Advocate Master Plumbing has been performing water heater installation, repair and replacements for over 25 years. In this time we’ve provided all manner of water heater services. We recognize that not everyone is in the best financial situation when a water heater repair becomes necessary. For this reason, this water heater troubleshooting and DIY page has been written. Some of you are skilled and capable of DIY water heater repairs. But be cautious. A hot water heater is a dangerous plumbing appliance. It is our recommendation that you always hire a master plumber for all your water heater repairs. But it’s also good to be informed about what options there are regarding water heater repairs, installation and replacements as well as water heater services.
Feel free to jump ahead by clicking one of the links below
- How does a gas water heater work?
- How does an electric water heater work?
- Gas water heater parts
- Electric water heater parts
- Common water heater repairs
- How to light a gas water heater pilot light
- How to clean & reset a flammable vapor ignition resistant water heater
- How to flush a water heater
- How to replace a water heater thermocouple
- How to replace a water heater relief valve
- How to replace a water heater sacrificial anode rod
- How to rebuild an electric water heater
Contrary to popular belief, you don’t have a hot water service pipe entering your home. You only have one water service pipe entering your home. It’s attached to a plumbing appliance; your water heater. That water is then heated to a set temperature and distributed throughout your home with it’s own separate hot water pipe system. Now let’s look at a standard gas water heater.
When you turn on a faucet for hot water, cold water enters the standard gas hot water heater from the top. It’s diverted to the bottom of the tank by it’s dip tube inside the tank.
Once in the bottom of the water heater tank it mixes with the existing hot water. The water heater gas control valve, a square valve at the base of your tank, senses a drop in temperature and allows gas to flow to the burner assembly. The standing water heater pilot light ignites the incoming gas to the burner assembly. It will keep the flow of gas to the water heater burner assembly on until the set temperature is reached and then shut off the flow of gas. The exhaust gases from combustion travels through the hollow center of the water heater tank and into a flue pipe at the top. These heated gases come in contact with the steel tank and transfer heat to the water. There’s a water heater flue baffle that slows the natural rise of the heated gases to allow more time to extract heat. These exhaust gases eventually flow through the flue and out your homes roof.
There are safety devices, insulation and other parts to a standard water heater. But this is basically how a water heater works. There are some fundamental differences in high efficiency water heaters such as the power vent water heater, tankless water heater and hybrid waters. But the most common water heaters are being addressed.
How does an electric water heater work?
The electric hot water heater is a bit simpler than a gas water heater. Besides the obvious difference in a heat source, the standard electric water heater is basically the same.
It’s generally accepted that the standard electric water heater is only half as efficient as the standard gas water heater. That’s because it takes more energy to create electricity than to convey gas.
When building a home an electric water heater is less expensive to install. There’s no need to penetrate your roof with a flue pipe. There’s no need for a gas source. And there are fewer safety concerns since there is no combustion, exhaust gases or pilot flame. The pilot flame is a safety issue because of stored combustibles such as paints, solvents or stored furniture and boxes.
The heat cycle of a standard electric water heater begins the same as a standard gas water heater. When a call for hot water is created by turning on a faucet, dishwasher or washing machine, cold water flows into the water heater tank from the top. The water flow continues inside the tank, through the dip tube, to the bottom of the tank. The cold water mixes with the hot water lowering the water temperature inside the water heater. The lower thermostat, mounted on the outside of the tank but inside an outer cover, senses the lower temperature and starts the flow of electricity to the water heaters lower heating element. It will remain on until the water heater thermostat set temperature is met. Then the electricity will be shut off.
The electric water heater has an upper and lower element. They never come on at the same time. And the lower element is usually the one that fails first since it’s the one that comes on and off the most. If a large amount of water is used and the upper thermostat senses a temperature
drop below it’s set temperature it will shut off the lower thermostat and then come on itself. Once it’s temperature setting is met it will allow the flow of electricity to the lower thermostat. They work in tandem because the draw of electricity would be too much for the standard home electric supply.
Gas water heater parts
There are some basic water heater parts that you’ll need to understand before attempting a gas
water heater repair. As a Lee’s Summit plumbing company my recommendation is that you allow the professionals to make any emergency water heater repairs. But it is important to understand how the professionals do it before finding a local plumber near you. These are the gas water heater parts we work with on a daily basis.
Water heater thermocouple
The most common reason for a gas water heater failure is an old thermocouple. A water heater
thermocouple holds the gas flow to the gas control valve open. It also senses the pilot flame. If the water heater pilot light goes out the thermocouple will stop holding the flow to the gas valve open.
That means your water heater won’t come on. If the thermocouple wasn’t there and your pilot light went out, the water heater gas control valve would leak gas into your home. This has been a problem with home plumbing appliances in the past.
Water heater relief valve
The water heater temperature and pressure relief valve is a safety device. It protects the water
heater from excessive water pressure. It also protects the water heater from too high a temperature. Excessive water pressure can crack a weld joint in the water heater tank. Excessive water temperature can start to boil. And boiling hot water can really build up pressure and scald someone. But that would only happen if the gas valve failed and just started heating
uncontrollably. When the water heater t&p relief valve lets water drip from the attached drain pipe it’s also introducing cold water to the tank. This cools the tank and lowers the pressure inside the water heater quickly.
Water heater gas control valve
The gas control valve is the brain of your gas water heater. It senses the water temperature inside
the tank. It regulates the temperature at which the water heater heats the water. It allows the flow of combustion gas to the pilot flame and water heater burner assembly. It shuts the water off when a safety feature dictates it. A water heater gas control valve replacement is the most
costly repair you can make. Usually age or an improperly installed water heater gas line is the reason for the failure. A water heater installation is normally the smartest option when you have a gas control valve failure.
Water heater exhaust flue
The water heater exhaust flue is the three or four inch silver pipe leaving the top of standard gas
water heaters. The flue is where all of the combustion fumes leave your home. There is also a part called the flue draft diverter. It’s the connection between the top of the water heater and the exhaust flue. It’s there to prevent air from outside blowing out the pilot light. Most of my plumbing customers believe that the most dangerous part of a water heater is the gas pipe. It’s actually the water heater exhaust flue. The flue pipe contains carbon monoxide. Natural gas and
propane gas are both quite volatile. But you can smell them. And they’re usually supplied at gas pressures below half a pound per square inch. And the gas pipe to a standard gas water heater is usually much stronger than it would ever need to be. Carbon monoxide is odorless. Your water heater is completely dependent upon convection to exhaust the combustion gasses.
Water heater dip tube
The water heater dip tube prevents cold water from going into the hot water discharge pipe without first being heated. Because the dip tube is a continuation of the water heater cold water
supply and directs the water to the bottom of the tank this is avoided. The dip tube is made of a thin walled plastic. In the mid 1990’s there was a problem industry wide with this dip tube falling apart inside the water heaters. There was a bad batch of plastic used that was falling apart in the tank. This would allow for intermittent cold water to come out of the hot water pipes. It also created a mess with plastic parts clogging water pipes and plumbing appliances and fixtures. A process of back flushing the water lines cost many plumbing customers around
Lee’s Summit and the rest of the Kansas City area. The class action suit for this paid only for the replacement of the dip tube. Unfortunately that did little for those people with plastic parts clogging their water pipes and fixtures.
Water heater burner assembly
If the gas control valve is the brains of the water heater then the burner assembly is certainly the
brawn. The water heater burner assembly is an extension of the gas control valve. It’s where everything happens. Everything that involves heating is done with the burner assembly. The only
time a plumbing customer will have to deal with the burner assembly on a water heater is if they need to relight the pilot light. Your plumber will be the only one touching it. It’s where the pilot flame, burner and thermocouple are.
Flammable Vapor Ignition Resistant (FVIR)
Since 2003 gas water heaters have been installed with a safety system called the flammable vapor ignition resistant system. The FVIR system prevents fires caused by combustible chemicals and materials being stored near the pilot flame of a gas water heater. An arrestor plate is installed
under the tank. This is a fine screen that allows air in but prevents any flame from going out.
This system has also mandated a temperature switch on some gas water heaters. The new FVIR units must have a sealed burner chamber. If there was a larger than normal flame in the burner chamber
the burner chamber cover plate would over heat. A temperature switch is mounted on the cover plate. If the cover plate gets too hot the temperature switch will stop the flow of gas.
Water heater sacrificial anode rod
Most standard water heaters are made of metal. Water and metal don’t work well together.
Especially when you have hot water. And when you also have hard water deposits, chlorine, fluoride and other chemicals our municipal water suppliers add, the water can damage a tank pretty quickly. The water heater tanks are line with enamel. But there are threaded points that aren’t lined. So the tank needs to be protected from corrosion.
A water heater sacrificial anode rod extends the life of your water heater. It does this by sacrificing the metals in it to the corrosive nature of the water. This balances the ph levels of the water slowing corrosion of the water heater tank.
Electric water heater parts
Electric water heaters have fewer parts than a gas water heater. But many of the previously mentioned parts are also in the electric water heater. Let’s look at the parts that are different.
Electric water heater heating element
The heat source for the electric water heater is the heating element. Water heater elements work on the same principle as your toaster. If you introduce a flow of electricity into a looped wire made of metal there will be a slowing of the current. This is
called resistance. Electrical resistance is kind of like friction in that it creates heat. Water heater elements make a lot of heat. When the electric water heater thermostats call for heat the heating element glows red. The heating elements are inside the tank.
Electric water heater thermostat
The thermostat is the brains of the electric water heater. There are two of them that mount on the side of the tank under the insulation; the upper thermostat and the lower thermostat. The
thermostats sense the temperature of the metal tank and call for heat when the water heater drops below the set temperature. Electricity flows through the upper thermostat first. If this thermostat is sensing a correct temperature then it allows electrical current to flow to the
lower element. If the temperature gets too hot or there is an electrical short or surge the upper thermostat has an overload switch that can be reset. Because heat rises even in water the lower thermostat generally is doing all the work.
Common water heater repairs
In this next section of our water heater DIY page we’ll discuss some common repairs. There are many different types of water heaters and even more involved and complicated repairs. But since we highly recommend you let us make any water repairs we’re going to only cover the most common repairs.
How to light a gas water heater pilot light
Lighting the water heater pilot light is one of the easier DIY plumbing repairs. It can also be scary for some of our plumbing customers. The idea of dealing with gas and fire makes the imagination
run wild. But when your water heater stops working you get pretty motivated. The step-by-step instructions to light your gas water heater pilot light are on a sticker near the front of your water heater. Follow them and you’ll be fine. If you can’t locate the instructions here are some general instructions that should match most standard tank style water heater models.
The following instructions are for standard tank style water heaters manufactured after 2003. These are the flammable vapor ignition resistant water heaters.
- The first step to relighting your pilot light is turn the water heater gas control valve knob to “pilot”. Try to be exact. There is a bit of a “sweet spot” for the button to be depressed.
- Set the gas control valve temperature setting to it’s lowest setting.
- Push down on the knob and hold. This will bypass the gas control valve safety’s and force gas through the pilot tube.
- There will be a button called the “Piezo igniter”. Press it to create a spark to ignite the gas being forced through the pilot tube. You may need to do this multiple times for the flame to start.
- Continue pressing the water heater gas control valve knob for approximately 1 minute. This will give the thermocouple time to sense the flame.
- Let go of the gas control knob and check that the pilot flame stays lit. If it doesn’t you may need a thermocouple replacement.
- Turn the gas control valve knob to the “on” position. This engages the gas control valve and it will allow gas flow through the burner tube.
- Turn the water heater gas control valve temperature setting to it’s normal setting. If the burner doesn’t come on it could be that the water temperature setting has been met. Turn up the temperature temporarily to call for heat.
- If the pilot light stays lit but the burner won’t come on then call us. It may be time for either a gas control valve replacement or new water heater.
How to clean & reset a flammable vapor ignition resistant water heater
A flammable vapor ignition resistant water heater safety system is very sensitive. Dust in the arrestor plate can create an overheating burner chamber cover plate. This can make the thermal cut-off switch shut off the flow of gas. On other models, such as Rheem, there is often a heat sensitive glass vial holding a spring loaded cap. This cap will plug the air flow through the arrestor plate. The pilot flame will eventually go out. And that will cause the thermocouple to stop the flow of gas. That will mean a water heater repair for that model.
Cleaning a flammable vapor ignition resistance system for your water heater is pretty easy. For this you’ll need a couple of damp rags, a vacuum cleaner and toilet brush or air compressor.
- Turn the gas control valve knob to the “off” setting.
- Wipe down the air intakes at the base or side of the water heater.
- To remove the dust or lint from the arrestor plate you can use a long handled brush or an air compressor.
- Sweep and vacuum around the water heater base.
- Feel the burner chamber cover plate for heat. If it’s cool reset the thermal overload switch, the little button on the burner chamber plate with two wires connected, by
pushing the button between the wires.
- Then follow the relighting instructions above.
How to flush a water heater
Hard water deposits form quickly on plumbing fixtures and appliances. But when you add heat to the water they form much more quickly. Depending on the water hardness of your municipal water supplier a water heater flush is a very good way to extend the life of your tank style water heater.
To perform this water heater service you’ll need a garden hose and possibly a screwdriver.
- Turn off the water supply valve to your water heater.
- Turn off the electricity to your electric water heater or turn the temperature setting of your gas water heater thermostat to it’s lowest setting.
- Attach the garden hose to your water heater drain valve & put the other end outside your home.
- Turn on the hot side of a 2 handle faucet on an upper floor if possible.
- Turn on the water heater drain valve. If water doesn’t come out bump the water supply valve on for a bit to blow out the blockage.
- Empty the tank completely.
- Then turn on the water supply valve to the water heater and let it blow more debris out of the bottom of the tank for a minute or two.
- Shut the water heater drain valve off and let the water fill the tank.
- Turn the faucet off on the upper floor once air no longer comes out.
- Remove the garden hose and turn the electricity back on or the gas control valve thermostat back up.
How to replace a water heater thermocouple
A water heater thermocouple installation begins with the proper tools and materials. Before beginning this water heater service you’ll need a pair of pliers or adjustable wrench, a screwdriver and some teflon thread compound.
- Turn the water heater gas control valve knob to “off.”
- Loosen the nuts under the gas control valve to the burner gas tube, pilot tube & thermocouple.
- Remove the burner cover plate screws.
- Remove any wires to the spark igniter and temperature switch.
- Remove the burner assembly.
- Remove the old thermocouple.
- Install the new thermocouple.
- Reinstall the burner assembly.
- Thread the nut for the new thermocouple in.
- Wipe a little teflon thread compound on the threads of the burner gas tube nut and pilot tube nut.
- Reinstall the burner gas tube and pilot tube.
- Install the burner cover plate screws.
- Reconnect wires to the igniter and temperature switch.
- Turn the gas control valve to “pilot.”
- Follow pilot light lighting instructions.
These thermocouple lighting instructions are general and should cover most gas water heaters. In some circumstances there may be a burner cover plate gasket that needs replacing. There may be a rubber grommet around the thermocouple that needs to be sliced with a razor knife to access the old thermocouple.
How to replace a water heater relief valve
A leaking water heater relief valve can be costly. You’re wasting gas and water. And you’re risking water damage around your water heater. When a T&P relief valve leaks it may be a sign of another problem. In which case, the water heater relief valve is just doing it’s job. That means the new water heater relief valve will also leak. So before replacing a water heater relief valve be sure to diagnose the problem correctly. This is where Advocate Master Plumbing can help.
To begin your leaking water heater T&P relief valve replacement you’ll need the right tools and materials. For this project you’ll need a pipe wrench, a pair of pliers, possibly a screwdriver, a garden hose, some teflon, teflon thread compound and a new water heater T&P relief valve.
- Turn off the water heater water supply valve on top of the tank. It should be on the cold water supply pipe a foot or two above the tank.
- If you have an electric water heater turn off the power at the electrical breaker box. If you have a gas water heater set the temperature on the gas control valve to it’s lowest setting.
- Attach a garden hose to the water heater drain valve at the base of your water heater and run the other end of the hose either outside or to the closes drain.
- Turn on the water heater drain valve. If it doesn’t have a handle use your screwdriver.
- To break the vacuum preventing the water heater tank from draining, pull up on the old T&P relief valve lever to manually open it.
- If the water heater is still not draining properly you may need to close the T&P valve lever and bump the water supply valve on for a moment to blow out any hard water deposits plugging the valve.
- Let the tank drain until the water level is just below the water heater relief valve. You can check the water level in the tank by measuring how high you can lift the garden hose before the water stops coming out.
- Turn off the water heater drain valve.
- Using your pliers, remove the relief valve drain pipe.
- Using your pipe wrench, remove the old water heater T&P relief valve.
- Holding the new relief valve in your left hand, wrap teflon tape around the threads three times. Do this in a clockwise motion starting at the second or third thread.
- Wipe a thin line of teflon thread compound on the first and second threads only.
- Thread the new water heater relief valve into the tank. Be careful not to cross-thread it. Use the pipe wrench to tighten it. Be careful not to bend the softer drain threads of the relief valve.
- Wrap teflon tape twice around the threads of the relief valve drain pipe and reinstall it. There’s no need to over-tighten it. It just redirects the water.
- Turn the water heater water supply valve on and check for leaks. If there are none remove the garden hose.
- Run water through a faucet on an upper floor if possible until all air is out of the tank.
- Turn on the power at the breaker box if you have an electric water heater. If you have a gas water heater relight your pilot light and turn the temperature setting back up.
How to replace a water heater sacrificial anode rod
Water heater sacrificial anode rods play an important role in the longevity of a standard water heater. When they have been depleted or overwhelmed by an electrical ground of hard water deposits the water heater tank won’t last much longer. A water heater anode rod installation is more difficult than it looks. They are very difficult to remove. But replacing a water heater anode rod will extend the life of your water heater.
For this job you’ll need a large socket wrench, a screwdriver, a 1-1/6th inch socket, garden hose, teflon tape and thread compound.
- Shut off the hot water heater water supply valve.
- Turn off the electrical supply to your electric water heater or turn the gas control valve thermostat down to it’s lowest setting.
- Attach the garden hose to the water heater drain valve & run the other end of the hose to the closest drain or outside your home.
- Turn on the water heater drain valve using your screwdriver if it has no handle.
- Turn on the hot water only to a 2 handle faucet preferably on an upper floor.
- Once the water has drained below the water heater anode rod turn off the drain valve.
- Remove the anode rod using your socket wrench.
- Pull out the old sacrificial anode rod.
- Holding the anode rod nut in your left hand wrap it’s threads three times, beginning at the second or 3rd thread from the end, in a clockwise motion.
- Wipe teflon thread compound on the first and second threads.
- Insert the new sacrificial anode rod into your water heater and tighten appropriately.
- Turn the water heater water supply valve back on.
- Shut the faucet off on the upper floor once all air has stopped flowing from it.
- Remove the garden hose
- Turn on the electrical supply or turn the gas control valve thermostat.
How to rebuild an electric water heater
When your electric water heater isn’t putting out as much heat or just plain stops heating it’s time for a DIY home plumbing repair. It may be as simple as resetting the electrical breaker and/or compressing the upper element reset switch. This is a red button you just push. Otherwise, your electric water heater repair is going to be much more involved. Unless you’re very experienced with testing electricity I’d highly recommend completely rebuilding it. This will involve an upper and lower heating element replacement and an upper and lower thermostat replacement. It sounds much worse than it actually is. But because of the amount of time involved in draining a water I’d recommend replacing all the components mentioned. Electric water heater parts aren’t that expensive. And it would feel awful to go through all that work to find out you should have replaced something else.
For this DIY plumbing repair you’ll need some tools and meterials. The tools you’ll need include a long phillips head screwdriver, a multi-screwdriver, an electric water heater element socket wrench and a garden hose. The materials you’ll need are an upper and lower electric water heater element, an upper an lower electric water heater thermostat, teflon tape and teflon thread compound.
- Follow the instructions above for flushing a water heater including turning off the water heater electrical breaker.
- While it drains you can be removing the upper and lower panels covering the thermostats and heating elements using your multi-screwdriver.
- Remove any insulation and any plastic covers on the thermostats.
- At this point I’d probably take a picture of the thermostat wiring.
- Remove the upper and lower thermostat wires.
- Pry the thermostats out. They just clip in.
- Install the new upper and lower thermostats using your picture as the wiring diagram.
- Using your electric water heater element wrench and a long phillips head screwdriver remove the upper and lower heating elements.
- Be sure that any old rubber seals around the old elements are removed as well.
- Wipe a small amount of thread compound on the threads of the heating elements and install them snugly.
- Refill the electric water heater completely. Confirm all air is out of the tank.
- Turn off the faucet on the upper floor when all air has stopped coming out of it.
- Reinstall all insulation and the upper and lower panels on the water heater.
- Turn the electrical breaker on. You should be able to put your hear on the tank shell near the upper element to hear the humming of your new electrical element heating.
- It will take about 45 minutes for the electric water heater to be hot again.
We hope this DIY water heater repair page has been helpful. And we also hope you’ll consider Advocate Master Plumbing for your next water heater repair.