I need to replace my water heater and want to install a larger one and I noticed that the larger heaters require more gas pressure. Currently using an 80 L heater and want to replace with a 114 L heater. The specs show the 80 L needs 1.76 kpa and the larger needs 2.74kpa. Is anyone using a 114 L or larger heater or happen to have any idea how much pressure comes from the gas tanks?