Pops and ticks are usually the ducts
Metal ducts grow a little when warm air runs through them and shrink again when they cool. That movement makes popping, ticking and light banging, mostly in the first few minutes after the heat comes on and again after it shuts off. It can be louder on the first cold nights of the season and in ducts that run through an attic or crawlspace.
If the sound happens at the start and end of a cycle and the house is heating fine, it is most likely just the ducts.
Keep a quick note on your phone for a day or two. Write down when the sound happens: right at startup, during the cycle or at shutdown. That one detail tells me more than anything else if you do call.
Check the easy things first
A dirty filter or a lot of closed registers raises the pressure in the ducts and makes the popping worse. Pull your filter and hold it up to a light. If you cannot see through it, replace it. Then walk the house and make sure supply vents and return grilles are open and not covered by furniture or rugs.
Sounds that mean turn it off
Some noises are not normal. If you hear any of these, turn the system off at the thermostat and call:
- Grinding or scraping from the furnace or blower
- A high squeal that does not go away
- A loud boom when the burners light
- A burning smell that keeps going past the first few minutes of the season
If you ever smell gas, do not touch the thermostat or any switches. Leave the house and call your gas company from outside. For any of the other sounds, call me at (470) 999-7395 or book a $79 diagnostic online.
