[QUOTE=Rick]
There are basically three things that can go wrong with a gas water heater.
- Bad Thermocouple
- Bad Unitrol (the box on the side of the water heater that controls the gas flow and water temp
- Leaks
First off take the little door off the bottom of the heater below the unitrol. This is the access to the pilot light. There may be two little doors one inside the other. Is there standing water in the lower pan or excessive rust on everything? If yes, stop you have a leaky heater, replace it.
Is the pilot lit? If yes, the unitrol is bad, the thermostat (on the unitrol) is set too low, or to the pilot position If no try to light the pilot* (instructions are printed on a label on the side of the water heater) Note: you will have to hold the override button for about a minute before the pilot will stay lit.
Did the pilot light and stay lit? If no, it is either a bad thermocouple, or a bad unitrol. Murphy’s law of water heater repair is which ever one you guess it will be the other one. Thermocouples are cheap, and easy to find. Unitrols are expensive and hard to find. Ask me how I know this.
If yes, does the burner come on? If no, bad unitrol.
*You did pay the gas bill didn’t you?
[/QUOTE]
I’m going to add to this: The dip tube. Now, if you can’t get any hot water at all, it’s not the dip tube. However, if you get a little bit (say 1 - 5 gallons) of hot water, and then it goes cold, it’s probably the dip tube.
They are simple to replace. The dip tube makes sure that the incoming cold water is put into the tank way at the bottom, so it pushes the heated water out the top. If it’s broken, it will allow the new cold water to come in right at the top of the heater. Since the inflow and outflow pipes are very close together, you only get a tiny amount of hot water out before the cold water is all sitting right on top and being pulled out the outflow pipe.
Also, not all water heater pilots require holding a lit match or anything. I recently had to buy a new one because my old one was leaking, and it comes with a push-button igniter and the whole system is sealed off and you look through a litle window to see if the pilot is lit or not.
Do go down to your water heater and check it out. The instructions on re-lighting the pilot are written right there, see if you can follow them. You have to physicaly hold the button down in order for gas to come out, so the chance of you blowing up your house is minimal.