Sizing gas systems by the numbers
Look at the gas bill when you’re sizing gas systems
It’s no secret; I’m a second-generation plumber. My father, Adrian, born in 1923, lived through the Great Depression. That experience for him and most others who survived those desperate times, fundamentally changed what was important for each of them. Add the Dust Bowl of the southwest Great Plains region of the United States. Desperate times indeed.
In his 1939 book The Grapes of Wrath, author John Steinbeck described the flight of families “…hungry and restless — restless as ants, scurrying to find work to do — to lift, to push, to pick, to cut — anything, any burden to bear, for food. The kids are hungry. We got no place to live. Like ants scurrying for work, for food…”
Raised by his sharecropper parents in Midwest Texas, my father dropped out of school while in the seventh grade. Not to be too dramatic but survival was at the heart of many of the decisions his and other families were forced to make. Another body working in the fields could be that difference.
He told me his father was hard man, whipping children who didn’t pick their quota of 100 pounds of cotton for the day. His opportunity for escape came in 1940 when he went into the Civilian Conservation Corps and was stationed at Estes Park, Colo., at a very cold 11,500 feet. He applied for a job inside (where it was warm) as a cook.
In 1942 his oldest brother Bill, who had left Texas earlier for San Diego, invited him to join him in the paradise of Southern California. They “hot bunked” while working a succession of jobs, finally ending up at Rohr Aircraft working on PBY seaplanes.
In March of 1943, Adrian received notice from the Dallas Draft Board to report for military induction.
He told me that with insufficient funds he didn’t know how he was going to get to Dallas. He related how his girlfriend at the time took up a collection from others at the PBY factory. He was stunned and felt undeserving of their generosity. Perhaps that was one reason he was so generous in helping others he met along the way.
He returned to Dallas, was sworn into the Navy and then transferred to the Great Lakes Naval Training Center in Illinois, where he received four months of basic training. He was then transferred to Norfolk, Va., where he boarded the U.S.S. Merak, a refrigerated supply and cargo vessel. He spent 29 months aboard ship in the Atlantic Ocean and Mediterranean Sea.
After the war he returned home but in the spring of 1946, Adrian became disenchanted with life in Texas. He returned to San Diego because he had enjoyed his time there. Within a month he went to work for the Water Department. He married my mother Velma in September of 1947.
My father, strongly influenced by those tough times in the 1930’s, was always a hard worker and it was noticed, not just by his employers, but others he came in contact with. One in particular was a plumbing contractor who had seen him wielding a shovel while installing street services and water meters for the new housing projects so prevalent after WW II.
His name was John Holderer and he asked my dad if he would like to expand his horizons and become a plumber. He told him it would take some time and some studying but he would learn to read plans and the Uniform Plumbing Code, be able to size water, sewer and gas distribution systems and eventually become a licensed plumber. And so began my father’s journey as a plumber.
In 1960 he went in the business with his brother Cecil. They named the business Kirk Brothers Plumbing, which for some reason always sounded good to me. What didn’t sound so good was when he decided I needed something other than cartoons to occupy my Saturdays. While he seemed to enjoy the freedom the somewhat mindless digging and shoveling of dirt or getting past boulders with a pick would give him (he said it sort of relaxed him and could do it all day, remembering what his childhood offered), I abhorred it. I don’t think I was lazy, but a pick and a shovel never really fit my hands well. I’d shag fittings, cut and thread steel pipe (by hand), put on nail plates, wait at the wholesale house for the supplies we needed (eating a couple of donuts of course), make material lists, almost anything to avoid those opportunities which always seemed to include a worn out shovel, a wheelbarrow with a flat tire and a lot of sweat.
One thing that did intrigue me was when he would sit down at the dining room table with a set of plans and began making what I later learned were isometric drawings of the DWV system. When I asked what he was doing he would say, “Just watch,” so I did.
I was taking architectural drawing classes in Junior High and had hunted down a lot of those DWV fittings he was drawing and pretty soon those isometrics began to make sense to me. He went on to teach me some about water and gas pipe sizing using the 1967 UPC and this is where I, in my mid-teens, really began my journey to using the UPC.
Briefly, I began full time plumbing in 1969, began my own business in 1975 and began teaching the UPC in 1982 for a plumbing program sponsored by San Diego Community College. For the first time I really had to dig into the UPC and when I got to gas pipe sizing either my father had been incorrect or I had misunderstood, because while there was an example of gas pipe sizing right there in the UPC which used 1,100 btu per cubic foot, the language in the code never gave any btus to use for sizing. The language was and still is, that you can get the average btus per cubic foot of the gas in the area of the installation from the serving gas supplier (2015 UPC section 1215.3). So I called my serving gas supplier and guess what? It took a while but I finally got the answer I was looking for. Kind of.
Most of you know that natural gas meters record use by the cubic foot, but perhaps you don’t know that natural gas is sold by the therm, which is 100,000 btu. To do this the gas companies use a conversion figure that may vary every month. That conversion figure is determined by the btu in the gas they supply each month and can be between 800 and 1,200 btu, depending on where the gas is sourced, elevation and other factors.
Here is why I shared my nostalgia and then some gas facts. When I understood that 1,100 btu per cubic foot was only used as an example for sizing gas systems and it could actually be as low as 800 btu/cu.ft., I realized that without accurate information you or I could be over- or under-sizing gas systems while the best info for btu/cu.ft. is easily accessible. Just look on your gas bill for the conversion factor, which may be listed as therm multiplier, therm factor or billing factor. If it says 1.023 your gas has 1,023 btu/cu.ft., and that is the number you should be using, not 1,100.