Plumbing in the Home/Gas Meter and Piping
QUESTION: Hi Jay,
I have an inch gas pipe but looking at the gas meter, the little short pipes coming in and out of the gas meter to feed my gas piping seems to be smaller than my inch sized gas piping system. Am I seeing this correctly? If so, does this reduce the amount of gas to say 3/4 sized piping overall? I took some pictures so you can see, please see the hyperlinks below.
Also, a general question is, for the tables that show how much gas / BTU is available for gas pipe size and length, I understand that we start performing these calculations from the meter. Why don't we start the calculations from the street? What if the 1 inch pipe from the street travels 200 feet to get to my meter and so wouldn't I have less gas available?
ANSWER: Thomas, Last question first. The meters have built in regulators that reduce the pressure to about 3 or 4 ounces. You might have a 6" or larger line prior to the meter with significantly higher pressure.
Your photo shows what we call a "meter set" this is actually part of the meters design and a system that percents pilferage and is proprietary to the meter manufacturer. For the average residence, these meters are capable of suppling more than enough fuel for all your appliances.
You are correct in that length of runs effect supply. Most newer installations bring 1" in from the meter then reduce to 3/4" and 1/2" branch lines. Keep in mind, residential water heaters, furnaces and boilers all are fed with 1/2", clothes dryers and most stoves are fed with 3/8" pipe. So unless you live in a 6000 sqr. ft home or large you should be fine. If you are having trouble now, a manometer can measure gas pressure at all the appliances. Your gas supplier can up the pressure if it is necessary but is is very seldom necessary.
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QUESTION: Jay, I'm considering upgrading from oil to gas furnace and replacing the old water heater with a tankless, which presents concern since ill have around 500k btu need total for all appliances. According to the chart, a one inch pipe is minimum requirement to feed the gas system, and so that's where my concern rose when I saw that smaller than one inch pipe on the gas meter set. In your opinion, it sounds like this is part of meter set design and not an issue. Is that correct?
I saw your comment regarding testing gas pressure with a manometer. Is there a device that can measure gas capacity / btus available at the appliance?
Thomas, since you are converting to natural gas from oil, your best bet is to contact the gas supplier and let them know your plans and requirements. They will more than likely come out to you home and assess the piping, pressure and capabilities of you current gas lines. 500k btu about 30% more than the average home but I it is still within the limits of you meter. The length of the runs as well as the sizing is important. I would replace the pipe from the meter to the first appliance with 1" black steel pipe then proceed to the next with 3/4" and and only the drops to the actual appliance is where I would reduce to 1/2". (All dimensions are inside diameter)