New Gas Water Heater combustion odor

[fordman84]

Hey guys, I sure hope someone can help me with this. Two days ago I installed a new GE 30 gal natural gas water heater. I hooked everything up and it all seems to work well, except there is a STRONG combustion odor. It doesn't smell like straight natural gas (not "garlicy" enough) so I think it is the exhaust gasses. It started immediately, so I thought maybe it was the "newness" burning off. We left windows and the back door open and went to bed. The next morning it was still making a stink so I shut it all down. Last night I replaced all of the venting...again. It is double walled vent that runs straight up and through the roof, and I replaced it all the way up and out with a new cap. No fix, it still starts kicking out a stink as soon as I start her up. I did a smoke test and air is being drawn up through the draft hood. I can't figure why it would still be leaking. There are no leaks at the inlet line. I have triple checked all connections with the bubble stuff I use for checking HVAC lines. If it was leaking I would see the bubbles for sure. I also checked the pipe from the little thermostat to the burner and no leaks. It has to be the exhaust side. Anyone else know anything else I can try. The only thing I haven't done but could think of are as follows:
The hole where the vent pipe goes through the ceiling isn't sealed up yet, so there is about 2 inches on either side of the pipe that I need to put cover. Could that be doing something? ( highly doubtful but want you to have all the info).
Also, the vent cap up top is new, so I wonder if it could not be allowing enough fumes out, creating a logjam. It is the cap sold with the vent pipe I bought from home Depot, so it isn't a mismatched item I just threw together.
Or, does the pipe have to stick a certain amount out of the roof? Right now the pipe sticks about 3-4 inches out of the roof collar, then has the cap on it that sticks up about 3 more inches. Could this be too high or too low? I can see the cap from the front of my house, and it is on the back slope near the top ridge. Could it be allowing a draft to blow over the ridge and back down into the vent pipe? IF so is there anything I can do to lower it since that double wall stuff can't really be cut.

What a pain. HOpe you guys can help out though.

[SSN596]

As you know, carbon monoxide is odorless, but other combustion products do have an odor. It is a good sign that you see draw into the draft hood. But since your new water heater is an FVIR type, combustion air supply is more important than ever. Is there and adequate supply of fresh air ? Is the WH located in and enclose area, or an open area like a garage? Are there other gas burning appliances nearby?

I think this needs to be investigated, and in most areas the gas utility will send out a technician who can measure for CO, and test for gas leaks with a more sophisticated tester. I would not rule out a gas leak until this is done.

Have you looked inside the viewing window to see if you have a nice blue flame? Is it possible that you have the wrong gas ( i.e. a propane model running on natural, or vice versa)?

[fordman84]

Thanks for the response. What you posted are a few things I am going to check when I get home (the unit was shutoff before I left of course). I know it is a natural gas water heater, that was the first thing I thought of when I smelled the odor...and that is a bad gut feeling when you think of all the work you just did.

The color of the flame I need to check. The heater is not aroundany other gas appliances, but it is in my laundry room. I am thinking there may not be enough air flow, I am hoping at least. The heater is in a corner, and our electric dryer is next to it. So basically it has 3 walls close to it. I have been looking around this morning and that seems to be my best hope so far. I am going to move the dryer away and see if that helps. If it does, easy fix. one of the walls leads out to the garage, so I could cut a hole and install an intake vent there. I read one place saying I would need one 6" hole. At least we live in Texas so we it doesn't get REALLY cold here. Or are there any other ideas to fix the incoming air problem?

[fordman84]

Hey guys, I figured I would give everyone a headsup as to what was wrong. Yes, I fixed it. Yes, I feel stupid now because it should never have gotten this far. I went home and double checked EVERYTHING, because I knew there had to be a problem somewhere. I set up a fan to force more air into the area of the water heater and that didn't fix anything. So I shut it all down and let the room clear out and started from scratch. I was able to narrow exactly where the odor was coming from, and it was the little thermostat box on the front. I got out my leak check goo AGAIN and tested everything, no leak. Then I decided to check the little pilot light tube even though I never touched it. Guess where the leak was? I pulled that fitting out, put some thread tape on it (yes, the yellow kind for gas) and tightened it back up. Viola! No more leak, no more smell. At least I know the chimney vent is bullet proof now and completely replaced/safe.

Thanks for all the ideas here. At least I learned a valuable lesson. Just because it came from the factory, doesn't mean it is correct!

[LazyPup]

Glad to see you were able to locate the problem.

FYI- if your roof is a 6/12 pitch or less the vent opening in required to be 12" above the roof surface when measured on the lower side of pipe. If you live in a region that gets snow your local code will probably require 12" + the average snow load for your locality.

The minimum vertical length from the water heater to the roof vent opening is 5'.

[fordman84]

Thanks lazypup, I'll check the code standards here. I don't know what our roof pitch is, I know it is VERY low though (to the point where I am 6'1" and I can't stand up in the attic at the highest point. As for snow, I live in DFW, TX...so what is this "snow" stuff you talk of

Anyhow, it does stick out quite a ways from the roof. I had to put in another adjustable elbow to make sure everything was straight and in line, and that added about 6" to the part sticking out of the roof and it was already at least 6" out.

I really do appreciate the help and heads up to make sure I don't kill myself or burn down the house. You do everyone on this board a great service!