water vapor in natural gas


Just wondering if anyone knew what effect a larger than normal water content in natural gas would have on energy output of a furnace? I have a gas pipe that goes through an unheated area, and I'm having condensation plugging the pipe on the coldest mornings. This line has been in place for 20 years and I've never seen the problem until the last two weeks. The local gas company doesn't have any answers on why so much water vapor of late.
Could it be they are stretching the cubic feet with water vapor?
Thanks, Bill
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bill allemann wrote:

Pretty much reduce it in direct proportion to the molecular concentration.

I'd venture that over the twenty years condensation and what entrained moisture there is has built up in a low point and is now of sufficient volume to have become a problem. I would expect if you shut the gas off and either drained the line or blew it out w/ compressed air your problem will go away for at least another twenty years. (Assuming, of course, the gas company has been out and checked for and didn't find any leaks...)

HIGHLY unlikely -- to the point of a blanket "no". There's an outside chance there could have been some moisture introduced during some maintenance activity, I suppose, but injecting water, no. Oh, one other pretty remote possibility could be a water trap somewhere has failed in the distribution system, but in general those are at collection points and compressor stations, etc., not even close to residential customers (unless, of course, you just happen to be near such a facility).

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My gas lines in my house had a "T" with a leg about 8" long, capped off. The leg was vertical and was designed to serve as a moisture trap Do you have these? If so, shut off your system and see if the gas company will drain them for you??
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Drained it three times in the last 2 weeks. I have a tee fitting there now, as described in one of the other posts.
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dpb wrote:

...
...
Actually, I realize I didn't put down the most likely culprit being a water trap in your line that has filled up...look for a stub w/ a shutoff valve and cap or a lower loop plumbed into the supply line also w/ cutoff valve(s) and unions or other removable connections to drain it...
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If the gas piping happened to be hung such that the water drained back to the meter, wouldn't the meter fail? The inlet and outlet are both at the top of the meter housing. In the last two weeks about a quart of water that I've drained would have ended up in the meter.
At a low point, I have a tee and a downward pointing stub that catches water, but the problem is that it's filling up in maybe 5 days during cold weather.
Bill

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bill allemann wrote:

It it is filling up in five days not five years, you have a problem with the supply. It is possible there is a leak underground. Contact your supplier.

--
Joseph Meehan

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Very interesting. Last Winter I call the gas company because my burners were giving a very orange flame. They sent a guy out within a half hour and said that's a CO problem! When the guy arrived, the flame had gone back to normal blue.
But they were talking of gas shortages back then and I wondered what do they add to the natural gas supply to "thin it out". Propane was the answer and that is more expensive and burns hotter than natural gas, so it didn't make sense. Water vapor makes more sense.
Joseph Meehan wrote:

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Stubby wrote:

Water vapor would make no sense. Condensed it takes up very little space and it would likely condense along the way and air mixed with natural gas would only cause problems. On the other hand air could be used (cheap and it would not likely condense, but it would cause a hazard if the ratio got too high. There is nothing I can think of that would work and would not cost more than natural gas. Also the regulators would take a very dim view of any such stuff.
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Joseph Meehan wrote:

...
Correct deduction on water vapor. But, depending on the service area, it is possible the utilities are making up supplies from imported LNG by "re-liquifying" it. In order to do that an meet Btu requirements, etc., it is sometimes desirable to use some inerts. There are three basic possibilities used--nitrogen, air, or flue gas. Of these, air and to a certain extent, flue gas do have entrained moisture to greater or lesser degrees. Also, particularly in western areas, the newer gas fields making up for the depleting earlier fields are high in methane and inerts/contaminants as compared to historical supplies since, say, the 30s & 40s when the shift from "manufactured gas" to natural gas became prevalent until quite recently.
So, there is a possibility of OPs supplies having some mixing issues, but the supposition that there is water vapor induced on purpose is a fallacy. It certainly does seem as though recently there must be a difference in his supply if it is requiring draining a trap so frequently is required regularly. If his supply is so high in moisture, however, it would seem that all homes in his area would be suffering as well, so unless he's "just lucky" in having a location that collects the moisture in an unheated area that freezes, there should be enough complaints to cause some action by the utility. If that isn't occurring, makes it seem as though there still might be some localized problem but I can't come up w/ a really plausible scenario for it.
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I've been wondering that myself ... there seems to be a lot more water in the gas these days ... like maybe more water than gas :-) I've got those pumps on my furnaces ... the water condenses out into a reservoir and gets pumped (condensate pump) form there into the abs drain. On the old furnace, which was also high efficiencey, it was sufficient to just drain the water off under the basement slab.
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Where are you, in relationship to the age of the gas main system. If you are in an old city still using cast iron pipes sealed with oakum and lead, the same way that cast iron sewer and drain pipes are sealed, you probably are on wet gas. New systems use dry gas because they do not need to keep the seals moistened. The old systems were built for manufactured gas which had a lot of moisture in it. The new dry gas has to have steam injected to prevent the oakum seals from drying out and leaking. Sometimes they will use oil vapour. In old cities you will find iron fittings in the sidewalks and/or roads with the word "drip" cast in the small lid. These are not a comment on peoples attitudes but a place where excess moisture or oil will drip down to, allowing it to be pumped out.

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In an older neighborhood.

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My best friend runs his vehicles on compressed natural gas, his compressor is in his basement, he pumps to 1500 pounds.
He had to add a heater to prevent condensation freezing and complains the company equitable has become sloppy about water getting in gas.
his cars have been on natural gas since the mid 70s but his troubles only began a few years ago.
have you called the gas company and complained?
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They sent a tech out. He made sure the meter wasn't damaged, and pretty much just told me all I can do is redo the piping to allow insulation, etc to lessen the condensation. When I said that he forgot to ask how old this installation was (20 years), he started getting more and more vague. I started to get the feeling that he had heard all this many times recently. Several more attempts at asking about why this happens after 20 years got nowhere.
On the way out, I mentioned that this was good info for me on deciding what kind of heat to use in some other properties I'm developing. The guy just smiled.
Bill

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not that this will eliminate the problem, but let's spotlight it. ask the gas company replace the gas meter and look inside the pipes with the meter removed, with a licensed experienced hvac man or plumber. and check with your neighbors for similar problems. they may be very happy to hear from you if they have heating problems.
bill allemann wrote:

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