Where should a propane leak detector be mounted, since propane sinks toward the floor?

Low on the wall, same room, not on top of the burner

The physics is simple: propane is denser than air, so it flows downhill and settles like invisible water. That means the detector belongs near the floor — most manufacturers specify somewhere in the bottom foot or so of the wall — in the room where the propane appliance lives. Follow the instructions that come with your specific detector; heights vary a little by model.

Don't mount it directly beside the firebox, though. Every gas appliance releases a tiny puff of unburned fuel at ignition, and a detector inches away will cry wolf until someone unplugs it — which defeats the whole exercise. A few feet of lateral distance keeps it honest. Avoid dead-air corners, spots behind furniture or drapes, and locations right at a doorway where drafts wash past.

Basements, crawl spaces, and cabin floors

Because propane flows downhill, the lowest level of the house is where a leak ends up. In the propane homes we serve around Fairview, Candler, Brevard, and the cabins on our mountain roads, that usually means the basement or crawl space under the hearth room. If your fireplace sits on a main floor over a basement, a second detector down there is money well spent. And propane cylinders themselves never belong indoors — the house tank stays outside for exactly this reason.

Three alarms, three different heights

It helps to keep the family of detectors straight. Propane detector: low, near the floor. Natural-gas detector: high, because natural gas rises. Carbon monoxide alarm: per its manufacturer — CO mixes with room air rather than strictly sinking or rising, so placement rules differ by brand. No one of these substitutes for another.

If any of them ever sounds — or you smell gas at all — leave the house without flipping switches, and call from outside. We're a licensed gas contractor and we answer 24/7 at (828) 545-0525; we can pressure-test the system and find the source.