**Your explanation is plausible: sheet-metal ducts expand as they warm and contract as they cool.** If a duct rubs against framing, that movement can produce a sharp ping. Another cause is a flat duct panel flexing as air pressure changes, called “oil-canning.” Some expansion noise is common; its loudness depends on how the ducts are fitted and supported. [Heating expert Richard Trethewey explains both causes here.](https://www.thisoldhouse.com/heating-cooling/how-to-quiet-noisy-ducts)

Start with a few simple checks:

- **Note when it happens.** Pings during warming and cooling suggest thermal movement. A pop exactly when the blower starts or stops suggests pressure-related flexing. These are clues to guide an inspection.
- **Check the furnace filter** and replace it if dirty, using the type specified for your system. Keep return grilles clear of furniture.
- **Open any supply registers you’ve deliberately closed.** Closing registers to quiet a room can create airflow and pressure problems. [Carrier explains that restriction here.](https://www.carrier.com/us/en/residential/hvac-resources/hvac-dampers/)
- **Listen near accessible ductwork through a heating cycle.** Look for a duct touching a joist or a broad panel visibly snapping inward or outward. Record the sound and timing to help a technician reproduce it. [Restore’s diagnostic guidance](https://www.restoreheatingcooling.com/blog/ductwork-popping-banging-temperature-change) recommends these observations.

**Yes, you can hire someone for a targeted repair.** Ask an HVAC contractor who does sheet-metal ductwork for a “duct popping/noise diagnosis.” Ask them to reproduce the noise, locate the moving section, and check static pressure if it coincides with blower operation.

Depending on the cause, a local fix might involve adjusting a support, adding suitable isolation pads where the duct contacts wood, or reinforcing a panel that flexes. These are repairs worth investigating before considering extensive replacement. [Trethewey recommends isolating contact points](https://www.thisoldhouse.com/heating-cooling/how-to-quiet-noisy-ducts); [Restore describes support, reinforcement, and airflow checks](https://www.restoreheatingcooling.com/blog/ductwork-popping-banging-temperature-change).

I’d start with the filter/register checks and locating the sound. Leave blower-speed changes and duct reshaping to the technician, since the repair needs to preserve the furnace’s required airflow.