ice in gas line


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Old 03-05-09, 10:45 AM
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ice in gas line

location: Northeast Ohio

This is really more of a commercial heating question but since I have had similar issues at home, I am hoping you same experts might be able to help.

My wife runs the office at our temple and is therefore responsible for the building. Over each of the last two winters, there were occasions where the gas meter stopped delivering gas. Both events had overnight temps in the single digits (F). Knowing that it happened last year, my wife called in the fall and had the gas company install heating tape and insulation before things got cold. When it stopped delivering gas recently, the gas company came out again and said the meter was frozen. They installed more heating tape and insulation. It is a large commercial meter with a 4" or 6" supply line (?).

There was some discussion about replacing the meter but the gas company tech said it would make no difference as these commercial meters are all the same and very sensistive. He did suggest building an insulated shelter around the meter. We are not so pleased with this as it would require not only a building permit but a city architectural review board since it is visible from the street. Also, an insulated structure is going to be fairly costly.

In addition to the gas meter issue, the roof mounted heating unit for my wife's office stopped working today. The heating tech came out and determined that there was ice in the gas line on the roof leading to that heater. He said this was the last heater at the end of the gas line and the most used unit so it was most suceptible to the blockage. He disconnected the line and allowed it to blow itself clear. He said that some crud did come out.

All this tells me that there is still water in the gas lines and ice related blockage in the line is likely to happen again.

Should the gas company be doing something about moisture in the line? How do we get their attention?

Can the rooftop gas line be insulated?

Should we really consider building an insulated shelter for the meter? Similar sized buildings on either side of this one have not had a problem.

Is there anything that can be done?
 
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Old 03-05-09, 11:54 AM
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There are a couple of basic types of natural gas utility services to homes.

One is an intermediate pressure system, with gas pressures of from 10-50 PSI up to the pressure regulator, where the pressure is most often cut down to 1/4 PSI for the gas piping in the house.

Here's a picture of that kind of meter set assembly:

Gas meter - Wikipedia, the free encyclopedia

The pressure regulator is the sorta circular attachment in the gas line above and to the left of the gas meter.

I'm guessing that you do not have a regulator like that as part of the meter set.

With a 4-6" gas supply line, you almost certainly have a low pressure system at your temple. Replacing those meter when they get water logged is a fairly big job, which is probably why they didn't want to do it. They should though ---- the meter bellows can get full of water causing you to get billed for more gas than you are using.

I'd call the utility and ask them to change out and test the gas meter for accuracy because of the water contamination. I'd also talk to the gas distribution supervisor in your area about getting a tank or other kind of protection for the gas meter to prevent this kind of intrusion in the future. It would probably need to have accumulated water pumped out from time to time.

The state utilities commission in my state required gas utilities to change out and test gas meters once per year at no cost if customer requested that service. --- you might ask about what your utilities commission requires


That low pressure system tends to be vulnerable to water getting in and accumulating in the mains, services to houses and gas meters, and when they freeze up they stop, just as you describe.

The gas utility where I used to work used to have a fair amount of low pressure systems, and when they froze up we went out and fixed them. That often involved changing out the gas meter, pumping out water tanks installed to collect water and pumping out "drips" which were pipes down to low spots in the service where water accumulated and from which it could be pumped.

If you have been having repeated problems with water disrupting service, you might want to nag your utility to improve your service by installing a drip line or tank which will drain off an accumulate water rather than getting into the meter or your home appliances.

If the utility isn't supportive, a complaint to your utility regulators might get them motivated. The Washington State Utility Commission required my old utility to replace ALL of it's low pressure gas mains, which probably eliminated pretty much all of that kind of problem.

You could also install "drip legs" where your gas piping comes into the house and at each appliance. These are nothing more than a tee pipe fitting with a piece of vertical pipe going down which will accumulate water rather than passing it along the piping system.

Your utility should figure out how to protect you from this kind of service interruption. Filing complaints with regulatory agencies when that happens may get that process started. The real solution is to replace the mains with a modern, higher pressure system.
 
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Old 03-05-09, 06:28 PM
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great feedback

Thank you SeatlePioneer for the info.

You have some great suggestion about drip lines and tanks. I am concerned about being able to get the gas company to pay for the drip lines since it sounds like they would need to be inside the facility and most of the time their service stops at the meter.

The replacement of the meter is probably prudent but at this point it is actually running low - showing less than the actual usage. The gas company tech was aware of this and chose not to do anything. With a gas bill of $6000 for January before it froze and about $3000+ for February after it froze I kind of like it this way.

I will take your info back to my wife and let them decide how to proceed.

Thanks again.
 
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Old 03-05-09, 09:36 PM
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Yes, drip legs on your side of the meter would be your nickel, I would suppose. If you wanted to be fancy you could put a bypass around the main drip leg with valves on it so gas could be diverted around the drip leg without shutting off the gas, allowing the drip leg to be removed, inspected and emptied periodically.
 
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Old 03-06-09, 05:14 PM
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S/p

Wouldn't the drip leg be best on the upstream side of the meter? I might be mistaken but I think around here they install a drip leg either upstream of the regulator or between the regulator & meter, not sure which.
 
 

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