Gas Hot Water System

continuous-flow-rinnai-gasTroubleshooting Gas Water Heaters

Knowing how to light the pilot is one key to living with a gas water heater; see the instructions on the tank. For safety, a gas heater has a thermocouple. This is thermoelectric device that impinges on the pilot flame and shuts off the gas if the pilot light goes out. The gas flame should be blue. If it’s orange, adjust the shutter; if it’s still orange, call for service.

Twice a year, inspect the flue assembly to be sure it’s properly aligned and all its joints are sealed. Then check the flue by placing your hand near the draft diverter (with the burner on); air flowing out indicates an obstruction that should be removed. Every year or two, shut off the gas, remove the access panel, and clean the burner ports, using stiff wire or a needle. If you ever smell gas, get out of the house immediately and call the gas company.

*Note premature failure on water heaters (and plumbing fixtures) is most often attributed to excessive water pressure (above 80 p.s.i.). Your plumber can test your water pressure to see if it is within safe limits, and make suggestions to reduce pressure if necessary.

There is no hot water.

Check for:

  • Unlit pilot light.
  • Pilot light won’t keep burning.
  • Clogged burner
  • Defective thermocouple.
  • The gas is not coming out.


  • Carefully relight the pilot.
  • Make sure the gas controls are completely turned on. Then check the thermocouple and be sure it is firmly connected to the gas control unit and positioned near the pilot flame.
  • Call a qualified plumber.
  • Replace the thermocouple.
  • Inspect or test gas control valve

There isn’t enough hot water.

  • Check for:
  • Incorrectly set thermostat.
  • Defective thermostat.
  • Too small of a water tank
  • Clogged burner.
  • Sediment has formed in the tank.
  • Leaking hot water faucets.


  • Turn the thermostat higher.
  • Call a qualified plumbing contractor.
  • Install a larger water tank.
  • Turn off the gas and drain the tank.
  • Repair or replace the faucets.

The water heater is very noisy.

Check for:

  • Scale and sediments in the tank.


  • Turn off the gas and drain the tank.

The water is too hot.

Check for:

  • Wrong setting on thermostat.
  • Defective thermostat.
  • Blocked exhaust vent.


  • Reset the thermostat.
  • Call a qualified plumbing contractor.
  • Check the vent and clear it.

Water is leaking from the heater.

Check for:

  • Leak in the draincock.
  • Leaking safety valve.
  • Hole in the tank.
  • Leak in the plumbing connection.


  • Close it tightly or replace it.
  • Check the water temperature. If it’s too hot, the thermostat may be broken. If the safety valve is defective, replace it.
  • Buy a new water heater.
  • Call a plumber.
  • Note premature wear & tear on water heaters (and plumbing fixtures) is most often attributed to excessive water pressure (above 80 p.s.i.). See information related to pressure reducing valves.