Quick Answer:
A ticking noise after installing an expansion tank most often comes from metal and pipe supports heating and cooling, or from the tank and its fittings moving slightly as water temperature changes. Run a hot tap, stop it, and listen during cooling to confirm the behavior. If the sound is coming through finished walls or ceilings, have a plumber check pipe supports and routing before you open cavities.
Why This Happens
When hot water flows, pipes and nearby metal parts expand. When the water cools the parts contract. That change in size can make small contacts slip, scrape or tap against framing, hangers, brackets or drywall. An expansion tank adds new fittings and sometimes a new hanger or bracket, so a previously quiet system can start to click as parts settle.
If the sound seems like water striking a surface or small drops, compare notes with Clicking that sounds like dripping. If the pattern only shows up at certain hours, it may match issues described in Clicking only at night.
Step-by-Step What to Do
1. Reproduce the noise
- Open a hot-water faucet and let it run for a minute to warm the piping around the tank.
- Shut the faucet off and listen carefully for the ticking as the system cools—the noise often appears during the cooling phase.
2. Feel for movement
- Press lightly on the wall or ceiling near where you hear the sound to feel for vibration or movement. Small shifts are normal with thermal expansion; large movement suggests a loose support.
3. Note how the sound behaves
- Listen to see whether the ticking fades gradually as the system cools or whether it stays sharp and intermittent. Gradual fade usually indicates thermal contraction; sudden sharp ticks can mean parts are catching on something.
4. Inspect visible connections and supports
- With the water off to the tank if possible, look at visible hangers, straps and fittings for obvious looseness or metal-on-metal contact. Don’t force anything; a visual check may reveal a loose bracket.
5. If you can’t find the source, narrow the area
- Try to localize the sound by listening at different spots and repeating the hot-water run test. Mark the area where the noise is loudest and avoid opening finished surfaces until a professional confirms it’s safe.
What Not to Do
- Don’t wedge rigid shims or spray foam blindly into cavities. That can trap the pipe in a way that causes more stress or hides a developing leak.
- If ticking is near electrical runs or finished ceilings, have a plumber trace the pipe path first rather than poking or drilling into the space.
- Don’t hammer on pipes or over-tighten supports; that can damage fittings or cause misalignment.
When to Call a Professional
- Call a plumber if the ticking spreads through finished walls or ceilings and you can’t localize it; a pro can trace the piping, confirm safe support points, and access the area without damaging finishes.
- Also call if you notice leaks, banging that sounds like water hammer, persistent sharp noises, or if the ticking is close to electrical wiring—those situations need a trained eye.
Safety Notes
- Turn off water to the tank and relieve pressure before attempting any work on the piping.
- Avoid probing cavities where wiring may run; cutting into a finished ceiling or wall without knowing what’s behind it risks hitting electrical cables.
- If you find a leak or smell burning near the noise, shut off the main water and power and call a professional immediately.
Common Homeowner Questions
- Why does it only tick after the hot water is used?
Because the metal heats, expands, then contracts as it cools—most ticking happens during cooling. - Can I fix this myself?
Simple checks and visual tightening of visible hardware are okay, but avoid opening finished surfaces; call a plumber if the source isn’t obvious. - Is the ticking dangerous?
Usually not, but persistent sharp noises, leaks, or sounds near electrical runs should be inspected by a professional.
For more related articles, see the Ticking or Clicking Sounds During Water Use hub.