Answer first, context after
My heater smells like rotten eggs. What do I do?
Treat it as a gas leak until proven otherwise. Natural gas and propane have no smell of their own, so utilities add a rotten egg odorant specifically so you can detect a leak. Get everyone out of the house first, do not flip switches or use the phone inside, and call 911 and your gas or propane supplier from outside. A repair conversation comes after everyone is safe, not before.
If you smell gas right now, leave the house and call 911 and your gas or propane supplier from outside. Do not text us first.
This is the one heating smell that gets its own page, because the right first move is not a phone call to us.
Why rotten eggs means gas. Natural gas and propane are odorless as they come. Suppliers add an odorant, mercaptan, whose entire job is to smell so unmistakably bad that people notice a leak long before it becomes dangerous. So a sulfur or rotten egg smell around a furnace, water heater, or stove is the safety system working exactly as designed.
Do this, in this order:
- Get everyone outside, including pets. Do not stop to investigate.
- Do not touch switches, thermostats, garage door openers, or phones inside the house. A small spark is the risk you are avoiding.
- Leave a door open as you go if that is easy, and do not light anything.
- From outside, call 911 and your gas or propane supplier. Both respond to this and neither will be annoyed that you called.
- Do not go back in until the fire department or the utility says it is safe.
What happens afterward. Once the house is cleared, the leak gets located and repaired, and that is when an HVAC company matters. If the source was the furnace, we test the gas valve, connections, and burner assembly, measure combustion and carbon monoxide, and put the findings in writing. If it was a line outside the equipment, that belongs to the utility or a plumber and we will tell you so rather than invent work.
Other heater smells, quickly. Not every smell is gas:
- Burning dust for the first few minutes of the season is normal and clears. The longer version: why does my furnace smell like burning.
- A sharp electrical or fishy smell that lingers can mean overheating wiring or a failing component. Shut the system off and call.
- A musty smell is usually the coil or ductwork, not the furnace burner.
- A smell that comes with a headache, nausea, or drowsiness in more than one person is a carbon monoxide pattern. Get out and call 911, and see do I need a carbon monoxide detector with a gas furnace, because California requires one.
No charge for the phone call. If you are standing in the driveway unsure how serious it is, call us and we will tell you honestly whether it sounds like a 911 situation or a service call. That advice costs nothing.
Everyone outside first. Then call us.
Gas smell is a safety call before it is a repair call. Once the gas company has made the house safe, we find what let the gas out and fix it, at a written price.
Every heating visit we make includes a combustion and carbon monoxide check.