John Wood Water Hammer / Combustion or Vent Vibration

John Wood water heater vibrates excessively or makes banging noises in the vent or piping

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Sudden valve closures causing water hammer, Loose vent piping, Improperly supported water lines, Delayed ignition causing small explosions

How to Fix / Troubleshooting

Safety: Turn off gas if you suspect delayed ignition (loud bangs at burner start).

  • 1. Water hammer arrestors: Install water hammer arrestors near quick-closing valves (dishwasher, washing machine) to reduce banging in pipes.
  • 2. Secure piping: Add pipe clamps or supports to loose hot and cold water lines and vent pipes.
  • 3. Delayed ignition: If bangs occur at burner start, have a technician clean the burner and check gas pressure and ignition timing.
  • 4. Vent vibration: Ensure vent sections are properly joined and supported per John Wood installation instructions.
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Repair Difficulty

Medium 3/5

Required Part

Water Piping and Vent Piping
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