Dedicated Gas Line


  #1  
Old 01-23-04, 08:59 AM
rubin_l
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Dedicated Gas Line

I need to run a separate gas line from the meter to just outside the house to a generator. As the pipe would run, it would be about 50'.

The supply line coming right off the meter is 1" OD. I want to T into this pipe. What size pipe is needed to accomodate a gas flow of 288,000 CFH?

Though this county permits copper, I would much rather use the black steel threaded pipe since this is what the fittings to and from the meter are, and it just seems like a safer material.

I am proficient at many types of repair work but I have never worked with gas before; but I do want to try this.

Any advice is appreciated. If you think I am totally insane for wanting to do this myself, feel free to say so.
 
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Old 01-23-04, 10:46 AM
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Your totally insane for wanting to do this gas pipe work, never done it before, don't do it, we plumbers went though school to learn what has to be done.

Do your self the favor, call in a pro, get it done and over with.
 
  #3  
Old 01-23-04, 01:46 PM
enigma-2
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Re: Dedicated Gas Line

Originally posted by rubin_l
I need to run a separate gas line from the meter to just outside the house to a generator. As the pipe would run, it would be about 50'.

The supply line coming right off the meter is 1" OD. I want to T into this pipe. What size pipe is needed to accomodate a gas flow of 288,000 CFH?

Though this county permits copper, I would much rather use the black steel threaded pipe since this is what the fittings to and from the meter are, and it just seems like a safer material.
RE: 2000 IRC

For natural gas (0.06 specific gravity) at a pressure of 0.5 psi, a 50 system drawing 288 kbtu will require 1-1/4 inch black iron pipe. If you do intend to use steel, make certain it's at lease schedule 40 weight.

Minimum burial depth is 8 inches for a single appliance and susceptible to physical damage. (12 inches is better.) Check with your local inspector on this, they may have a local ordinance that requires more, or may require other forms of protection.

Pipe must be coated to protect aganst corrosion (galvanized pipe is NOT a form of protection). You will need to talk with your local code offical to determine what they accept in your locality (depends on soil types and water tables, etc.)

You will be required to pressure test the installation in the presence of the code offical before you backfill the trench.

I would talk with your local code offical FIRST to determine if this type of job is permitted without the use of a licensed plumber.

If it is not, you could do the bulk of the work and have a plumber come in and review your work and run the final tests & hookup. Would save money and ensure you still get a safe installation.

Also, you would buy the piping from him, and he could cut the pipe to length and thread the pipe for a small fee. (You do not want to do this yourself.)

For your own safety, I urge you to consider consulting a licensed plumber in your area to buy the and thread the piping, and to review your work and make the final hook up. A small price to pay for your safety and to make certain everything is done correctly; while still saving the bulk of the costs in the project.
 
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Old 01-23-04, 04:21 PM
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I know you have good intentions.

You are over your head and don't even know it. The meter is going to be the constriction on this line.

You need to talk to several people. A licensed gas fitter who will contact the gas company and you local building department to get any permits if any are needed.

You are looking at an elevated pressure system with the gas meter you have and existing lines. There are many things to look at.

One question you need to answer from your gas fitter is what else do you plan on operating while the generator is running.

If your answer is everything...now it just got interesting.

Usually, an emergency or backup generator is ran with minimal other items operating.

Good luck with your project, take our advise into consideration with your project.

More questions, comments; ask in this thread and someone will answer them.
 
  #5  
Old 01-24-04, 02:51 PM
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My Two Cents

Hello: Rubin

Take the advice provided. It is all meant with good intentions. Hire a pro for your own safety, property protection and well being.

Other factors to consider is gas volume & load demands. Gas pressure & pressure drops as loads increase & footage distances increase. Pipe diameter is fine for that distance & load.

The current meter set assembly may not be able to handle that additional gas load demand. In that case, a meter and regulator upgrade would be required. Contacting the natural gas company is wise in this instance.

Gas ultilities are often very helpful in cases such as these. They want to sell more product (gas) and often provide the required info free. Up grades in equirement are also freely provided.

Quick phone call to the natural gas company should provide all the details needed and help required. Usually provided by customer service reps. A field service rep may be sent for on site review and assistance, etc.
 
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Old 01-24-04, 05:21 PM
rubin_l
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I have heeded the advice to get a contractor to do the natural gas installation. Though I know (hope) the contractor knows what he is doing I at least want to understand some basics behind it.

I usually get at least 2 bids. So far one person came out and told me it will be about $1,600. This seems like a hell of a lot of money to, what seems to me, run a little bit of pipe. He comes with high recommendations so I will probably fork over this wad of cash. But I don't know why it is so much.

Anyway, he said I need a split system. The gas company will come in and upgrade the meter to one with higher capacity. On the order to the gas company I am to submit, next to each appliance are two choices - low pressure or 2 PSIG.

The contractor checked 2 PSIG next to everything except the generator, which he checked "low pressure."

What I don't understand is that the diagram that came with the generator shows that it takes 11-14" water column which works out to something like 1/2 PSI and that the rest of the household goes thru a different regulator at 4-8" water column.

The generator manual specifically states that low gas pressure can damage the engine.

Why does the generator get "low pressure" from the split system but everything else goes thru a regulator that seems to give even lower pressure than 11-14" WC?

The contractor also noted down in his materials section 1" OD black steel pipe. A respondent to this thread indicated 1 1/4". Is it proper to ask the contractor about this, or just assume whatever he supplies is correct?

Thank you for your help and advice!
 
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Old 01-24-04, 06:16 PM
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Hi: Rubin

Granted. Something doesn't sound correct. Of which your local gas company should be best able to help with. Why? Because they know what their system supplies into the housepiping.

Which is normally a water colume pressure of between 7 to 10 inches of water colume pressure. The reasoning is most natural gas appliances require only 3.5 inches.

By approz. doubling the supply pressure out of the meter as a minimum, ensures pressure and volume supply into the main house piping and to all the appliances during full operation of all.

Both the pressure and the volume decline as the load demand increases. Small amounts granted but it does happen. Supply and demand at work.

7 to 10 inches ensures proper supply, providing the pipe sizing, etc is correct, and maintains the pressure in the system. Higher pressures (in lbs) will cause gas control lockup & appliance regulator damage.

The appliances have there own regulators which take the 7 to 10 inches and drops it down to 3.5 to 4.5 depending upon the appliance needs set by the factory. Read the rate plates.

Proper appliance operation depends on both gas volume supply, pipe size and distance, and maintained pressure. The gas company can best help there with there equipment.

Why the generator needs higher pressure is based on the demands and are set and required by the mfg. Deviation can cause operational problems to the gen as well as to the house appliances, since both are on the same meter.

Read the stamped in markings on the generators rating plate for the gas inlet pressure requirements. Should be on the rate plate. Also in the owners manual. Also on the gens regulator.

Contact the gen mfg. In my opinion, based on what is known here, the gen needs the higher gas pressure. 1/2 psi seems right.
 
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Old 01-25-04, 05:36 AM
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The 1 1/4" Enigma mentioned was based on "normal" low pressure gas feed.
Higher pressure really means, more gas available so you do not need larger pipes.

I see your system nothing more entailed than elevating the pressure from the meter to the tee being cut in. A regular installed on the existing line coming on into your house to drop pressure back to low pressure. Higher pressure now extends along the new run to the generator. A regulator installed just in fron of the generator to bring pressure down to it's rating.

You should be looking at a tee, some new pipe, and 2 regulators. The gas company will do their thing to their equipment to supply you the gas needed.

I would really talk to your contractor about the pressure needed for the generator you mentioned. Make sure everything is good to go when he is done.

BTW: What else do you have using gas i.e. furnace, water heater?
 
  #9  
Old 01-25-04, 11:53 AM
rubin_l
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All of your replies are very helpful and educational. I like knowing what the contractor is talking about!

Gas appliances in my house are a dryer (27,000 BTU), stove (42,000 BTU if all four burners are on max at the same time), hot water heater (75,000 BTU) and furnace (165,000 BTU). Our existing meter is rated at 250,000 CFH. I don't know how this translates into BTU, but we have had everything going at once without problems.

The gas company said that there will be a single meter with one regulator of 4-8" water column for the house and 11-14" water column for the generator. For some reason the generator's WC requirements is considered by them to be low pressure and the rest of the house to be 2 PSIG.

I still don't understand this and no one there can explain it to me, they can only parrot back what's on their response sheet. The gas techs that change the meter are the ones who are bound to know the answer, but the gas company apparently keeps them away from the phones.

I also found out that the gas company wants $500 for granting me the priviledge of buying more gas.
 
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Old 01-27-04, 12:31 PM
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Depends on the composition of the gas but typically 1000 BTU/hr = 1CF/hr. I'm wondering if you have some extra zeros in your meter's flow rate. Also a finer point but there is a difference between CFH and CF/H. One is cubic foot hours and the other is cubic foot per hour. The second is the correct measure for flow rate - the first defines a total quantity (bit like Joules which is watts Hours).

A properly designed gas system should be able to support all appliances running at full capacity and be able to maintain operating pressure at the burners. Typically for natural gas this should not drop below about 5" WC. Since the max rating of most appliances is around 10" WC the regulator should be sent to around 8.5 or 9" WC static pressure (ie with no appliances running and it really should not drop below about 6" at full load at any of the appliances to allow for a safety margin). The drop is of course a function of the pipe diameter, layout and demand but the reg needs to be set as high as possible so as to support max flow. It certainly shoudl not get to 4" WC so I'm not sure where they get the 4-8" from.

For gas anything about 1.5 PSI is considered high pressure.
 

Last edited by rav12; 01-27-04 at 04:38 PM.
  #11  
Old 01-27-04, 02:47 PM
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Once you get the gas line issue resolved and properly installed, the fun will REALLY begin!! You'll be dealing with the local electric utility, the bldg. dept. and an electrical contractor to get the generator connected!

You don't EVEN want to try doing that part yourself!! The electric utility HAS to be aware that this generator exists!! The last thing they want, and the last thing you can afford, is for a lineman to grab a wire that he thinks is dead during a power outage and get electrocuted by the power YOUR generator is producing!!!

There are VERY specific pieces of equipment that have to be included in the installation.
 
 

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