Water Heater Buzzing Noise: Find the Source
On this page (7 sections)
The Short Answer: A low hum from an electric tank while it heats usually comes from the elements, which vibrate when scaled or when water rushes past. Heat-pump models hum like a refrigerator while running. A buzz that grows louder, a grinding fan, or any buzzing at the electrical panel needs a closer look. Start by noting where the sound comes from and when.
Pin down the sound
| Where and when | Likely source | Concern level |
|---|---|---|
| Electric tank, only while heating | Element vibrating, often with scale build-up | Low; flushing may help |
| Electric tank, new loud buzz after an element replacement | Element not seated or tightened correctly | Have it checked |
| Top of a heat-pump water heater | Compressor and fan | Normal; see hybrid water heater noise |
| Gas control, a brief click or hum as the burner starts | Gas valve opening | Normal if short |
| Gas control, a buzz that lasts or keeps getting louder | Valve or its electronics wearing | Have it checked |
| Fan on a power-vent or tankless heater | Blower motor; louder with worn bearings | See exhaust blower noise |
| Electrical panel, at the heater’s breaker | Loose connection or failing breaker | Turn off; see breaker buzzing |
| Popping, rumbling, or crackling while heating | Sediment, not a buzz | See sounds like rocks |
Electric tanks: the element hum
Electric elements are long metal loops in the water. When scale builds up on them, or when water flows past during heavy use, they can vibrate and hum. A slight hum that has been there for years and only happens during heating is usually harmless. A tank that also pops and rumbles probably has sediment as well, and flushing according to the manufacturer’s instructions may quiet both.
Be more cautious if the hum is new and loud, or if it comes with tripped breakers, a burning smell, or lukewarm water. Those point to a damaged element or a loose connection. Those parts sit behind electrical covers, so a technician should test them with the power locked off.
Gas heaters: valve and fan sounds
Gas controls make a short click or hum when they open. Electronic controls and power-vent models also have fans and igniters that hum briefly at startup. A buzz that persists through the whole burn, or a fan that rattles or grinds, is worth reporting to a technician. If the buzz comes with a gas smell, a yellow flame, or a bang at ignition, turn the heater off and leave. See smell gas when water heater turns on.
Heat-pump water heaters
A steady refrigerator-like hum and the sound of moving air are normal while the heat pump runs. New rattles usually come from loose panels or the unit not sitting level. A grinding fan, a clanking compressor, or a loud hum with no heating needs service. If the unit sits in a small closet, sound carries more. Some manuals list the minimum room size and clearances.
What you can check safely
- Listen at the heater, at the gas control, and at the panel to find where the sound comes from.
- Note whether it happens only while heating, all the time, or only at startup.
- For electric tanks, note whether hot water and breaker behavior are normal.
- For heat-pump units, check that the unit is level and the access panels are secure.
- Don’t remove electrical covers or tighten elements yourself.
What the technician will check
A technician will test elements and their connections with the power isolated, check whether a replacement element was seated and tightened properly, and inspect for scale. On gas units, they listen to and test the gas control and the blower. On heat-pump units, they check the fan, compressor mounting, and panels. A panel buzz is a job for an electrician.
Frequently Asked Questions
Q: Will flushing the tank stop the buzzing? A: It can help if scale or sediment around the elements is part of the cause. It won’t fix a failing gas valve, fan, breaker, or a loose electrical connection.
Q: My A. O. Smith hums. Is there a brand-specific cause? A: The causes are mostly the same across brands, but see A. O. Smith water heater humming noise for model notes.
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.
- A. O. Smith: standard electric no-hot-water diagnostic chart (opens in a new tab)Professional diagnostic context for standard electric storage heaters; not instructions to open or test your appliance.
- 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