2 story house. Water heater in the garage and is vented into the garage ceiling. Problem is when I go into the attic I don't see a vent pipe anywhere in the vicinity above where the water heater should be that's leading to the roof. Am I missing something? Surely this doesn't just vent in between 1st and 2nd story or into the attic right?

Plumbers just replaced the water heater and when he went up into the attic he was surprised he couldn't find the vent either. He said he felt a cool breeze of air through the vent pipe as he was connecting the water heater so he was confident it was venting to the outside. How concerned should I be? House built in '04 and we've lived here since '12. I have c02 detectors on all floors and they've never gone off.

Also, this may be unrelated because the plumber mentioned it appeared to be from a previous water leak from the upstairs bathroom that is basically directly above this, but this area has always bothered me. I'm hoping it's not from improper venting from the WH. This has been like this for 10 years plus, without change in shape or size.

Does it turn and go horizontal in between the first and second floor?

Probably easiest to start outside and find your vents on the roof. Depending on how many gas appliances you have and where they are, that could be an easy way to figure out where it discharges by process of elimination.

For a lot of reasons, very unlikely to just vent into an attic - though we've seen strange things on this board before.

I guess it could turn and go horizontal between the floor but this isn't a power vent water heater so I figured it has to vent out the top of the roof through the attic?

And in my attic above the 2nd floor I don't see any other pipe venting to the roof other than the one connected to my gas furnace up there. There are standard roof vents for ventilation but they obviously aren't exhaust vents.

Can you see your entire roofline in your attic? How many gas appliances do you have, including the water heater? Also, to be clear you have no vent pipes at all going out your roof?

I definitely have some roof vent pipes that I can see when I'm looking at my roof from a distance. Tomorrow in the daylight I can try to count them. I have 3 gas appliances.... Water heater, furnace and stove. I guess that means I should see 3 pipes? Just seems weird I didn't see anything other than the one from inside the attic but maybe I can't see the entire roofline from there..... And I'm also clueless at what I'm looking at haha

if i were you, i'd cut a small hole in the ceiling there and look. i'm not so sure that story of the bathroom leak is the reason for that staining. it's worth it to find out. you can do a simple patch to repair that hole you cut (unless of course you find worse problems)

Is there a way to tell of it is venting properly from the flue? Could I put a c02 detector on top of the water heater and see if it goes off?? Should I be feeling any hot air escaping out from under the flue where there is that gap between it and the WH?

I did have a thought. That corner is on an exterior wall. When I go outside there are 3 vents on side of the house between the 1st and 2nd floor that have the cover with the flaps. I know one is for the dryer that is in that same area and I think another is for one of the bathroom exhaust vents, but could the 3rd be for the gas water heater? Could it run horizontally between the floors and exit side of house? If that is the case, should I be able to feel hot air coming out of one of those when the water heater is actively on?

Yes, they can vent from the wall or roof.

When I get home today I'll try to take more pictures of some things. Would relieve my mind that it was venting out between the first and second floor from one of those "flap" vents on side of my house, but since those style vents have the flaps closed when no air is passing through, I wouldn't think that would be a viable vent for the WH because there wouldn't be able to be a draft through that pipe constantly.

Those 3 vents on side of the house look like this:

A vent from a furnace or water heater should not have a plastic cover. I wouldn't think that it would have a louvered cover like that, but I was on the HVAC side, not plumbing. There is enough heat that any cover should be metal.

The brown vents are exhaust fans (possibly a dryer.)

That water heater vent will go through the roof and be the size of the pipe you see in the garage with a rain cap on it.

I have seen them go up through the attic near the edge of the roof so that you really cannot see much from the attic because they are down in the area without much space that is hard to get to and see.

Yes you are right. Those can't be for a WH vent. Plus, the water heater is an atmospheric vent type so I'm reading those have to be vented vertically through the roof. But I'll see if I can count the vent pipes on my roof and look at their location closer. Maybe I just visually can't see the pipe or vent cap when I'm inside the attic because they are close to the edge of the roof on that side of the house.

This isn't my house but it's a similar one in my neighborhood. So just so I'm clear, I'll be looking for something on my house like what I circled? One of those pipes coming up from the roof that is on the edge basically directly above where my water heater would be?

No. Those that just come up like open pipes are plumbing vents. No issue if rainwater gets in.

Water heater vent should have a rain cap on it like the one further to the top right in your pic.

No, that is a plumbing vent pipe.

It will be more like the one at the top of your picture (though that one is a furnace vent.

Typically it will be directly above the water heater. They are allowed to go at angles, but rarely do.

Well crap, I'm 99% sure I don't have one of those bigger ones with the cap on the far edge of my house in area above water heater but I'll check location and count this afternoon.

Probably like #4 maybe?

Again, not my exact house, but this is what I should see? This looks like it is probably placed directly above the water heater in the garage. My water heater would be in a similar spot on the wall at the back of the garage.

Should also be at least as big around as the vent leaving the water heater.

FDXAg said:

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Again, not my exact house, but this is what I should see? This looks like it is probably placed directly above the water heater in the garage. My water heater would be in a similar spot on the wall at the back of the garage.

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Probably. The other one to the top of the house is probably a gas furnace.

There is usually a code requirement to vent a minimum distance horizontally from the roof (i.e. 10' horizontal ). Consequently, steep pitched roofs have longer vent stacks than shallow sloped roofs. Also, they are all usually longer than the short plumbing vents.

It is also possible that the stack came off in a storm or something, which would explain the water leaks.

Top view of my actual house. Don't see anything on roof that is in the circled area where my water heater placement would roughly be in the garage

Yes to the one on the last picture. As stated, the cap can blow off sometimes.

In your picture. What is the silver blob to the left of the circle? That seems likely to be it. Too blurry in the picture to tell.

Probably out the side wall or it may be one of the other ones just outside the circle.

need a clearer picture.

Maybe that thing just to the left is the vent. The silver larger circle just to the north of the circle is a roof vent I believe. I'm having a hard time judging roughly where my WH is located in the garage. I will check when I get home and report back. Thanks for help so far everyone. Don't want to assume all is well when possible carbon monoxide issues could be present

Based on the shadow being similar to the furnace vent on the top of the house in the middle, I am pretty sure that is it. Can see how it would be hard to see with the house next door. If you stand way back front or back you should be able to see it from the ground. BTW, it doesn't have to be as tall as the one in your example picture of another house, but should look like that one with a cap and a rain collar.

Upon inspection when I got home, that is the vent for the water heater. It was hard to see from the street with the neighbors house and tree like you said, but it appears to be in the exact spot over the water heater area. And it's the same looking vent and cap as the one for the furnace that's in the middle of my roof.

I appreciate the help everyone! Definitely relieved my mind to know what to look for.

Glad it got figured out. Sorry I missed the replies. I was prepared to pull hi res say and get it figured out. Lol.

Good to hear. Never fun to wonder about a potential issue.