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Will I need dedicated NG gas pipe for portable generator ??

Hen
Hen Member Posts: 56
Hello.  I expect to get a tri-fuel portable generator rated for 8,000 W, for home back up in case of power failure.  I wonder, if a contractor will need to run a seperate pipe from the meter, or should they be able 'to tap' into one of the existing tees.  There are two "available??" plugged tees, one on a 3/4" pipe and one on 1/2" pipe. Right now, I have four NG appliances: a steam boiler (in 150,000 BTU), a water heater (in 32K BTU), a dryer,  and a range/oven on the second floor. The boiler has a dedicated 1" pipe. Then there is a 3/4" pipe from the meter which 30' into the basement has a tee and an offshoot  goes upstairs (range/oven). Same 3/4" pipe almost immediately downsizes into 1/2" pipe that goes to the water heater and continues to dryer. Question pls.: will they be able to just 'tap' into one of the tees, or would that starve the other appliances? Thank you. Hen.

Comments

  • furnacefigher15
    furnacefigher15 Member Posts: 514
    Portable

    Not very portable if you need a gas line.



    Sounds like a permanent standby. If that's the case, then yes a dedicated gas service strait to the meter is best.



    But that is just the beginning. Do yourself a favor and include a qualified gas fitter, and an electrician on the project.
  • lchmb
    lchmb Member Posts: 2,997
    The

    only way to answer that is with an on site survey.  Someone familiar with NG will need to measure your length's of run and size all of your lines based on the BTU load. Without the information needed you are only guessing and that can/will lead to problems. As was already mentioned, get a gas fitter in to go over your system..
  • Hen
    Hen Member Posts: 56
    It's a portable gen

    It's a portable, meant to be stored away when not in use. I understand they can run an NG gas pipe and install a shut off valve plus a 'quick connect/disconnect' fitting'.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Many times depending

    on the load the local gas company will need a separate meter with increased gas pressure available to handle the start up of the generator. Otherwise a dedicated gas line run directly to the generator from the meter and over-sized is the best bet, otherwise when it starts up it will pull down gas pressure in the rest of the system and pilot failure could occur.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Many times depending

    on the load the local gas company will need a separate meter with increased gas pressure available to handle the start up of the generator. Otherwise a dedicated gas line run directly to the generator from the meter and over-sized is the best bet, otherwise when it starts up it will pull down gas pressure in the rest of the system and pilot failure could occur.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Many times depending

    on the load the local gas company will need a separate meter with increased gas pressure available to handle the start up of the generator. Otherwise a dedicated gas line run directly to the generator from the meter and over-sized is the best bet, otherwise when it starts up it will pull down gas pressure in the rest of the system and pilot failure could occur.
  • Bob Harper
    Bob Harper Member Posts: 923
    gas piping to generator

    Your first consideration in location. Place the unit far enough from any occupied buildings. Check with your codes and standards then double that distance. You don't want carbon monoxide entering buildings and most people grossly underestimate how far away they need to be. That far of a gas run will probably need a 2 psi system. Talk to your utility about installing 2psi at the meter. One leg can branch off into the back yard where a second medium pressure regulator can reduce the pressure to the appliance's rated inlet pressure. Be sure to plan on a sediment trap and shutoff upstream of the regulator, another trap downstream, and clearance from your regulator vent 3ft from any source of ignition. That means you cannot mount the reg. against the generator unless you route a vent line away from the unit and attach a special vent screen on the discharge.

    The house will then also need a medium pressure regulator with the upstream shutoff and traps. Then, you should have adequate gas under full load. Once installed measure your inlet pressures under full load and perform lockup test for MP regulators. Test for gas leaks and perform combustion analysis on all appliances and you're done!
  • Henry
    Henry Member Posts: 995
    Gensets

    Most if not all generators under 20Kw will run on 7 inch pressure. Larger units require 14 inches and those above 40Kw do require 2 PSI. We have a lot of installs in wealthy residential areas that have 50 and 60Kw. We ask the utility to replace themeter allow 2 PSI. The pipe sizing and run for your 8Kw will determined by your licensed gas fitter.

    In our B149 Canadian gas code, we do NOT allow for drip or sediment legs on outdoor gas piping. Any moisture or oil trapped in the cap will freeze and break the cap! As well, any gas piping going up verticaly, does not need a sediment trap or drip leg. The rules regarding "source of igniton" is the actual source, in your case the EXHAUST! You can mount a regulator with a genset, on it, attach to it, if it is 3 feet from the exhaust.

    If you follow the certified instructions of the manufacturer and local municipal bylaws, you will find your ideal location for the genset. Most bylaws have a decibel rating whithin 3 feet of the property line. You fill find the decibel rating for your unit in the manufacturers website.

    Advising a property owner who is NOT licensed, is not a good idea. A licensed gas fitter with generator experience is what is needed. The most dangerous problem in the gas industry is the D.Y.I people who have received tips from someone.



    Henry

    Voting member B149, B149.2, .3, .4, .5
  • Hen
    Hen Member Posts: 56
    Generator has arrived

    The generator has arrived.  Will try it out with gasoline first, then with a 20# tank of propane. As for the NG, I cannot find gas fitter in the Yellow Pages for my area.  Will continue looking for NG competent pro.  Thank you for all the responses, advice and cautions, to date. Happy New Year.
  • Henry
    Henry Member Posts: 995
    edited January 2012
    20 Lb tank

    Check this link for using a 20 Lb tank:

    http://propane-generators.com/portable-propane.htm#Boiling_Point



    Using our tank requirement charts in our propane code, a 20 Lb tank will not work. Your unit of 8Kw consumes about 139,000 BTU. At 32F a 115 Gallon tank is required. From 0F to -10F a 240 gallon is required and below taht a 400 gallon tank.
  • Hen
    Hen Member Posts: 56
    CFH labeling on gas meter

    I am wondering about CFH label on my  NG gas meter: "275 CFH". Does that mean that the total BTU rating of all my appliances, if used at the same time, cannot exceed 275,000 BTU?

    Also, I noticed that gas enters the meter via a  1/2"  'Z' - like fitting and exits the meter via identical 1/2" fitting. Should those fittings, especially the outlet fitting, not be larger? At least as large as the largest pipe that follows ?  ( 1" pipe runs from the meter to my gas boiler and also  3/4" pipe runs from the meter to several other appliances).
  • Hen
    Hen Member Posts: 56
    using small propane tanks for portable generator

    I had surfed the site and bookmarked  it before. If I read it correctly, the gen should work with two 20# tanks tied together in tandem. The site actually has a device to connect the two 20 pounders.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Yes the 275 CFH stands for

    the fact that the meter which measures flow in CFH (Cubic Feet Per Hour) will allow 275 CFH to pass through roughly 275,000 BTU's. So the total load on your gas system can't exceed that. They can (gas company) by the way install a larger meter and change the near meter piping and meter bracket to pass more gas.



    You must also account for what system is in the street as far as gas pressure. Older inner city piping systems are low pressure usually less than 1/2 a pound pressure, measured in inches water column (27.7 inches = 1 pound pressure). If you have a high pressure system in the street it is a pounds system and can be as high as 90 to 100 pounds pressure. That makes a difference when adding a higher load appliance to your system. You can tell what you have by the piping to the meter, if the pipe comes from the street right to the meter with no regulator ahead of the meter then it is low pressure. The regulator reduces pounds pressure to inches water column (usually 6 to 7" W.C.).
  • Hen
    Hen Member Posts: 56
    No regulator before gas meter

    Hi Tim. There is no regulator before the gas meter. (The house is perhaps seventy years old). I will try to get the gas company to come out and see what they have to say 'bout a pipe for a portable gen.

    Other markings on my meter: " MAXOP 5 lbs "....." CL250 "..........

    " TEMP. COMP 60*F BASE "......  What do all these stand for? Thank you.

    (* mark for a degree; I don't have mark for a degree on my computer)

    Also, those 1/2"  fittings immediately in and out of the meter, that I had mentioned in prior post,  what effect would their 1/2" size have on the piping and pressure downstream? Two long pipes that come out from the meter outlet fitting are: first is 1" and the second is 3/4" diameter.  Thank you.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Gas Meter

    There is no regulator before the gas meter. (The house is perhaps seventy years old). THAT SAYS YOU ARE ON LOW PRESSURE SO TYPICALLY THAT MEANS ABOUT 7 TO 10 " W.C. - LESS THEN 1 POUND.



    Other markings on my meter: " MAXOP 5 lbs "....." CL250 "..........

    " TEMP. COMP 60*F BASE "......  What do all these stand for? Thank you.MAXIMUM OPERATING PRESSURE IS 5 POUNDS FOR THAT METER AT 250 CUBIC FEET OF GAS. THE METER WILL ALWAYS MEASURE GAS FLOW FOR ACCURACY AS THOUGH THE OUTDOOR TEMPERATURE IS 60°. THIS IS DONE BY USING A BI-METAL INSIDE THE METER.

    (* mark for a degree; I don't have mark for a degree on my computer) ° CAN USUALLY BE ACQUIRED BY PUSHING "NUMBER LOCK" ON THE KEY BOARD AND THEN HOLD DOWN "ALT" KEY AND ON THE NUMERIC PAD DO 0176. DO NOT FORGET TO GET OUT OF "NUMBERS LOCK" AFTERWARD.



    Also, those 1/2"  fittings immediately in and out of the meter, that I had mentioned in prior post,  what effect would their 1/2" size have on the piping and pressure downstream? THE  METER BAR WILL NOT AFFECT YOUR DOWNSTREAM PRESSURE AS LONG AS THE PRESSURE IN THE STREET IS GOOD.

    Two long pipes that come out from the meter outlet fitting are: first is 1" and the second is 3/4" diameter. I WOULD IMAGINE THE PIPING TO YOUR EQUIPMENT WAS SIZED CORRECTLY AT THE TIME IT WAS INSTALLED AND AS LONG AS THE GAS PRESSURE TO THE EQUIPMENT DOES NOT EXPERIENCE ANY PRESSURE DROP IT IS OKAY. THE ONLY WAY TO KNOW FOR SURE IS TO CHECK THE GAS PRESSURE WITH A "U' GAUGE (MANOMETER) OR A DIGITAL MANOMETER. MOST PROFESSIONALS WHO DO THE JOB CORRECTLY WILL CARRY THOSE AND CAN CHECK THAT FOR YOU. 
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