The water heater burner may not stay lit due to issues with the thermocouple, gas supply, or ventilation. It is important to check these components and ensure they are functioning properly to maintain a consistent flame.
THERMOCOUPLE or defective gas valve
Low coolant level? Cooling system airbound? Bad thermostat? Water pump not circulating coolant? Heater control cable not working?
Have you turned the control from Pilot to On? Have you increased the temperature setting?
You might have to try pushing the button for longer, or you might have a bad thermocouple.
check these in order, thermostat,heater coil,water pump,oil pump and main crank bearings.
Check the starting directions, most gas heater pilots must have the button depressed for more than 30 seconds. If this does not work there is a problem with the regulator.
Because it has no food and water so it wont stay alive
you have a bad heater core
dirty carb bowl or water in the carb
too dense to float
More than likely you will not have heat being the water wont be circulating through the heater core , When the hot water passes through the heater coil the air passing through the heater coil makes heat blow out the vents when you have selected a heat setting on your controls.
The flame detector on the pilot assembly is probably defective. If you do not know how to fix this, call you gas supplier and have it repaired.