Someone I know wants to get rid of their tankless system and go with a standard gas hot water heater. Do you just pull the coil on the burner and put a plate on it?
If it is an immersion coil, you don't have to do anything with it other than disconnect the piping. If it is a direct fired coil then you have to remove it, and seal its mounting opening.
The boiler is an American Standard (very old), gas-fired forced hot water. He's running out of hot water and wants to install a 50 gallon gas-fired hot water heater. He will be replacing the boiler shortly. I suggested going with a storage tank (superstore) on a separate zone. No venting and they seem to work reasonably well. He wants to go with the separate h.w heater in case the boiler goes down.