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gas line size? and how to determine tim plz

jonny88jonny88 Member Posts: 1,139
hi,i was on a job today on long island,lady got her oil boiler replaced by a gas boiler by a reputable company of which i wont name.anyway she wants me to run gas lines for a new stove and gas heater in new is my ?.she has a 250 meter bar.of the meter bar is a 3/4 gas line which comes into the feeds a gas heater in the front of the house 16k then comes to a tee where the boiler tied into it,they increased the size to 1 inch for the boiler70k burnham steam boiler.old gas line then picks up a 50 gallon water heater.there is unions all over the place,it is an old gas line.she now wants to pick up a stove and another 16k heater.boiler company told her pipe was big enough.i need some education on this,i thought once a line was 3/4 it would stay 3/4 even if you increased its size,should an 1.25 inch line been used.also i was always taught to use left to right nipple and coupling when working back and not a union.i appreciate any not to keen on tying into the old line,what do i do?????


  • Tim McElwainTim McElwain Member Posts: 4,357
    Johnny it looks like

    you have about 217,000 BTU's total give or take a little. Using schedule 40 black pipe inlet pressure less than 2 PSI, a Pressure Drop of 0.3" W.C. and a Specfic Gravity of 0.60 a 50 foot length of  1" pipe will handle 215,000 BTU's.

    I broke down the BTU's as follows:

    16,000  heater

    70,000 boiler 1"

    50,000 water heater ( I used this as you did not give BTU rating) 3/4"

    65,000 for a gas range 3/4"

    16,000 for additional heater.

    217,000 BTUs Total

    You may want to clean up all that union business as fittings elbows, tees etc all add to the equivalent length of piping.

    If I had a drawing of a piping plan I could be more precise.
  • jonny88jonny88 Member Posts: 1,139
    edited April 2012
    thanks tim.

    i actually called you today about attending your seminar and i apreciate your quick response and help.having to ask this question means i have a lot to learn and a need to go to your seminar which i will be attending next more ?.if you have a 3/4 line for say 20' then increase it to 1 inch in effect is it true that the 1inch line will only have the capacity of the 3/4 line as the 3/4 line can only feed so much something like trying to get 30 psi out of a 20 psi compressor for example.thanks again and look forward to your class.i am goint to replace the unions with left to rights
  • Tim McElwainTim McElwain Member Posts: 4,357
    I use the longest length method

    for calculating pipe size as it gives a little lee way with sizing. It would be best to start with 1" pipe and then reduce at the equipment to 3/4" versus the other way around. If that is not however cost effective then enlarge as much of the pipe as you can. It would not hurt to even go to 1 1/4" for a manifold to the heating equipment. Keep in mind the gas range when all four top burners are on and the oven can be 65,000 BTU's or more sometimes. So the range and heating together draw down a pretty large load.
  • Empire_2Empire_2 Member Posts: 2,343
    Hey Tim?

    National Fuel used to put out a slide rule, or it's actually a dial rule to make quick calculations with all different variables.  Have you seen it? and/ or do you know if it's still available?  The 1 I have is faded and hard to read...


    Mike T.
  • Tim McElwainTim McElwain Member Posts: 4,357
    I have a Bryant

    Gas Orifice Calculator and on the other side of the calculator is a Gas Pipe Size caculator. It is an order number MP-5706B.
  • Empire_2Empire_2 Member Posts: 2,343

    Thanks Tim.  I have that 2.  Like I said, the one I am looking to replace is a round dial type of thing.  I talked to Nat. Fuel and they are clueless.  Even after I told them that their name appears in the title front of the thing.  Oh well, ....  The reason I ask is because of the gas company's office seems to have some kind of memory disorder as to their products....?


    Mike T.
  • gennadygennady Member Posts: 781
    gas line sizing

    are you a master plumber? if not, why are you working on gas lines not knowing basic gas rules?
    Gennady Tsakh

    Absolute Mechanical Co. Inc.
  • Tim McElwainTim McElwain Member Posts: 4,357
    The Engineering tool box

    gives the charts and tables but not the methods which is the same for the calculators we are talking about. To understand the different methods it requires some training.

    In some jurisdictions plumbers are not allowed to run gas lines it is only gas pipe fitters or as I am a Master pipe fitter (plumbers in my state can't install boilers or water heaters). There are also a lot of gas utilities that run gas pipe and they have no license.
  • HenryHenry Member Posts: 963

    It is all in the code books. If you are not a licensed gas fitter, you need to read NFPA54 in the US or B.149.1 in Canada and  pass your gas fitter license! it is really a no-brainier to size gas piping if your are a licensed pipe fitter! If not, you are putting the user at risk!
  • gennadygennady Member Posts: 781

    In NYC utility can run service to house and install house gas valve. this is where their jurisdiction ends.
    Gennady Tsakh

    Absolute Mechanical Co. Inc.
  • Empire_2Empire_2 Member Posts: 2,343
    ? I think the gentleman above:

    Tim I think the man above was referring to the first original post and not our conversation.  Thanks for the Defense, but I'm not worried about my qualification.  Last time I answered that, OSHA was more than satisfied.  Anyways, If I run across the dial pocket calc. I will fire off a few to your office.  They are very handy. Pocket size.

    Thanks Again:

    Mike T.
  • gennadygennady Member Posts: 781

    Yes, i was referring to the original post.
    Gennady Tsakh

    Absolute Mechanical Co. Inc.
  • HenryHenry Member Posts: 963
    DIY = OOPS

    When it comes to gas piping, both our Canadian and American codes specify a safe way to install gas appliances by LICENSED installs and NOT by DYI! What has kept the gas industry so much safer than other means of energy, was our relentless motives of making the gas industry the safest of all. We require that all concerned must be licensed and certified to do the work that they are required ACCORDING TO CODE, while the appliance manufacturer meet the most stringent requirements for safety of the supplied equipment
  • jonny88jonny88 Member Posts: 1,139
    master plumber?

    just to clarify,yes i am a licensed plumber,believe it or not on my test there is no ? on gas .i have worked on a lot of gas projects in nyc under licensed nyc licensed company from 4" all the way down so rest assured i am not a weekend warrior.i do value your concerns and input,i asked a simple ? from tim for reassurance for the homeowner.a large boiler company which i wont name did a horrific installation in her house.the lady does not have a lot of money.i know the 3/4 line is undersized.i know i have to file for a new meter bar.i know i have to remove all unions on piping one which the boiler company installed and replace with left to rights.i know im tied to this job.i know her boiler is undersized to the radiation in her house.i also know i will be attending tims seminar because i know that i dont know it all.i also no not to read to much into the title of master plumber seeing the work that is out there.and finally i know i wont be getting paid for this job but morally i cant leave it as it is,believe me i take gas work very seriously as from your coments you obviously do to.i also know that in nyc anyway a mechanical company can operate without having a master plumber license as can a piping and heating company.i do think it is ridiculous that lead wiping is more important than a gas fitting test but such is life.i also worked first hand with a nyc master plumber who wasnt so much of a master.thanks for your comments and links.
  • icesailoricesailor Member Posts: 7,265
    Gas Piping:


    Its interesting to read what "other" jurisdictions allow that are not allowed in others.

    It has been my understanding that in Massachusetts, R&L nipples and couplings were absolutely forbidden. Unions only. And I can't understand why anyone would ever want to use them. I can't even get them from the supply house unless I special order 6 at a time.

    I had a few submersible water pumps stolen by a slug who arrived where I work. I fixed his a$$ by installing a right and left 1" coupling on the pitless adapter so you needed a right and left nipple on the pull pipe to get the pump out. I never had another pump lost. For old customers that sold their houses, it drives pump installers nuts when they can't hook on to the pull pipe. I had a call from a homeowner two weeks ago from a job I did at least 20 years ago. I don't have the proper nipple on a pull pipe anymore.

    Massachusetts instituted Continuing Education four years ago with an emphasis on gas for the Plumbers. All plumbers and gas fitters take the first three hours, the second three for plumbers. The instruction is invaluable. I get mine through the PHCC of Massachusetts. Last year (Class 3) much of the gas class was on proper gas piping, layout and installation. Everything you asked was covered in that class.

    I consider my annual cost of classes to be the best money I spend. If you do the apprenticeship and do the 100 hours annually of plumbing and gas theory while an apprenticeship, AND you stay with it, you will end up a way better mechanic than you ever would be  before the classroom requirements. And few fail the test. And they did away with lead wiping before I took my Journeyman's (1967) and replaced it then with silver brazing a 3/4" wrought copper fitting. Far more useful than wiping lead.
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