Don't Purge a Water Heater Gas Line Yourself
On this page (4 sections)
The Short Answer: Do not open a water-heater gas fitting to release air. If ignition failed after gas work, leave the appliance off and contact the installer or gas utility. Air in a line is only one possible explanation. If you smell gas, leave immediately and call emergency services or the utility from outside, without operating switches or the appliance.
A Failed Start Does Not Prove There Is Air in the Line
After an installation or gas-service interruption, the heater may fail to start because of its supply, ignition sequence, venting, controls, or an installation defect. A delayed ignition or burner bang is a reason to stop, not a reason to keep trying until the line clears.
Record the work that was done, when service was restored, the model number, and any code already displayed. Do not repeat an ignition attempt to gather more evidence.
What You Can Do Safely
| Situation | Next step |
|---|---|
| Gas odor, hissing, or suspected leak | Leave and call for emergency assistance from a safe location |
| New heater never operated correctly | Contact the installer and leave the heater off |
| Gas service was interrupted | Ask the utility who must inspect and restore appliance operation |
| Loud or delayed ignition | Stop using the heater and arrange qualified service |
| Error code without odor | Photograph it only from a safe location and match the full model manual |
The PG&E gas-safety guidance (opens in a new tab) explains evacuation and avoiding ignition sources during a suspected leak. If gas was shut off at the meter, do not restore it yourself; follow your utility’s procedure.
What the Professional Needs to Establish
The installer or qualified gas technician needs to verify the applicable commissioning procedure, fuel supply, leak tightness, and safe ignition. Purging methods and requirements depend on the installation and applicable rules. This guide intentionally does not give a gas-release procedure, pressure setting, or fitting-opening sequence.
Do not loosen a union, connector, test plug, or burner fitting. Do not try to prove a leak with a flame or search for it inside a building that smells of gas. Owning a manometer does not establish competence to commission an appliance.
Frequently Asked Questions
Q: Can I bleed the line by holding down the pilot control? A: Do not use the appliance controls as an improvised purge procedure. After a failed start following gas work, contact the installer and use only the applicable manufacturer instructions.
Q: Does a bang on ignition mean air is the problem? A: Not necessarily. Several combustion or ignition faults can cause delayed ignition. Stop using the heater and have it assessed.
Q: Who should I contact first if I smell gas? A: Leave first. From a safe location, call emergency services or your gas utility using the emergency number for your area.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- PG&E: recognizing and responding to a gas leak (opens in a new tab)Emergency actions for suspected fuel-gas leaks.
Editorial standards and corrections · Prepare a useful service request