Thanks for the pointers
The house uses natural gas from a utility.
I'm pretty sure there's no regulator anywhere in the system unless it's built in to the meter which I find unlikely.
I checked around my furnace, which is also gas, and only about 5 years old, and I don't see any regulator there, but it could be built in. (I didn't install the furnace.)
Anyway, I'll get a regulator and install it.