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Commonly Reported HVAC Problems:

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Assorted Water Heater Problems:

(For Gas and Electric Water Heaters)

Please do not attempt to repair your own hot water heater unless you are qualified.

The information below, for assorted water heater problems, assumes that the water heater has been properly installed and was operating correctly before any problems developed. These are just general guidelines, covering the most common water heating problems, thus helping to make you a more educated consumer.

  1. Problem: No Hot Water - Gas Water Heater
  2. Problem: No Hot Water - Electric Water Heater
  3. Problem: Insufficient Hot Water
  4. Problem: Slow Hot Water Recovery
  5. Problem: Discharge From TP/Relief Valve
  6. Problem: Pilot Light Won't Stay Lit
  7. Problem: Popping or Banging Noise
  8. Problem: Hot Water Smells Really Bad!
  9. Problem: Leaking Tank


Assorted Problems...

1. No Hot Water - Gas Water Heater - Remove the inner and outer burner access covers and check to see if the pilot light is lit.

* Caution: Most modern water heaters no longer use standing pilots. They use electronic ignition to ignite the gas. Do not attempt to manually light an electronic ignition system.

If the pilot light is not lit:

  • Attempt to re-light the pilot light, following the instructions posted on your water heater. Or click here for instructions.
  • If the pilot light will not re-light, the problem could be a clogged pilot line or orifice, or gas is not reaching the water heater. Call for service.
  • If the pilot light will light but does not stay lit when the gas valve control is released, the problem could be a defective or loose thermocouple, or perhaps a faulty gas control valve. Make sure the thermocouple connection to the control valve is tight.

If the pilot light is lit:

  • Turn on a hot water tap and let the water run for several minutes. Check to see if the burner comes on. If not, run the hot water several more minutes. If the burner still does not come on, the problem could be a defective control valve/thermostat.
  • Check to see if the control valve knob is in the "on" setting and not set to the "pilot" position.

2. No Hot Water - Electric Water Heater - If you have no hot water from an electric Hot Water Heater, first make sure the breakers are on. Otherwise, it is most likely either a bad upper element or thermostat, or it is off on a high limit safety. Some water heaters have a resetable safety switch at the upper thermostat. This usually requires removing the upper access panel.

electric hot water heater breaker

* Caution: High Voltage connections are behind access doors. Turn off all power to the appliance at the main panel box before removing the water heater panel. Use caution when removing the panel and double-check electrical connections with a volt meter. If you are unsure how, then you shouldn't be attempting this!

Once confirmed that the electric is off, check to see if the red reset button has popped out. If so try resetting it, you will hear a click. Then re-install the panel cover and reset the breaker. You should hear the unit start to charge. Keep in mind, that if the upper limit opens, it is usually because a thermostat stuck closed and it will do so again, requiring changing.

3. Insufficient Hot Water - Check the thermostat setting, it may be set too low. Check for leaking faucets. There could be a dip tube problem. If the dip tube has broken or fallen off, incoming cold water will be drawn out through the hot water outlet without being heated. Keep in mind you really shouldn't try checking this yourself!

Other possible causes include clogged burners and low gas pressure, which would also require a service call.

4. Slow Hot Water Recovery - Sediment buildup on the bottom of the water heater can do this. Flushing the water heater may help. Other possible causes may be insufficient combustion air; caused by insufficient ventilation, or improper burner operation.

If you are running out of hot water with this type of system, it's possible that the thermostat is set too low or it's faulty. There could also be a bad circulator or circulator relay, or the zone could be air-bound - requiring purging.

5. Discharge From TP/Relief Valve - The relief valve will open if either the water temperature is too high, or if the pressure gets too high. If the inlet to the water heater is fed directly from the water main, with no pressure relief valves or check valves between them, then when the water is heated and expands, the extra volume of water simply flows back toward the water main.

relief valve leaking on floor

If however, there is a blockage such as a check valve or pressure reducing valve with a defective bypass, then the increase in water volume has nowhere to go, and the pressure will increase dramatically.

Placing an expansion tank in the line, at the inlet, will give the increased volume of water someplace to go and prevent the relief valve from opening.

Another possibility is that the City water pressure has increased above the setting of the relief valve. Again, the installation of an expansion tank can help solve this problem, at least with a minor to moderate increase in city pressure. A significant pressure increase will still however, cause the relief valve to open.

6. Pilot Light Won't Stay Lit - (Standing pilot models only) Sometimes a draft will blow the pilot light out. Make sure the burner access covers are in place. Other possible causes include dirt in the gas line, loose thermocouple connections, or a defective thermocouple. For more on this problem, click here.

7. Popping or Banging Noise - Scale can build up in the bottom of the tank; causing all sorts of noises to occur while the water heater is heating water. Try flushing the tank.

8. Hot Water Smells Really Bad! - Certain types of bacteria can react with the magnesium anode rod resulting in a rotten egg odor. Cleaning the tank using chlorine bleach, or changing the anode rod to aluminum usually solves the problem.

9. Leaking Tank - All tanks eventually leak! It's unavoidable, like death and taxes! No fix for this, sorry! Replace the water heater.

hot water heater leaking

Please keep in mind that the information found on our website is provided free of charge and Hannabery HVAC does not assume any liability resulting from the information we provide. We hope this information helps, but please note that these are just rough guidelines, and not all possible situations are covered. Your HVAC system should be inspected and repaired by a trained technician.

Commonly Reported HVAC Problems

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