Video · Water Heaters
Water Heater Knocking Ends Here: Old Tank Out, Tankless In
Water heater knocking or popping usually means sediment on the tank bottom, with water trapped under it boiling as the burner fires. This old tank knocked its last, and a tankless took its place.
Job footageSwiftPro
- Topic
- Water Heaters
- Length
- 0:12
- Posted
- August 2, 2026
- Shot by
- The SwiftPro crew, Northern Virginia
What you’re seeing in this video
Snow lines the townhouse street as two techs, one pushing and one pulling, wheel an old tank water heater on a hand truck past a SwiftPro-wrapped truck. Cartoon meme clips pop in between shots for laughs.
The replacement is a wall-hung tankless water heater, with white PVC venting going out and copper piping coming in. With no tank, there's no sediment bed on a tank floor for water to boil under, so that particular noise is gone.
Why it matters in your house
- Early knocking can sometimes be quieted with a thorough flush. Once it's loud every time the burner fires, the sediment has usually hardened and the tank is losing efficiency.
- Knocking in the pipes right when a faucet shuts off is a different problem, called water hammer. That's a pressure issue, not the water heater.
- A noisy tank past 10 years is telling you the end is near. Replacing on your schedule beats a cold shower on a snowy morning.
Why is my water heater making a knocking noise?
Most often it's sediment. Minerals settle on the tank bottom, water gets trapped underneath, and when the burner heats it, it flashes into steam bubbles that pop and knock. A flush can help if it's caught early. If the noise is in the pipes when you shut a faucet, that's water hammer, and an arrestor or a pressure fix solves it.
Want it done at your place? See Water Heaters at SwiftPro or call (703) 997-9757.
More videos from the SwiftPro crew
0:46How Long Does It Take to Replace a Water Heater With a Tankless?
0:36Water Heater Replacement Process, Heard Up Close
0:38How Does a Water Heater Work? Two Techs Cut One Open to Show You
0:38How Long Do Water Heaters Last, and When It's Time for New
0:35Rusty Water Heater, Outside and In: Tyler Griffin Shows Both
1:05Power Vent Water Heater Install: Four Details Worth Seeing