I'm putting in a 400k Natural Gas Heater in MA. Gas company is coming in to replace my meter. I've gotten 2 quotes from plumbers for running the line. Both want around 2k for a 70' line. One though is using a flexible line (I'm guessing PE of some kind?), the other is using rigid (guessing coated copper or black steel?). Not sure the exact materials.
What's the preferred material for a natural gas line for a pool heater?