Basement noises explained
Water Heater Making Noise in Minneapolis?
Most sounds from a basement heater in Minneapolis are harmless or easy to fix. A few are worth a call.
A water heater is not a quiet appliance. Burners light, water heats and expands, metal shifts and pipes carry water in and out. Some noise is normal.
The trick is telling the normal sounds from the ones that mean wear, a part failing or pressure that is too high. This guide goes through the common ones in roughly the order people call about them.
Quick answers
- Popping or rumbling usually means sediment on the bottom of the tank.
- Sizzling on a gas tank in winter is often condensation dripping onto the burner, and it fades as the tank heats.
- Ticking usually comes from pipes and heat traps expanding and contracting.
- Knocking when a faucet shuts is water hammer, a piping issue more than a heater issue.
- A screaming or whistling sound near a valve, or a relief valve hissing, needs a call.
Popping, rumbling and crackling
This sound tops the list of noise calls. Minerals from hard water settle on the bottom of the tank as sediment. Water gets trapped under that crust, turns to steam in small pockets when the burner fires, and pops as the bubbles escape.
On softened city water like Minneapolis or St. Paul, it builds slowly. On unsoftened suburban well water, it builds fast.
A flush usually quiets it. If a flush no longer helps, the sediment may be packed too hard, and the tank bottom is running hotter than it should. On an older tank, that is a sign the end is coming.
Electric tanks make a related sound, a hiss or crackle from scale baking onto the elements.
Sizzling on a gas tank in winter
A sizzle under the tank right after a lot of hot water use is very common in Minnesota winters. When the tank refills with near-freezing water, moisture from the burning gas condenses on the cold tank bottom and drips onto the burner. It sizzles until the tank warms up, then stops.
That is normal. It also explains small puddles under some gas tanks in winter that disappear later in the day.
If the sizzling goes on all the time, or the puddle keeps growing when the tank is hot, look for a real leak.
Ticking and tapping
Ticking usually comes from the pipes. Hot water expands copper and steel, and pipes tick as they slide against straps and joists. Many tanks also have heat trap nipples on top, small fittings that keep hot water from rising out of the tank, and some of those tick as water moves.
Ticking is a nuisance, not a danger. A plumber can swap noisy heat traps or add cushioned straps where pipes rub.
Humming, whining and buzzing
On an electric tank, a low hum while it heats often comes from an element vibrating in the water. A loose element can hum louder. It is usually harmless.
A heat pump water heater hums whenever its compressor and fan run. That is normal and sounds about like a dehumidifier.
Power vent tanks have a fan on top. A whine or rattle from that fan can mean a worn bearing or a loose part. It is worth having looked at before the fan fails and shuts the heater down.
Knocking and banging
A bang in the pipes when a faucet, washer or dishwasher valve shuts is water hammer. Fast closing valves stop moving water suddenly, and the shock travels through the pipes.
Water hammer is more of a piping problem than a heater problem, but it strains everything connected, including the tank. Arrestors near the fast closing valves fix it. If the house has high water pressure, a pressure reducing valve and an expansion tank may help too.
Sounds that need a call soon
- A hiss or steady drip at the relief valve. It may be opening because of high pressure or temperature. Do not cap it.
- A loud screech or whistle near a valve. Often a partly closed valve or a restriction.
- A burner that lights with a bang. Delayed ignition from a dirty burner or low gas pressure.
- Any sound along with a gas smell or soot. Leave the house and call the gas utility from outside.
Other warning signs, and what fixing them costs, are on the water heater repair in Minneapolis front page. If you book a visit, check the tech's license and insurance and agree on the price first.
Rumbling that comes with other signs
Most rumbling is sediment and nothing more. A few combinations deserve faster attention.
- Rumbling plus a relief valve that drips or discharges. The tank may be overheating or over-pressurizing.
- Rumbling plus water much hotter than usual at the tap. A control may be stuck on.
- Rumbling plus a tank that feels very hot on the outside jacket.
In any of those cases, shut off the gas or the power to the heater, stay away from the hot taps and call. Do not open the relief valve lever to test it while the tank is overheating.
When you call about any noise, a short phone recording of the sound helps the person on the other end narrow it down.
Reader questions on noises
Is a popping water heater dangerous?
Not right away. It means sediment is building up. Over time that wears the tank, so a flush is worth doing soon.
Why does my gas water heater sizzle only in winter?
Cold incoming water makes the tank bottom cold, and combustion moisture condenses and drips onto the burner. It stops when the tank warms.
Can I flush the tank to stop the noise?
Often yes. Turn off gas or power, close the cold supply and drain through the drain valve until it runs clear.
Why do my pipes bang when the washer stops filling?
That is water hammer from the washer's fast closing valve. A water hammer arrestor near the washer usually fixes it.