One of my neihbors asked me to check a roof leak for them.
Looked in the attic to see where it was coming in.
Moisture isn’t coming in , it isn’t getting out. Condensation is running down the inside of the B-Vent to a forty five degree elbow and running out . I watched it happen.
So how should it be fixed?
Thanks
Replies
How high is the B-vent above the roof?
Might not be high enough, and acctualy back drafting some. Bad news there. CO, and CO2 not getting out.
Bob Walker will be along shortly with more knoweldge to share on this.
Dave
good point- didn't think of it.
bump
Hey hubcap...........would you please answer Dave's questions!?
And while you are at it check out the rain cap to see if it is there.
Is the pipe installed with the correct end up?
The answers will help in generating a solution to the problem....hopefully.
................Iron Helix
rain cap is there.
pipe is installed right side up (water would stay inside the pipe if it was backwards i am thinking.)
so i'll check the stack heigth
Bob's in the Tavern, busy saving the world.
Joe H
maybe an anti bob has an idea?
bump
>>Bob's in the Tavern, busy saving the world.And if you ever need saving,Joe, try someone else. Most people save the little personal swipes for the tavern. Tnis is the real world, with real lives and health and expensive appliances at stake, and no one needs that kind of petty bs here.
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Sojourners: Christians for Justice and Peace
Edited 3/9/2005 8:03 am ET by Bob Walker
Just wanna make sure I under stand -
By saying "B-Vent", you mean bathroom vent?
Are you talking the plumbing vent pipe, or a pipe from a bath fan?
B-vent is the double wall vent used for venting gas appliances.
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Sojourners: Christians for Justice and Peace
Thanks.With us rednecks, you have to "B-specific"(-:
It is when we forget ourselves that we do things that are most likely to be remembered.
yep.
what bob said.
Yeah, I klnow, I inspect some of your homes sometimes {G,D&R!}
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Sojourners: Christians for Justice and Peace
Simple (at least for stage 1:) The furnace (and water heater) are not venting properly.
There are several things that can cause that condensation in the B-vent, almost all bad.
First, how big is the problem:
Start with looking at more stuff.
How old is the house? How close are mature trees to the house? What kind of terrain?
How does the outside of the b-vent look above the roof - probably has a lot of rust. If it is a "recent " development, check out the surrounding houses - they will often have similar problems (but not always, depending on many of these factors listed)
How high above the roof is the b-vent and what is the pitch of the roof? Height depends on pitch AND whether there are any vertical surfaces within 10'
In most cases (in my area), the vent is too low or too close to the ridge; in some cases the b-vent extends too high above the roof. (See attached pics, 0697, 0706, and 0704)
0706 is a two-fer - the B-vent is too long/exposed but not high enogh above the adjacent roof. I was amazed there wasn't any rust on the outside, but check out the condensation leak pics.)
Assuming the furnace (boiler?) and water heater share that flue, look closely at the top of the water heater under the bonnet to see if there is any rust.
How are the two flues joined together? "Y" or "T"?
Look closely at the underside and behind and below the draft inducer to see if there are any leak marks, rust or powder. (See attached pics. The draft inducer picts, 3603 big and small- indicating file size, are from a 90+, but the issues are the same.)
Look at the heat exchanger for rust in or below the openings to the heat exchanger.
What kind of space are the furnace and water heater in? Is there 50 cubic feet of open space for every 1,000 btu? If not, how many btu do they have, is there a dryer in the space, and what kind of air supply is there between that space and the rest of the house and outdoors.
Now, you'll have some idea of the magnitude of the problem.
To diagnose it properly, you'll need to use at least a draft gauge and ideally a CO meter or combustion analyzer.
The solutions could be: redesigning the venting. (The vent design tables do not claim to work in all situations, and ultimately leave it to the person designing the system to make sure it works. Many (most-in my area) heating contractors never test their installations for proper venting.
The draft inducer might not be operating properly. The flues might not be properly joined. The air supply might be limited.
Backdrafting might only occur in certain situations: wind from a certain direction; vent fans being operated, certain doors being left open (e.g., the garage door.
MOST IMPORTANTLY (in my opinion) is how much condensate has gotten into the heat exchanger and what kind of damage has it done to it?
(In my area) many HVAC contractors are behind the times and aren't really equipped to do this sort of analysis.
Try to find a contractor who has trained in the National Comfort Institute's (or the Building Performance Institute's) Carbon Monoxide Analysis protocol.
You can the names of the former in your area by calling the NCI at the 800 number on their web page.
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Sojourners: Christians for Justice and Peace
Edited 3/9/2005 8:43 am ET by Bob Walker
thanks for the info Bob. I will pass it along to the homeowner with a recommendation to get in touch with someone from the list.
If you can, keep us posted as to what the problem finally was and how it was solved.This is an area of knowledge that is still being developed and the more experience reported the better
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Sojourners: Christians for Justice and Peace
Is there a bird nest or other blockage up top?
no.
i looked- fergot my camera.
there is a fair amount of rust stain on the outside
the furnace and water heater share the vent via a y
lotta rust and mineral on top of the water heater
house is eleven years old, no trees to speak of
no make up air
top of the b is below the adjacent peak
i'll get pics and post
meanwhile( back at the oasis) the homeowner can follow up with one of bob's
recommended sites
thanks again bw
no make up air
I think you're on to something here...