Mystery gas leak- what/where could it be?

[dbates]

Our new furnace has a small gas leak that you can smell coming out of the intake opening (or any other opening air can go through including those in the box holding the AC coil). You only smell gas after the unit has been idle for awhile and it stays around until the heat comes on. The gas appeared to be leaking out of the metal tube coming out of the gas valve that supplies gas to the burners.

Original installer detected the leak but Rheem phone tech said "some gas smell was normal" so contractor didn't fix it right away. I paid for another Rheem contractor to do an inspection, he detected the leak, said it was definitely not normal and that the honeywell gas valve needed to be replaced. So the original contractor replaced the valve and I still have the gas smell. Oh boy.

Everyone thought replacing the valve would fix the problem so I am at a loss. I can't find any posts with similar issues either. Anyone have an idea what could be causing this?

[Tech23]

Not sure what they are using to detect the leak, we use an electronic explosive gas leak detector. There are many places it could be coming from, including the water heater, or somewhere else on the gas line prior to the furnace or in the furnace.

Around here people can call their gas company and they will come out for no charge and find the leak, red tag it and then you can call a plumber or hvac company to replair the leak.

Not everyone is on the same experience level at finding leaks, or anything else for that matter.

Good luck,

[tipsrfine]

It is simply insane to imagine any competent hvac person not to be able to pin-point a natural gas leak originating from a known location.

[dbates]

Not sure what they are using to detect the leak, we use an electronic explosive gas leak detector. There are many places it could be coming from, including the water heater, or somewhere else on the gas line prior to the furnace or in the furnace.

Around here people can call their gas company and they will come out for no charge and find the leak, red tag it and then you can call a plumber or hvac company to replair the leak.

Not everyone is on the same experience level at finding leaks, or anything else for that matter.

Good luck,

Both contractors used electronic gas detectors. Sorry if I was unclear but the leak is inside the furnace. Since the gas seems to be seeping out into the tube that feeds the burners they thought replacing the gas valve would solve the problem. But no dice. I can't tell you how many times folks have been out here working on this furnace so I am hoping a guru has an answer that they haven't thought of.

[Tech23]

Do you smell the gas all the time...24/7 or just sometimes?

[dbates]

It is simply insane to imagine any competent hvac person not to be able to pin-point a natural gas leak originating from a known location.

Is there any other reason you can think of that would cause a leak such as this in a Rheem furnace? For instance, could we have too much gas pressure coming into the house and it is somehow forcing its way through the gas valve resulting in a slow and steady leak? Could the board be malfunctioning and the valve is not being closed all the way? They already checked all the pipes and connections and since the valve replacement did not fix it I am merely looking for other possibilities.

I don't know much about furnaces (I'm sure you can tell) and I cannot find anyone posting with a similar issue. I'm waiting to get the furnace swapped but this is really gnawing at me.

[tipsrfine]

Both contractors used electronic gas detectors. Sorry if I was unclear but the leak is inside the furnace. Since the gas seems to be seeping out into the tube that feeds the burners they thought replacing the gas valve would solve the problem. But no dice. I can't tell you how many times folks have been out here working on this furnace so I am hoping a guru has an answer that they haven't thought of.

There should be a gas shut-off very near the furnace. Shut it off and see if the smell goes away. If it does, you know the leak is on the outlet side of the shut off. At that point, there is a very limited amount of pipe that the leak could be comming from-what maybe 2 or 3 feet?-COME ON! This is ridiculous! A simple gas sniffer and some bubble solution solves this problem in minutes! I could find this problem with my nose.
Have they confirmed the inlet gas pressure to the gas valve is at the right pressure?

[Tech23]

You said new furnace has gas smell...
You said gas valve was replaced and smell is still there...
The likelyhood of two new gas valves leaking gas is extremely small.

Too much gas pressure coming in will not let the valve open and light the burners, so if the burners light, you probably do not have enough pressure to be pushing its way through the closed valve.

There may be a leak at the pipe that goes into the valve or somewhere near the valve, like at a union or other fitting.

[dbates]

Do you smell the gas all the time...24/7 or just sometimes?

You start to smell the gas maybe 5-10 minutes after the furnace shuts off? I will have to time it to be sure. The gas hangs around until the furnace goes into heat mode and then it gets exhausted out or burned up and you don't smell it anymore. Wait a few minutes after the furnace shuts off and then the smell comes back. It eventually fills up the front of the furnace, then seeps out of the intake and the holes in the metal box that sits on top of the furnace that holds the AC coil. The gas smell continues to come out of the furnace until it heats up again. Its not a powerful gas smell, it just keeps going and going like its a small and steady leak. I'm pretty sure it would stay there 24/7 if the furnace didn't heat up.

They tried shutting off the gas, purged the unit and the smell went away. Turned the gas back on, let it heat for a bit and shut off. Tested it right after and no reading. Waited a few minutes and tested it again and set off their tester. I'm assuming this is why they thought it was a bad valve.

[Tech23]

I agree with Tipsrfine...it is ridiculous that they cannot find the leak.

[dbates]

There should be a gas shut-off very near the furnace. Shut it off and see if the smell goes away. If it does, you know the leak is on the outlet side of the shut off. At that point, there is a very limited amount of pipe that the leak could be comming from-what maybe 2 or 3 feet?-COME ON! This is ridiculous! A simple gas sniffer and some bubble solution solves this problem in minutes! I could find this problem with my nose.
Have they confirmed the inlet gas pressure to the gas valve is at the right pressure?

I do not know if they confirmed the inlet gas pressure. But I shall write that down.

[dbates]

Ok I dont know if this helps, but I finally found someone else who appears to have a problem similar to mine that was posted on another hvac site. But they dont say their make/model of furnace nor how long the gas smell stays around for.

Like us, the gas readings and smell appears to originate from the manifold where the burners are attached. They were also told it was a bad gas valve and replacing it did not fix the issue for them either. Admin for that site said you should not continue to smell gas in that area because after the unit shuts off the ventor motor should stay on and should exhaust any remaining products of combustion.

I have noticed that the little see through window on the front of the furnace gets fogged up if the heat hasn't kicked on for awhile and the gassy air that comes out of the intake hole is 85% humidity (I measured it with my reptile hygrometer). We are in arid Colorado and our indoor humidity is about 20%. Outside tonight with snow on the ground its about 40% humidity so where is the super humid gas stuff coming from? So is it possible that our furnace is not venting out the leftover gas and products of combustion? Could all of this be an exhaust issue and not just a gas leak? How the heck would we check that?

[SwanyJ]

I just was wondering if you have had any determination as to the cause of this problem and what the resolution was. I am having the same issue with a new furnace and it is very frustrating as I am sure you can attest to.

Thanks.

[tipsrfine]

Ok I dont know if this helps, but I finally found someone else who appears to have a problem similar to mine that was posted on another hvac site. But they dont say their make/model of furnace nor how long the gas smell stays around for.

Like us, the gas readings and smell appears to originate from the manifold where the burners are attached. They were also told it was a bad gas valve and replacing it did not fix the issue for them either. Admin for that site said you should not continue to smell gas in that area because after the unit shuts off the ventor motor should stay on and should exhaust any remaining products of combustion.

I have noticed that the little see through window on the front of the furnace gets fogged up if the heat hasn't kicked on for awhile and the gassy air that comes out of the intake hole is 85% humidity (I measured it with my reptile hygrometer). We are in arid Colorado and our indoor humidity is about 20%. Outside tonight with snow on the ground its about 40% humidity so where is the super humid gas stuff coming from? So is it possible that our furnace is not venting out the leftover gas and products of combustion? Could all of this be an exhaust issue and not just a gas leak? How the heck would we check that?

You are just going to have to shop around for an experienced hvac pro and have them come out. This is something that can be quickly diagnosed by a pro using the proper testing instruments. Period.

[dbates]

I'm curious, do you have a Rheem?

The contractor pulled the old Rheem unit (because it was incredibly noisy and oversized etc.) We never did fix the problem on the old unit. I had a new model installed and it has the same gas smell (even worse)! This time they ran the intake to the outside of the house so its not as noticible but it is still there. I am beginning to think it is an issue with either the Honeywell valves or the Rheem furnaces. I am told that the new HE furnaces dont purge out the gas in the same way as the older furnaces but I am really unsatisfied with the situation.

There was also something from Honeywell that said their valves have a "trace leakage phenomenon" and that customers are supposed to be educated. DOH. They seem to place the blame on the furnace manufacturers. But I think they are having a problem with their valves and might switch to another brand if I can. I'm told Rheem does not allow you to lengthen the purge to help get rid of the gas and its a factory setting. This is not a little whiff of gas that dissapates, but quite a bit that hangs around all day.

"Gas appliance manufacturers are aware of the problem of residual gas venting into the area surrounding the furnace and are working to reduce it. There are tradeoffs, however, in allowing more venting. With current test procedures, more venting after shutoff tends to reduce the efficiency of an appliance. Honeywell encourages manufacturers to select newer designs to reduce the presence of unburnedgas around the appliance and thereby reduce the number of leakage complaints." I linked to their PDF below.

http://hphaa.com/knowledge/FAQs/gas-valve-leakage.pdf

In my case, the furnace is in the basement where I work. So everytime I walk into the storage area, I can smell the gas (even with the intake vent routed outside). It makes me crazy since my ancient furnace never smelled at all! I'm getting the new furnace inspected today and I am going to ask the inspector about it. They should give me an unbiased answer. Like you, I would like some piece of mind.

I have another problem with the new furnace but that is another post.

[tipsrfine]

Nice link. I learned something new.

[Roddy73]

Me too, but I wonder how much effeciency they'd lose by running the inducer fan a few more seconds.

[dbates]

Nice link. I learned something new.

Well it would be nice if that info was readily available. I had to search to find anything and my contractor thinks I'm crazy. So Honeywell knows their valves have leakage, the furnace manufacturers should know they aren't venting out the gas well enough, but the consumer just has to live with it. Why not give us the option to decide for ourself if we are willing to lose a bit of efficiency and lengthen the purging? I know I would definitely do it since my setup is apparently condusive to the gas just piling up in my basement!

Yeah, so frustrating!

[Roddy73]

Well it would be nice if that info was readily available. I had to search to find anything and my contractor thinks I'm crazy. So Honeywell knows their valves have leakage, the furnace manufacturers should know they aren't venting out the gas well enough, but the consumer just has to live with it. Why not give us the option to decide for ourself if we are willing to lose a bit of efficiency and lengthen the purging? I know I would definitely do it since my setup is apparently condusive to the gas just piling up in my basement!

Yeah, so frustrating!

It's just as frustrating for the contractor who has to make free service calls because the appliance he supplied is stinking.

[SwanyJ]

Thanks for the thorough communication. No I do not have a Rheem but I appear to be having the same issue and I do not know what to do.

I spent all this money on a new furnace and now I am feeling I just should have had the old one repaired since I never experience any issue like this with that one.

Please let me know if you get any insight from the inspector or anyone else. I am desperate.

Thank you!

[dbates]

Thanks for the thorough communication. No I do not have a Rheem but I appear to be having the same issue and I do not know what to do.

I spent all this money on a new furnace and now I am feeling I just should have had the old one repaired since I never experience any issue like this with that one.

Please let me know if you get any insight from the inspector or anyone else. I am desperate.

Thank you!

Definitely! The only thing I have done that makes me feel a little better is I purchased a combustible gas detector from Home Depot (they might still be on sale and I think mine was about 30 bucks). Its a pen model and detects leaks that are 20LEL and above. I tested it when they did the new install to make sure it worked. Its not fancy but its a little piece of mind.

So when I smell gas I check it to make sure its not going over 20LEL and I feel a little better. Otherwise how would we know if the "normal" gas leak/smell gets to be abnormal? At this point I'm not calling the contractor unless it goes off since the gas smell is there all the time anyway. Plus its a good instrument to have around the house since we have other gas appliances.

[small change]

Are there any freshly painted rooms in the home or any paint cans or other solvents near the furnace?

Trying a shot in the dark

[dbates]

Are there any freshly painted rooms in the home or any paint cans or other solvents near the furnace?

Trying a shot in the dark

For my situation nope. The get a gas reading from inside the furnace with their sniffer and 3 contractors said there is gas leaking in there (which is why the gas valve was replaced with another honeywell valve on the first furnace which didnt help). The same thing is happening with the second furnace and the last thing my contractor told me is that I might have "Dirty gas" or "heavy gas". Just not enough gas is leaking out that its causing any flames to erupt and they say we won't go boom. I wish it was just paint or that my dog had gas LOL. I'd feel much more secure. =)

Not sure about Swanyj's situation.

[Methanemann]

After the burners shut off, there is still unburned gas sitting in the manifold, which can cause a very minor odor for short time. Is the area where the furnace is very air tight or in a drafty basement? I find many gas valves have very minor seepage through them.. usually not enough to smell a few inches away but my CGI will almost always pick up something from it. I guess it is possible that the replacement valve is defective. See if you can sense any smell from the burners after the furnace has been off for an hour or so.
Another thing you can do is turn off all the pilot lights off in the house, water heater, fireplace, whatever. Go out to your gas meter and find the test dial. The test dial will have a marking on it that says 1/2 cu ft, or something similar. Try to get the dial on the upswing by running the stove burner or something, then take a pen and mark the exact spot the dial hand is at. Wait 10 minutes or so. See any movement? if so, turn off the line valve to the furnace. Did it stop? If there is movement and it stops when the line valve is closed, the leak is in your furnace. If it continues to move, the leak is in the houseline or at a connection some where else.

Good luck.

[Roddy73]

Just another shot in the dark here, but if you live in an area with an older natural gas system and just experienced any heavy fluctuation in outside temps the odorant levels could be a little high and that little amount of gas that's hanging around can stink really bad.

The gas utility I worked for had an old odorant system that didn't react fast enough to quick changes in weather, if we had a big swing we'd be getting gas odor calls like crazy at our meter sets.:callpro:

Hopefully Rheem comes up with a solution if it's their problem.

[ZeroTolerance]

All these people and their unreliable POS electronic detectors that cost them a pretty penny. Dose the line with some Big Blue or soapy water. Geez, I dont own any electronic sniffers or detectors and probably never will. My nose leads me to gas leaks and then I spray the general area with big blue and WAHLA there it is.

Only time I will have to buy a leak detector is if I am working on a multiple evap system just to get the general location of the leak.

[SwanyJ]

Are there any freshly painted rooms in the home or any paint cans or other solvents near the furnace?

Trying a shot in the dark

No I do not have this situation either but thanks for trying!