Your water heater is one of the single most expensive components of your plumbing system. It costs a lot of money to buy it and it costs more money to operate it. If your water heater isn't working properly it can make your life miserable. Unless you really like cold showers it is a big deal when your water heater has problems.
When To Call A Plumber
This is a good time to talk a little about when it is appropriate for you to fix things yourself and when you should probably go ahead and call a plumber. Water heater problems are a good example of when this choice is important.
If you water heater itself is leaking, as opposed to the piping connected to it leaking, this probably means that it needs to be replaced. It is virtually impossible to repair a leaking hot water heater. If you can't confidently say you know how to install a water heater you really need to use caution.
A water heater replacement raises a lot of safety concerns and there are some fairly technical skills needed to do the job right. It is usually better to call a licensed plumber if yours needs replacing. Licensed plumbers know how to install a gas water heater without creating a potentially dangerous situation (and how to install electric water heater without getting electrocuted in the process).
You Can Do It!
On the other hand, if you have a non-leaking water heater and no hot water, you can often correct that yourself without calling a plumber. You don't need any really technical skills to learn to troubleshoot water heaters, just a little common sense and patience.
The first good news is that, although the trend is toward more economical water heaters, the basic operation and controls haven't changed much over the years. So some basic knowledge will allow you to troubleshoot water heaters of almost any age or manufacturer.
Gas or Electric?
There are two main kinds of storage water heaters (we won't get into tankless models here): gas and electric. This indicates what sort of energy source is used to heat the water.
Gas Water Heaters
Gas water heaters use natural gas (and sometimes LP) to fuel a burner which in turn heats the water sort of like a pot on the stove. They have only a few components that control whether or not you have hot water.
The first thing to check if you have a gas water heater and no hot water is whether or not you have gas. I know it my sound silly, but I have gone to many homes only to find that the gas had been turned off for one reason or another. If you have a gas stove see if it works. If not check your meter to make sure it's on.
If you have gas, the next step is to check your pilot light and, if it's out, try to light it. The lighting instructions are usually right on the water heater. If your gas has been off it may take a while for the air to bleed out and the gas to get to the pilot, so be patient.
The Thermocouple
If your pilot won't light, or won't stay lit, the thermocouple may be the problem. This looks like a copper wire coming from the control box on front of the water heater and going down to where the pilot light should be. It has an enlarged tip at the pilot end.
The thermocouple is positioned with it's enlarged end in the flame of the pilot. This heat from the pilot flame causes a tiny electrical signal to be sent to the control valve, telling the control valve that there is a flame present so it's OK to let the gas through to the main burner when the thermostat calls for heat. . You can change a thermocouple on most water heaters with only a small adjustable wrench. Just make sure that the bulb end is securely positioned in the pilot flame. You can get a new thermocouple at most hardware stores for under . This will usually correct a pilot light problem.
On more recent water heaters, the combustion chamber may be sealed. If you have one of these there will usually be a small inspection window you can look through to check the pilot. You may need to call the manufacturer to get a complete pilot assembly and new cover seal in order to repair these models, but the procedure is still pretty much the same once you get the parts. These parts are usually covered by the manufacturers warranty.
The Gas Control Valve
If you are sure you have gas, and replacing the thermocouple doesn't fix the problem, the gas control valve is about the only thing left to check. This is a fairly major repair so if you aren't very comfortable working with gas connections you may want to call a licensed plumber for this.
Electric Water Heaters
Electric water heaters use, you guessed it- electricity, to heat the water. If your electric water heater isn't working the first thing to do is check your breaker or fuse box. Many electric water heaters also have a separate disconnect box at the water heater, check this too.
If you are sure you have power, the problem is either your heating elements or thermostats. Most electric water heaters have two of each, upper and lower. In order to check or replace a water heater element you will have to turn off the breaker serving the water heater circuit and remove the access cover on the water heater. At this point you might get lucky and find the easiest way to fix an electric water heater.
The Reset Button
Many thermostats have a reset button which can sometimes be pushed to reset the circuit and get the water heater working again. To find it you may have to carefully remove any insulation covering the thermostat. If the reset button has been tripped you should be able to hear and feel a definite click when you push it. If you think it was tripped, put everything back together, turn the power on and check for hot water in about an hour.
If the thermostat can't be reset you will need a voltage meter or continuity tester before going any further. There's not room in one article to cover electrical diagnostics but you can perform a simple continuity check on the elements to make sure they make a complete circuit.
The Heating Elements
First, make sure the power is off to the water heater! Then locate the heating elements. The elements will have two wires connected to each one and will either have a big hex nut where they screw into the tank or will be fastened to the tank with a bracket and usually 4 bolts. After confirming that the power is indeed off to the water heater, remove the 2 wires from the element and check for continuity. If there is not an intact circuit between the two terminals on the element, it is bad.
If one or both of the elements is bad it is probably a good idea to just replace them both. You will need to shut off the water and drain the water heater to replace the elements. If they are the hex nut style, you may need a special socket. You can usually find these tools where you buy the elements. Make sure the water heater is completely full and all air bled from the system before turning the power back on or you will ruin the new elements by "dry firing" them.
The Thermostats
If the elements are OK and don't need to be replaced, it is probably the thermostat(s). It is a good idea to replace both thermostats if there are two, they are fairly inexpensive. Just remove the wires, connect the new one the same as the old one, put the access plate back on and turn the power back on. You should have hot water in about an hour.
Know Your Limitations!
Learning how to troubleshoot water heaters can be fairly simple but you do need to understand and be comfortable working with gas and electricity. Either one can literally kill you if you fail to observe the proper safety precautions. If you aren't qualified or aren't sure about something it is better to be safe than sorry.
