buderus vent pipe

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  #1  
Old 03-25-09, 11:43 PM
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buderus vent pipe

hard to get a good answer on this. brand new buderus G124X/25. couldn't get 5" solid pipe through the masonry flue for venting.

one stack, three flues, but when the previous owner installed gas inserts in the 2 fireplaces, he destroyed the throat and removed the dampers. so venting the boiler directly through the masonry flue is not an option (it has to be lined.) if i did, the boiler exhaust would circumvent the gas fireplace inserts in the other 2 flues and fill the living rooms.

plan 'b' was implemented: b-vent from the boiler room, which is in a daylight basement. however, i'm evidently not getting enough draw from the boiler flue with this setup. the house has a slightly gassy/humid odor. not raw natural gas, but it's as if the boiler isn't burning all of the fuel.

so my big, fat, burning question is if this boiler can be vented with flex piping.

i destroyed multiple solid 90 bends trying to get solid-pipe venting through the masonry.

now i will attempt to get clearance through that flue with a 12' piece of rebar and a 5-pound hammer. the option of using aluminum flex will make my life easier, but i'll do what i have to in order to get draw from that boiler flue.

the local buderus dealer says, "no," to aluminum flex, but buderus themselves are mum on the subject. understandable, since they don't necessarily manufacture their products to american states' building codes.

if the b-vent flue can be removed and i can vent through the masonry flue, i can convert the b-vent hole to a fresh air vent, which is, of course, win/win.

any advice/experience in this matter?

and, yes, the CO detectors are mounted and working.

thanks.
 
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Old 03-26-09, 02:53 PM
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Can oval shape work?

Not clear on your particular difficulty.
On a G124X-32 needing 6" flue, where masonry was tight due to mortar lumps, I made the rigid aluminum into oval shapes, by placing a 3' board on a section and kneeling on it. Just have to do each the same. Then screwed three sections together, and lowered down the now 9' sections, fastening each to the next as we went. Temporarily strapped it so as not to lose it at each juncture. If the el at bottom is the problem, no clue here.
I don't think B-vent is required inside a masonry chimney.
 
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Old 03-26-09, 02:59 PM
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oops

Oops. Reread it. Your troublesome B vent is out its own port in the house. Never mind my last.
We sometimes only see the patterns we know.
 
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Old 03-26-09, 07:58 PM
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What is the "B" vent doing when it exits the structure?
 
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Old 03-27-09, 08:26 PM
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rbeck:

the b-vent currently has a "hood" fashioned from a corrugated steel chimney topper.

which worked great at first when the wind was blowing. however, the wind died yesterday and the boiler puked up a blocked vent fault and shut down. and it looks like kaka.

update: i have pulled some of the broken 90's all the way through to the bottom of the masonry flue, so it can be done. it's just going to take a careful balance of finesse and force.

joewalbran: i like the idea of deforming the pipe enough to clear the masonry. the area that's giving me trouble, though, is an old smoke shelf. it creates a jog that just happens to be about 5 inches wide. once the liner clears that obstacle, it has to bend about 35 degrees from vertical, then take a 90 out of the bottom of the chimney and into the boiler room.

so my dilemma is that the bottom 5 or 6 feet of the liner has to be a bunch of 90's screwed together to make those two turns. 90's can pull apart with about 40 pounds of force. and if i deform them, they won't rotate to make angles.



i'm working on chipping out enough of that smoke shelf to allow the pipe to pass with less muscle.

i don't think anyone makes a 12 foot long rotohammer bit... so pounding at it with rebar is all i have at this point.

and i'm going to attach rope to the liner going both ways out of the masonry next time, so that if pieces get stuck, i can assist it from either end of the flue. or easily remove broken pipe.

i'll let y'all know what transpires.

thanks for the replies.
 
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Old 03-29-09, 09:23 PM
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done and done!

i got the solid pipe through the flue with one mishap: the uppermost 90 on a big chain of 90's broke when i was about 4 inches from being completely through the stack. fortunately, it broke so that i was looking straight down into it. so i scabbed a male flange onto the end of the straight run and eased it down into the end of the broken 90. no screws in that junction, of course, but gravity and heat sealant should seal it nicely.

as soon as the liner was connected, i could feel draw from the boiler room. the house is cooking once again. and now i have a fresh air vent, to boot.

i gotta tell ya', though, this was two weeks of my life i wish i had back.

then again, i'm thankful i'm not in kansas right now.
 
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Old 03-30-09, 12:01 AM
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Congratulations

You earned that one!
I have a misshapen 90* and hope the high temp silicon continues to seal a 1/8th inch gap.
 
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