B vent leaking from seam in pipe?

ChrisJ

While doing some work in the attic I noticed my B vent had some white stains running down the side. Saturday during a storm I was up there and noticed an occasional drip run down from the bottom of the seam in the pipe that passes through the storm collar.

Best I can tell, the drip is coming from the inside of the seam rather than the outside of the pipe. The outside of the pipe looked, and felt dry.

What gives ?

Zman

It sounds like the flue gas is condensing before it has left the flue. This can cause premature flue failure.
Is the boiler short cycling? What are the return water temps?
How much of the flue in run in unconditioned spaces?

JUGHNE

I was going to suggest that also but ChrisJ's steam boiler probably wouldn't think of short cycling.

But it is down fired, could the flue be too large now?

ChrisJ

Zman said:

It sounds like the flue gas is condensing before it has left the flue. This can cause premature flue failure.
Is the boiler short cycling? What are the return water temps?
How much of the flue in run in unconditioned spaces?

JUGHNE said:

I was going to suggest that also but ChrisJ's steam boiler probably wouldn't think of short cycling.

But it is down fired, could the flue be too large now?

I originally thought this as well, until I watched it dripping during a storm and the boiler was off. The boiler also ran a few times when it was dry outside and no signs of moisture or a leak.

Perhaps it's only rain that gets blown into the rain cap? It was very windy out during the storm.

The water drips on a piece of wood in the attic which apparently has always dried before causing an issue. There's a chance this has been going on since 2011 and it's caused no actual damage. Yet.

I just can't see it being normal or expected of the product. The system is a Simpson Duravent B vent.

It's approx 30' tall 6" connected to a 125,000 btu/h input boiler.
The only sections in unconditioned space are in the attic and above and it's about 8 foot total including 2.5 above the roof. Personally, I feel it drafts a whole lot better and faster than any masonry chimney.

JUGHNE

Don't have any Simpson here to look at. But Hart & Cooley ends have a small opening on the crimped inside seam that could let water in if the wind was just right working on the cap. The inside aluminum seam is almost lined up with the outside galv seam. About an 1" or so offset.

ratio

I typically see tiny leaks along the seam where the b vent goes through the flashing. It takes a sealant of some kind to make a water tight penetration. I've had to run a bead of silicone all the way up the seam to keep the water out before.

Zman

The white streaks sure say condensate to me. How is the integrity of the cap and B vent above the roof?

kcopp

I am willing to bet that's its rain following that seam down.
If you dare hit the seam outside w some silicone.
B-vent is a great way in my opinion to naturally vent an appliance. Heats up quick and you get a very good draft.

ChrisJ

Zman said:

The white streaks sure say condensate to me. How is the integrity of the cap and B vent above the roof?

I understand where you're coming from, but the white stains are just oxidation from the rain water IMO.

Here's an outside shot I took today. I can't stand the storm collar as it was kind of "made on the spot" right before a bad thunderstorm in a panic. I mean, the guy made it work so kudos for that but it's kind of ugly.

kcopp said:

I am willing to bet that's its rain following that seam down.
If you dare hit the seam outside w some silicone.
B-vent is a great way in my opinion to naturally vent an appliance. Heats up quick and you get a very good draft.

I'm trying to set up an appointment with a guy as we speak.
I can do a lot, but I'm not going up on that roof. 30 feet up and it's a 9/12 pitch. I know my limitations, and that's one of them.

The fact I didn't see any signs of leaking while the boiler was running on a dry day and I saw it leaking during a bad storm and the boiler was off has me pretty confident it's not condensation. I'm not saying it doesn't get some when it's -8F outside and cold in the attic, I have no idea, but I don't think it's the main concern.

Jack

Once it dries up and warms up I'd take a finger full of silicone and run it up the exterior seam on the pipe. Also, raise and re-goop the storm collar. Dura vent makes a cap called the Brider Cap that works very well and is not as open as your current cap. Every system will have certain "wet time" when the flue is cold(er) and will produce condensate until the flue warms up. B-vent is a good low mass system, when properly laid out and installed. There are many masonry systems that never warm up and condense continuously.

ChrisJ

Sigh.

Ok so I just watched the B vent leak and it's not raining out.
It drips quite a bit when the boiler first fires up, and then slows up if not stops.

I just covered my barometric up with aluminum foil as I'm concerned that's cooling the draft off too much. It's a drafthood appliance so the barometric isn't required. We left the barometric in place because it didn't seem like it could hurt.


Are B vents allowed to be run diagonally? Mine has an offset in the attic where the original chimney used to go on an angle. Because I guess the guy wanted to show off his skills in the 1860s, I have no idea.


However, my concern is no matter what I do, there's times that pipe is going to be very cold on startup and I can't see eliminating the barometric solving this.

I also swear the day I watched it leaking it was raining out and the boiler was off. So maybe, it's a bit of both?

I just watched it again with the barometric covered and there was a cold drip hanging there by the time I got up there, but nothing more came.




Here's the 7" barometric on a 6" pipe. It's currently wrapped in aluminum foil with the spill switch outside of the foil.

JUGHNE

Shows the advantage of the old standing pilot or sharing the flue with standard water heater. This may be happening in a lot of installs but few people huddle in their attic as you do .

Old masonry chimneys were often offset so it would pop thru the roof at the center of the house requiring the least height but also providing the best draft. Often hallways were in the center of the house so the offset put it out of the hall.

ChrisJ

@JUGHNE do you think the barometric has anything to do with it?

JUGHNE

I don't know.
Is your motorized damper in that horizontal section between the 90's? If you could manually lock it open and allow heat from the basement to keep the vent warm and see if that is any different.
We are running out of cold weather for these experiments though.

ChrisJ

> @JUGHNE said:
> I don't know.
> Is your motorized damper in that horizontal section between the 90's? If you could manually lock it open and allow heat from the basement to keep the vent warm and see if that is any different.
> We are running out of cold weather for these experiments though.

It's above the 90s at the base of the b vent

ChrisJ

Sorry yes. You confused me as its a tee with the bottom capped at the base of the b vent

ChrisJ

Just checked again with the b vent covered it's still dripping.

Fred

@ChrisJ , is it relatively easy for you to change the CPH and see if longer cycles changes anything?

Gordy

The advantage of B vents is as @kcopp said they heat up fast, and produce a nice draft. However they also cool down fast. I see there is quite a run through an unconditioned attic, and above the ridge. In the dead of winter when cycles are long, and shorter times between heat calls probably not much condensing at the top. In more mild weather with shorter cycles, and more time between calls vent will cool off, and not get a good burn length to heat up.

Tinman

They likely used the offset to penetrate through the back side of the gable roof, aesthetics only. The offset is fine but, like you said, no need for the barometric. @Gordy probably nailed it and/or the b-vent may be oversized?

ChrisJ

6" 30' for 125k input boiler. Was 150k originally but both have 6" connector

JUGHNE

What does anyone think of a fiberglass wrap? It says 1" to combustibles.
On most B vent installs I have done I put a wrap of FG around it where it comes thru the ceiling. I believe better than the blown in cellulose which will char and smolder. B vent isn't that hot after your first 20 feet.

EBEBRATT-Ed

I agree with @JUGHNE about at least checking into the possibility of insulating the flue in the attic. What to use?? mineral wool?

What's your stack temp??

ChrisJ

I had thought about that as well, but as has already been said, with what?

Stack temp, have no idea. I just pulled the barometric out, so it must be a little higher.

Gordy

Is it worth worrying about?

ChrisJ

> @Gordy said:
> Is it worth worrying about?

Yes

Gordy

it's condensing in the upper most part of the stack. Not much you can do about it. If your chimney were even vertical I highly doubt it is condensing enough to ever make it down to the boiler.

ChrisJ

Gordy said:

it's condensing in the upper most part of the stack. Not much you can do about it. If your chimney were even vertical I highly doubt it is condensing enough to ever make it down to the boiler.

It's leaking in the attic on some wood.
Pretty soon, it'll be leaking directly on the plaster ceiling as that wood is going bye bye.

Not sure if you know, but water and plaster don't mix.

Gordy

Isn't that how you make plaster

ChrisJ

Yep. I don't want to make plaster using my ceiling

EBEBRATT-Ed

Will not taking the barometric out reduce the stack temp by not sending dilution air up the stack??

No drain fittings for B vent. Don't suppose you can convert the upper section to AL29-4c with a drain section.......just thinking.

Trying insulation wouldn't cost much. Measure stack temp.

Is the flue oversized for the input??

ChrisJ

EBEBRATT-Ed said:

Will not taking the barometric out reduce the stack temp by not sending dilution air up the stack??

No drain fittings for B vent. Don't suppose you can convert the upper section to AL29-4c with a drain section.......just thinking.

Trying insulation wouldn't cost much. Measure stack temp.

Is the flue oversized for the input??

Removing the barometric should pull more air through the drafthood, which either will pull more air through the boiler, increasing stack temp (maybe) or just pull more air through the drafthood which will result in the same temperature anyway.

I'm really wondering if it's just leaking at the same where the storm collar meets it and it was condensating and running down there yesterday, perhaps due to the high winds.

It was 12° outside last night and I went up and looked and no signs of water anywhere.

I have a chimney guy coming Tuesday to look at it, which, we're also supposed to get rain so I'm thinking that's a bad thing.

Gordy

It could even be outdoor atmospheric conditions are right to condense just normal indoor air rising up through the stack.

Gordy

The only real way to get a handle on what is going on is looking down the B-Vent. Preferably after the boiler was running. See if it's condensing on the walls, and how far down.

ChrisJ

Gordy said:

The only real way to get a handle on what is going on is looking down the B-Vent. Preferably after the boiler was running. See if it's condensing on the walls, and how far down.

Hopefully the guy i have coming Tuesday will be able to make things right.

I do most of my own work but I'm not going on that roof.
9/12 pitch + 30 feet = me dead.

ChrisJ

Today on my agenda is properly fixing the firestop in the attic.
I need a vacuum, gloves,knife, spray foam, drywall, screws and probably 5 things I'm going to forget and have to make 5 trips down to the basement.

It's not the work that kills me, it's the constant trips up and down 3 flights of stairs.

Gordy

Driver, pencil,saftey glasses, and lunch.......

Gordy

Maybe supper....

ChrisJ

I never got up there today, but I did bend up my first flexible duct connector.

Came out pretty decent too. Last night I cut out the two 14" openings in the supply plenum which royally sucked with snips. They came out good, but I'm hurting.

Gordy

Gotta put that multi tool to good use

ChrisJ

Gordy said:

Gotta put that multi tool to good use

I don't have a multitool, also not sure how it would do cutting 20 gauge sheet metal?

I do have a new Bosch jigsaw.......I may try that on the return plenum. I have an 8", 9" 10" and a 14" I have to cut in that.