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Gas Pressures

Tim McElwain
Tim McElwain Member Posts: 4,608
This question keeps coming up in different postings as to what pressure your local natural gas utility is guaranteeing you?

It used to be when I worked for the utility we gave 7" to 10" W.C. as an answer. I am now hearing 4" W.C. pressure. Be advised on demand water heaters, Mod/Cons etc can not run on those low pressures. So that limits what areas those can be installed.

I had a recent job for a church that needed 1,250,000 for the boiler the utility could only give us 5" pressure so we had to install a three inch pipe line to the boiler.


  • SWEI
    SWEI Member Posts: 7,356
    7 to 11 is what they quote here

    and zero willingness to install 2# systems after the latest corporate acquisition.  Had to weld up a 4" main on a job last year thanks to that...
  • Bob Harper
    Bob Harper Member Posts: 1,026

    Since most mfrs. design, construct, test and list their appliances to a certain minimum inlet pressure under full load, I use this against low inlet pressure issues with utilities. I simply take the rating plate data, which clearly states a minimum inlet pressure and show the utility. When they balk, I send them a certified letter return receipt informing them they will be held liable for any operational problems not limited to but including delayed ignition, flame rollout, sooting, carbon monoxide production, premature failure of appliance components such as the heat exchanger,  low heat output, low operating efficiency, adverse emissions, and inability of the appliance to perform as tested and listed. Therefore, the local AHJ or Fire Marshal, who gets a Cc of this letter, is requested to Tag Out/ Lock Out the building as being uninhabitable and immediately hazardous to occupancy and in accordance with the International Fire Code. In the case with rental occupancies, the tenants will then have a clear case against the landlord and utility for marketing an uninhabitable space due to the hazards this condition presents. I further state that now being so informed, should any incidents result in personal injury, death or major property damage, somebody at the utility may face not only civil charges but criminal charges for reckless endangerment, gross negligence, and fraud for not providing adequate fuel while posing as a fuel supplier.

    The problem usually gets resolved immediately at no cost to the client.
  • bill_105
    bill_105 Member Posts: 429
    Whew, holy cow Bob

    Now I don't mean to touch on your legal approach but you forgot the ever popular pain and suffering;)
  • NYplumber
    NYplumber Member Posts: 503
    Reverse calculating

    Great post Tim! I have a feeling our latest emails prompted you to post this.

    Any way to calculate off the given pressure what size to pipe the gas supply line?
  • NYplumber
    NYplumber Member Posts: 503
    Town size

    Bob, thats all great, however that wont work in NYC. May work in a small town, however I cant see National Grid raising the pressure to a whole block for one customer.

    Its too unfortunate that todays gas guys know ziltch. Had one two days ago tell me that the zones were piped wrong. I replied that 1, hes wrong and 2, I wasnt the installing contractor.

    Two clowns from the service department came to diagnose the issue. One tells the homeowner to test PH, and the next says "nah". Needless to say the customer cancelled his service contract the same day.

    Like Tim stated in the original post, many of these issues can be eliminated if the proper equipment is installed with the given gas pressure that is available.
  • Tim McElwain
    Tim McElwain Member Posts: 4,608
    I recommend for heating a minimum pipe size of 1"

    having said that find out what you local utility can guarantee you. Keep in mind and this is what I was taught when I worked for the utility any measured pressure less than 4" W.C. to the heating equipment you have to leave it shut off for safety reasons.

    If you can get hold of one use an accurate pipe sizing calculator ( I have an old one from Bryant) size the pipe to the pressure the utility says they can give you.

    Just as a point about knowledge from fuel providers there seems to be a real lack of knowledge from their employees. I was at a recent meeting and a speaker from a provider was teaching all the contractors in the class about gas pressures, metering etc. I had to get up and leave as all the mis information was making me nervous. When I get nervous I tend to stand up and say things that get some folks upset. Better to leave than get into a pissing contest with the "gas experts". It is up to the contractor to have the knowledge today do not rely on anyone else, remember when the lawyers show up they will finally come down to the installer/service tech.
  • Tim McElwain
    Tim McElwain Member Posts: 4,608
    I hear you Bob Harper

    I wish a strong stand such as that would work. Perhaps with a small utility they may try to help the contractor somehow.

    The big guys are not going to boost pressure anytime in these areas for several reasons. The most important being that increased pressure in these old cast iron mains can increase leak calls. Most of the bell joints and joints all leak, more pressure in the lines makes it worse,

    We have so much gas equipment going in it is impossible to keep up. If the customer has gas in the house the installer just goes ahead and installs gas equipment. If the meter is sized large enough already for the load and the pressure in July and August is good install away. Come January you will find out if your calculations are correct. We also have boilers and furnaces being changed by some friend or relative on the weekend and nobody knows anything about that customer being added to the already strained infrastructure.

    Here I go again, the professional contractor who does everything right ends up sometimes the loser in these situations. He has a license, he pulls permits, he does a professional job. The job he just put in was to the last house on the street to get gas. Come January NO PRESSURE due to overload of the main pipeline and extreme demand in very cold weather. UPSET CUSTOMER blames the good guy!
This discussion has been closed.