long as double wall pipe is used.