Check if your pilot light is on. If it is, then there is a fault in the gas regulator and you will need to call a gas technician.
-If the pilot is off, The detailed directions are printed on front of EVERY gas regulator. - However, in general terms, turn regulator switch to OFF for 2 minutes, then to PILOT and depress for one minute, then light pilot or press clicker till it lights. Keep PILOT pressed for 2 more minutes then slowly release it. If it stays on then turn main switch to RUN or ON. Use a barbecue match (12 inch long) to light manual pilots. -If the pilot will NOT stay on, then you have a faulty thermocouple. - Not a complicated job. Call a competent handyman or gas tech.
Gas water heater has an orifice for main burner and for pilot light, if not electronic ignition.
Yes
The water continues to run into and out of the water heater. There is just no flame to heat it up.
Have you turned the control from Pilot to On? Have you increased the temperature setting?
If the pilot light is on, the heater should come on by itself. If the pilot light is off then it has to be lit. If it will not stay on, the thermocouple is bad.
By reading the directions that come with each heater as each one is slightly different
No, it is not dangerous. (Unless you are working with a water heater that is 20+ years old.) In any modern hot water heater, if the pilot light goes out a fail-safe will go off - preventing gas from leaking out. Also, there is a sensor so if there is not enough air-flow or oxygen with the water heater, it will shut off the gas.
If the tub is not getting hot water the issue is probably with the hot water heater. The hot water heater may have tripped a breaker or the pilot light went out.
Same as any hot water heater. Turn the gas valve to off.
If you have a gas water heater and your pilot light will not light, the most common problem is a faulty thermcouple. A licensed plummer can easily and cheaply fix this or you can find information to do it yourself online.
Yes, as the day goes by and the heater and as well as the light are turned on they make the water "disappear".
THERMOCOUPLE or defective gas valve