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Banging Pipes When Heat Starts

Banging pipes when heat kicks on usually means expanding metal ducts or water hammer in hydronic lines — not a furnace error code. Check vents and duct support; professional duct work runs $300–$1,000.

Reviewed July 2026

What does banging pipes when heat starts mean?

Sheet metal ducts pop when they expand from sudden heat. Hydronic systems can hammer when valves close quickly. These are mechanical noise issues, though pressure-related furnace codes may appear on systems with blocked condensate or vent issues.

What usually causes banging pipes when heat starts?

Expanding ductwork (oil-canning)most common

Typical repair: $20–$75

Closed dampers or ventscommon

Typical repair: $20–$75

Water hammer in hydronic heatingpossible

Typical repair: $175–$550

Find your exact error code

Select your furnace brand to jump to the code page for this symptom.

Carrier31Pressure-switch circuit did not closeBryant31Pressure-switch circuit did not closePayne31Pressure-switch circuit did not closeGoodmanE2Pressure-switch circuit did not close

What should I check first when banging pipes when heat starts?

  1. Open all vents and dampers.
  2. Listen for whether the bang is from ducts or pipes.
  3. Replace the air filter to reduce airflow surges.
  4. Ask an HVAC tech about duct bracing or hydronic air bleeding.

What a repair costs

A furnace filter replacement typically costs between $20 and $75 nationally.

Typical repair cost
$20 – $75furnace filter replacement
Where the money goes
Part $10–$50Labor $0–$65Typical labor time: 0.25 hrs

This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.