The short answer
Most noises in a Northern Virginia house are harmless: ticking pipes, a thump when the ducts warm up, a whoosh from a heat pump in defrost. The ones to act on are a boom when the furnace lights, a hiss with a gas smell, grinding from any motor, and a toilet that runs when nobody touched it. Here’s the sound, what it usually is and what we’d do.
Stop and act on these
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| The sound | What it usually is | What to do |
|---|---|---|
| A boom when the furnace lights | Gas builds up before it catches, called delayed ignition | Turn it off and call. |
| A hiss with a gas smell | A gas leak | Everyone out. Call your gas company and 911 from outside. |
| A CO alarm chirping or sounding | Check it: a pattern for a dead battery or end of life, or a real alarm | If it’s sounding, everyone out and call 911. |
| Grinding or screeching | A failing motor or bearing | Turn it off before it takes more parts. |
| Water running with every tap closed | A leak or a running toilet | Check the toilets, then the meter. |
| Sizzling at the water heater | Water dripping on a hot burner | Look for the drip, and call if it’s the tank. |
Gas first: here is what to do around a gas line. A carbon monoxide alarm gets this list, and if a tech says the boom came from a cracked heat exchanger, ask to see it.
The $67 Heating Check
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Pipes
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| The sound | What it usually is | What to do |
|---|---|---|
| Bang when a faucet or washer shuts off | Water hammer | Check pressure. An arrestor at that fixture fixes the rest. |
| Ticking after hot water runs | Hot pipes growing and shrinking | Usually nothing. |
| Whistling when someone flushes | A worn fill valve, or a partly closed shutoff | A cheap part. You may be able to do it. |
| Toilet refills by itself at 2 am | A leaky flapper | A cheap part, and it’s on our do-it-yourself list. |
| Hum or vibration when the water’s on | High pressure or a loose pipe | Check pressure first. |
| Gurgling drains | A blocked vent or a slow main | If two drains do it together, stop using water. |
A pressure gauge from a hardware store screws onto a hose spigot and tells you in a minute. Most plumbing codes cap house pressure at 80 psi. Here’s what the expansion tank is doing too, since a dead one shows up as pressure trouble. For the running toilet, here is the fix, and the rest of what you can fix yourself. Gurgling points at whether it is one fixture or the main line, and it’s the main that needs attention soon.
Water heater
Popping or rumbling is sediment on the bottom of the tank, and hard water makes it faster. Northern Virginia water is hard, so we hear it plenty. A flush helps if the tank isn’t too far gone. Here is how to maintain one, and what not to do to it. A loud tank past its usual life is worth planning around. If there’s water on the floor, go straight to this one.
Furnace and ducts
A soft click, then a whoosh of gas lighting, then the blower a minute later: normal. A thump in the walls when the ducts warm up: normal, and annoying. Rattling: a loose panel or something in the duct. A squeal: usually the blower motor. Our furnace noise guide goes through each one. If it starts and stops every few minutes, that’s short cycling, and it’s hard on the parts.
Heat pump outside
A whoosh and a fan that stops for a few minutes is defrost. A little steam goes with it. Here is what not to do when you see it. Rattling metal can be a loose panel or ice hitting the fan, so turn it off and look. Buzzing with no fan running deserves a call, since that’s often a capacitor and the motor can burn up trying.
Sump pump
Running a lot after rain is normal. Running every minute in dry weather isn’t, and neither is silence during a storm. Pour a bucket in the pit before you trust it.
Questions people ask
Why do my pipes bang when I turn off the faucet?
That’s water hammer. Moving water stops all at once and the pipe takes the shock. High water pressure makes it worse, so check that first. A plumber can add an arrestor near the fixture.
Why is my water heater popping?
Sediment on the bottom of the tank. Water trapped under it boils and pops through. A flush can quiet it if the tank isn’t too far gone.
Why do my pipes tick at night?
Hot water pipes grow a little as they warm and shrink as they cool, and they rub on whatever holds them. It’s usually harmless, and you’ll notice it most when the house is quiet.
Is a hissing sound near the furnace dangerous?
If you smell gas with it, yes. Get everyone outside and call your gas company and 911 from outside. If you don’t smell gas, it may just be air at a duct or a water valve, but it’s worth a call.
Book it
Tank popping, or pipes you can’t explain? Have someone listen with you there. The $99 water heater flush includes a walk through the house’s plumbing with photos. Book it from goswiftpro.com/cookiesoffer and free MOLTN cookies come with the visit. Or call (703) 997-9757. SwiftPro is rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
