residential? commercial? new ? replacement? if its a new water heater in a new home then the easiest way is to buy copper flex's and a gas flex and make sure you have low pressure gas at your gas stop like around 10 to 14" water column. Make sure you have a cold shut off on your cold water line before you hook up to the water heater and in some states they require a expansion tank. One good rule of thumb is if you have a check valve somewhere around your water meter or if on a well by your pressure tank then its a good idea to put a expansion tank.
Gas heater & electric heater both are available.
Yes, your gas water heater will still distribute hot water.
Side of water heater, near bottom.
You cant
thermopile
no
instant gas
It converts cold water to hot water.
At current gas prices they cost less to use and a gas heater gives you a much greater supply of hot water on demand.
It depends on if it's a gas water heater or electric. I don't think electric makes any noise, but a gas water heater, you'll the gas ignite, and hear the rushing gas from the burner.
Gas not turned on to water heater. Gas valve on water heater not set to pilot setting. Faulty gas valve. Igniter for lighting pilot not working.
You need a qualified tradesman