Gas
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Troubleshooting Gas Water Heaters

• All following troubleshooting information is based on conventional gas water heater design and does not include electronic ignition or flue devices.

• All possible causes and solutions are in random order. 

• A repair technician should be comfortable with correct repair methods.

• Many other possible causes may exist and you should track them for future reference.

• Please return to our Home Page for contact information if you wish to add to our list for your future reference.

• Review the Tricks of the Trade section for more helpful information.

• As of 2003, a new style gas water heater must be installed for certain residential installations. This flame arrestor style gas water heater is not listed below.

 

Problem	Possible Cause	Possible Solution	Notes
No gas flow to pilot	No gas from meter	Turned off at meter	Call gas provider
No gas flow to pilot	No gas from regulator	Debris in regulator	Remove and inspect
No gas flow to pilot	Faulty regulator	Replace regulator	Cannot rebuild unless you are certified
No gas flow to pilot	Crimped pilot tube	Repair or replace tube
No gas flow to pilot	Leak in pilot tube	Replace tube
No pilot flame	No gas flow from regulator	See above information
No pilot flame	Defective thermocouple	Replace thermocouple	Residential Type
No pilot flame	Defective thermopile	Replace thermopile	Commercial Type
No pilot flame	Air in gas piping	Purge air from piping
No pilot flame	Defective regulator	Replace regulator	Cannot rebuild unless you are certified
No gas flow to burner	Defective regulator	Replace regulator	Cannot rebuild unless you are certified
No gas flow to burner	Crimped burner tube	Repair or replace tube
No gas flow to burner	Blockage in burner tube	Remove and clean
No gas flow to burner	Water is too hot	Run water to cool tank	Push reset button Commercial Type
No gas flow to burner	Defective high limit device	Replace device	Commercial Type
Relief valve leaking	Water is too hot	Run water to cool tank	Lower thermostat setting
Relief valve leaking	Defective relief valve	Replace relief valve	Same rating
Relief valve leaking	Excessive pressure	Install expansion tank	Size per heater
Relief valve leaking	Excessive pressure	Check PRV to system	Maximum is 80 PSI (NC Code, Check Yours)
Low water temperature	Thermostat set too low	Adjust temperature
Low water temperature	Dip tube failure	Inspect and replace	Top fed type heater
Low water temperature	Defective thermostat	Replace thermostat
Slow recovery	Sediment in tank	Drain and flush tank	Residential type
Slow recovery	Dirty burner assembly	Clean burner
Slow recovery	Poor flame	Adjust burner air
Slow recovery	Poor flame	Need combustion air	Install air supply duct
Not enough hot water	Improper size heater	Calculate demand	Size per BTU required
Not enough hot water	See above information	See above information	Recovery / Temperature
Popping / banging noise	Calcium build up	Drain and flush tank	Noise while heating
Popping / banging noise	Sediment build up	Drain and flush tank	Noise while heating
Banging noise	Check valve slamming	Install shock absorber	Noise after water flow
Banging noise	Solenoid to equipment somewhere in system	Install shock absorber	At equipment location
Fume odor	Poor draft on flue system	Flue pipe installation	Check horizontal pipe
Fume odor	Poor draft on flue system	Termination location	Check roof area
Gas odor	Leak on piping system	Soap all piping joints	Repair Leaks
Soot build up	Poor draft on flue system	See above information	Fume odor
Soot build up	Poor draft on flue system	Install draft fan	May void warranty
Soot build up	Poor combustion air	Install air supply ducts	High and low air
Soot build up	Poor burner flame	Clean and adjust	See above information
Flame back flash	Negative air pressure	Isolate heater air	Equalize with outside air
Flame back flash	Restaurant draft hood	Isolate heater air	Check louver door

 

Have your troubleshooting items added to this chart
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