No Hot Water: DIY Guide to Repair a Water Heater


no hot water

There are not too many things worse than taking a hot shower and then running out of hot water. Realizing you have no hot water because your water heater is not working can send some people into a panic. However, this may be easier to fix than you may think. To help, we’ve put together this guide to help troubleshoot why your tank water heater is not producing hot water.

Water heaters that produce no hot water often have a power failure, no fuel source, or a part of the water heater has failed. Electric water heaters usually have a tripped breaker or failed heating element. Gas water heaters can have no fuel source, ignition failure to the pilot light, or a burner failure.

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Let’s examine some of the reasons why your water heater may not be heating or producing hot water and what you can do to get the hot water flowing again.

If you have a tankless water heater and are running out of hot water, see Why Tankless Water Heaters Run Out of Hot Water.

If your water heater has a water heater blanket installed, you’ll need to remove it to troubleshoot the steps below.

Troubleshoot Why Your Electric Water Heater Is Not Working or Heating

Check the Power Supply

We need to check the circuit breaker inside the panel box to see if it has tripped. To do this, check your water heater breaker located inside your electrical panel box to see if it’s in the neutral or middle position. 

  1. If the breaker has not tripped, you can move on to the next section.
  2. If the breaker is tripped, push it to the OFF position and then into the ON position.
    • If the breaker immediately trips back, you likely have a faulty breaker or an electrical short somewhere in the circuit between the panel box and the water heater. If this happens, you need to immediately contact a licensed electrician to examine and repair the circuit.
    • If the breaker stays ON when reset, the problem most likely lies at the water heater itself and not in the electrical circuit. Let’s move on and look at some of the things that could be wrong with the water heater.
  3. Wait 30 minutes to see if the water heater recovers and begins producing hot water.

If your breaker has tripped and will not reset. there are three likely scenarios. Let’s look at these below:

  • Burnt heating elements – When heating elements fail, they will often split. When this happens, the element will short out. This exposes the electrical components to water, which will trip your breaker and prevent it from resetting.
  • The breaker or wiring – Breakers have a limited lifespan and can fail. A worn-out or weak breaker will trip when the water heater fires up and draws power. The wiring from the panel to the water heater can become loose, causing the breaker to trip.
  • Your thermostat – If your water heater’s thermostat fails, it can draw more electricity than the circuit can handle. This will cause the breaker to trip.

Check the high-temperature limit switch

Now let’s check the water heater’s high-temperature limit switch (aka reset button). This switch is found behind the upper element access panel located on the water heater’s top side. This reset will trip to shut off power to the water heater when the temperature inside the water heater exceeds 180 degrees Fahrenheit.

  1. Turn OFF the power to the water heater.
  2. Remove the upper element access panel cover.
  3. Pull back the insulation to expose the thermostat.
  4. Above the upper heating element, you will see a large red button.
  5. Check to see if this button has tripped.
  6. Reset the button if needed.  
  7. Turn the breaker back ON.

Insider’s Tip: If the reset button has tripped, this indicates that a problem exists. The thermostat normally cycles on and off once the tank has recovered and achieved the desired temperature. If the thermostat does not turn off and continues to heat, the reset button will trip. You should check to see if your thermostat is faulty. If you are unsure how to do this, you should immediately have your water heater serviced by a licensed plumber.

Water heater service disconnect

Some water heaters have a service disconnect box at the water heater. Modern building codes require a service disconnect to be installed within the eyesight of the water heater. This is not needed if the electrical panel box is within eyesight of the water heater. If you have a service disconnect:

  1. Check to verify if the service disconnect is turned ON. This can be in the form of a pull-style disconnect or a breaker.
    • For pull-style disconnects, remove the disconnect and reinsert it to be sure it’s making a snug and secure connection.
    • For breaker style disconnects, check to see if the breaker has tripped. If so, turn the breaker OFF and then back to the ON position.
  2. Wait 30 minutes to see if the water heater begins working.

Check the wiring connections

WARNING: Working with electricity is very dangerous and can kill you. Be sure the power is OFF before doing any work with wiring and electrical connections.

Next, we need to check the wiring connections located at the water heater. To do this, we need to:

  • Turn the breaker OFF to the water heater. Use a voltage pen to check to be sure the power is off.
  • Remove the junction box cover at the top of the water heater.
  • Check the wire connections to be sure the wires are snug and secure.
  • Check the ground wire to be sure it is snug and secure.

Check Your Thermostat & Heating Elements

Each of the heating elements in a water heater requires a thermostat. In a single element water heater, there is only one thermostat. In more modern dual-element systems, there are two thermostats, one controlling each heating element. You’ll need a multimeter to check to determine if the thermostat has failed.

The most common reason why a water heater is not producing hot water is a failed heating element. Most water heaters are a dual element system meaning they have two heating elements; an upper element and a lower element. 

The upper heating element also controls the lower heating element. If the lower heating element has failed, the upper heating element may still function; however, neither element will function if the upper heating element has failed.

If the lower heating element has failed, and the upper heating element is still working, the water heater will only produce about half the hot water capacity. Your hot water will run out quickly or, at best, is only lukewarm. 

If the upper heating element fails, no hot water will be produced at all regardless of whether the lower heating element is working or not.

Troubleshoot Why Your Gas Water Heater Is Not Working or Heating

Let’s look at some of the reasons why your gas water heater is not producing any hot water. 

Check the gas supply

Gas water heaters are powered by either natural gas (municipal supply) or propane gas (provided by an onsite tank). The first thing we need to do is check the gas supply coming into the property.

If there is natural gas in the house, check the meter to verify the gas has not been turned off. If the gas has been turned off for non-payment of the bill, the valve will be perpendicular with a pin lock in the meter.

For propane tanks, check the tank to verify there is propane in the tank. Most tanks have a gauge on the top that indicates how much propane is in the tank. After you confirm there is propane gas in the tank, check the shutoff valve to be sure it is open.

Next, there should be a shutoff valve located on the gas line within the eyesight of the water heater. The shutoff valve should be in line with the supply pipe. If the valve is perpendicular or at a 90° angle to the supply pipe, the gas is turned off. If the gas valve is off, turn the valve back inline to turn the gas on to the water heater. You’ll need to re-light the pilot light. We will go over this shortly.

Check the pilot light

Gas water heaters are not overly difficult to work on. However, if you are unsure how to dismantle and reassemble these components, you should contact a licensed plumber for service or repair. 

If the gas is on, we need to check to see if the pilot light is on. Remove the bottom cover and look through the sight glass to see if the pilot is lit.

If the pilot light is off you should first try to relight it. To light the pilot:

  • On the control valve, turn the knob to the Pilot position and press and hold.
  • With the knob pressed, push the igniter to light the pilot light.
  • Once the pilot is lit, hold the knob in for up to 60 seconds to allow any air to escape and the flame to hold.
  • Once the pilot is lit, turn the knob on the control valve back to the On position and adjust the temperature setting on the control valve to your desired temperature.

If the pilot does not light or stay lit, there are several items that we need to check. You need to check the following items: 

  • Check the thermopile or thermocouple – inspect the thermocouple to be sure it is connected tightly to the gas line. This should be positioned so that the tip is in the pilot flame. There could also be a clog in the thermocouple, or it may need replacement. Check this with a voltmeter; if the test fails, replace the thermopile assembly.
  • Check the thermal switch to see if the reset has tripped. The thermal switch is located on the bottom of the water heater. Press the reset on the center of the switch as indicated in the video. The thermal switch is an important safety device, and if the thermal switch has failed, it needs replacement.
  • Check the control valve – if the thermopile test passes, you’ll likely need to replace the control valve. Check the status lights on the front of the control valve assembly. Error codes 4, 5, & 7 will require the control valve assembly to be replaced.
    • Status Light Codes Normal Flashes:
      • 0 Flashes Indicate Control Off/Pilot Out.
      • 1 Flash Indicates Normal Operation.
      • A solid continuous light indicates that the gas control valve/thermostat is shutting down.
      • Diagnostic Flashes: If the water heater is not working, look for the following diagnostic flashes after lighting the pilot.
        • 2 Flashes Indicate Thermopile Voltage Low
        • 4 Flashes Indicates Overheat Failure
        • 5 Flashes Indicates Sensor Failure
        • 7 Flashes Indicate Electronic Control Failure
        • 8 Flashes See “Status Light and Diagnostic Code Troubleshooting Chart.”
  • There may be air in the gas line – If the pilot light goes out or the gas flow is interrupted, air will likely collect and the gas line. The air in the gas line would prohibit the pilot from lighting or staying lit. Pump the pilot knob several times to force air out the line. While holding the pilot knob in, push the igniter to light the pilot. You may need to repeat this process several times. 
  • Damage gas supply line – check the gas supply piping for damage or bends which could restrict gas flow. If a gas leak is present, there likely won’t be enough fuel to keep the pilot lit.
  • Dirty burner – burners can sometimes build up soot that can prohibit the burner from functioning properly. If the burner is dirty, it can be removed and cleaned.
  • Poor ventilation – gas water heaters require proper ventilation. Check the air intakes around the bottom of the water heater to ensure they are clean and not obstructed. Vent pipes can become misaligned, blocked, or damaged. If ventilation is restricted, the water heater will not function properly. Check your vent pipes to be sure they are not blocked.

If the Water is not Hot Enough

As water heaters age, parts began to wear out, reducing the output of hot water. If you find that the water heater is functioning properly but just isn’t producing enough hot water, here are some things that you can check.

Check the Thermostat Settings

Check to be sure that the thermostat is set properly. Since the control valve assembly on gas water heaters is outside the unit, check to be sure the knob has not been turned to a lower setting. Take a temperature reading of the hot water output and compare it against the temperature setting.

Inspect the Burners

As mentioned earlier, dirty burners on gas water heaters can reduce hot water output as the flame doesn’t burn hot enough. Cleaning and servicing the water heater can get hot water flowing again. 

Examine the Dip Tube

The dip tube is responsible for supplying cold water to the bottom of the water heater for optimal performance. Some older water heaters manufactured between 1993-1996 had faulty dip tubes that would fail by breaking off inside the water heater.

If you suspect the dip tube could be bad, the only way to confirm is to remove it and see. Inspect the dip tube to see if it is intact and in good condition. If the dip tube is broken off inside the water heater, you’ll need to replace the water heater because there’s no way to retrieve the broken dip tube from inside the tank.

Failed Lower Heating Element

We touched on this earlier in the article as well, but it’s worth mentioning again. If the lower heating element in an electric water heater fails, the upper heating element will heat the water in the water heater’s top half. Still, the lower heating element will not heat the water in the lower half of the tank. As this hot water in the top mixes with colder water in the bottom, the result is a lukewarm output.

You can know if the lower element has failed by testing it with a voltmeter for continuity. Another way is that the hot water temperature output will run out quickly or be less than the desired thermostat setting.

A Leak in the Water Heater Tank

Finally, inspect the water heater for water leaks. Leaks coming from the bottom of the water heater resulting in a constant cold water supply entering the water heater. Due to the leak, the cold water entering the tank has no opportunity to heat up. 

Check out our article on How to Repair a Leaking Water Heater – Complete Step by Step Guide for complete information on diagnosing and repairing a leak in your water heater.

Conclusion

Most repairs to water heaters are relatively easy to do. However, others can be more complex and are better left to licensed plumbers.

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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