Ariel wrote:
I have a very slow gas leak in my house that I simply can't find.
The gas is leaking at a rate of 1.7 cubic feet per day (0.071 cubic feet
per hour) as measured by the meter.
I don't smell gas anywhere, and I have looked at (sniffed actually)
every joint I could reach, and nothing.
My question is how sensitive of a detector would I need in order to find
this? I have seen detectors with ppm sensitivity ranging from 50 to
2000. Obviously price goes accordingly, how sensitive of a detector do I
need?
And realistically speaking, how bad of a leak is it? I know that any
leak at all sounds scary, but a leak so slow that you can't smell it is
not a fire hazard as far as I know, but it does waste gas.

Why worry about finding it yourself? Call the gas company, and tell 'em "my
gas appliances are all off, but the meter is still running". That should get
some folks who know what they're doing out in a jiffy -- the gas company just
hates the publicity when a house blows up.