On Wed, 19 Sep 2018 20:56:30 -0600, rbowman wrote

100# tank. Does the existing tank have a regulator?
Yes. Three are two. One at the tank and one at the foundation of the house.

My propane vendor changed the regulator on my tank from a one stage to a
two stage this spring. I'll pass on what he said as I watched him turn
off the valve. He would close it 30 degrees or so and back it out,
repeating the process gradually until the vale was seated. His theory
was old valve that haven't been turned off in years tend to leak if you
just crank them down tight.

Thank you for that hint. Sounds like what I do with old water valves.

I'm sure you know but j.i.c -- POL fittings have left handed threads. I
use soapy water in a spray bottle to make sure everything is good when
I'm done.

I had forgotten about that. I hooked them up years ago (maybe twenty?) but
haven't touched such things since long ago. Thank you for reminding me.

If you have a gas stove turn the burners on to purge the lines. No
matter how fast you are the propane tends to escape and leave some air
in the line.

Yes. Gas stoves. Gas water heater. Gas fireplace.

Good hint to open the windows and doors and then the gas lines inside the
house to prevent air in the lines.