Tankless water heater manifold system

A method of assembling a hot water heating system, the method comprising:

• mounting a spine to a floor or wall, the spine including:
• two or more coupling areas for coupling a water heating unit to the spine, each of the coupling areas including a cold water manifold outlet, a hot water manifold inlet, and a fuel manifold outlet,
• a cold water manifold comprising a cold water manifold inlet fluidically coupled to the cold water manifold outlet of each coupling area,
• a hot water manifold comprising a hot water manifold outlet fluidically coupled to the hot water manifold inlet of each coupling area, and
• a fuel manifold comprising a fuel manifold inlet fluidically coupled to the fuel manifold outlet of each coupling area;
• fluidically coupling the cold water manifold inlet to a cold water supply source;
• fluidically coupling the hot water manifold outlet to a hot water supply source;
• fluidically coupling the fuel manifold inlet to a fuel supply source;
• and
• coupling two or more water heating units to the spine, each of the water heating units coupled to one of the coupling areas.