I had not mentioned, but once the curbside shut-off was found, the plumbers came and went in half a day, and left behind a neater-looking installation than they found. Better yet, it's not leaking.
Some reader is going to look at the blotchy black stuff in the floor and lecture me about black mold. Wrong. That's coal dust and maybe a little fuel-oil schmutz; smear a fingertip through it, sniff and you can smell it. This house had a coal-burning furnace for years and years. At some point, it was converted to oil. Both are long-gone but, for those of you who remember neither, they're dirty fuels, and every hard-to-get-to or neglected corner of the house has a hidden freight of the stuff, especially the basement. The plumbers were working right next to the main floor beam and a crawl space opening, and the longer they worked (as water dripped), the more black, oily dust drifted down and the worse that floor looked. I'll be mopping it later today.
* Or is that 1"? Inch and a quarter? Whichever; the kits aren't cheap and the experience to use one on ancient pipe about seven feet above floor level and crowded by a big beam and the gas line is even more costly. Better them than me, and better the learning takes somewhere other than in my basement. --Speaking of experience, I've got unscrew a couple of aerators and remove the calcium deposits they've collected in the wake of the plumbing work.
2 months ago