Natural gas is methane, it rises, and it is odorized so you can smell it, but only when you are awake and in the room. These detectors were chosen from manufacturer specifications for a home on a natural gas supply, with notes on the one placement rule that most buyers get wrong.
Methane Rises
Mount High
Back It Up
These picks are for a home supplied with natural gas (methane). They were compared on gases covered, listing standards, power backup and display, using manufacturer documentation and owner feedback; no laboratory testing was carried out.
Natural gas, propane and CO from one listed plug-in.
Third-edition Kidde plug-in with a 9V backup and event memory.
Plug-in monitor with a live ppm reading plus temperature and humidity.
No pick matches that combination yet. Try a wider budget or a different measurement.
| Product | Gases | Display | Power | Alarm | Listing / Notes | |
|---|---|---|---|---|---|---|
| Kidde COPDLG | Natural gas, propane, CO | CO ppm or GAS | 120V + 2 AA backup | 85 dB | UL 2034 5th Ed, ETL; replaces KN-COEG-3 | View |
| Kidde CO + Explosive Gas (9V) | Natural gas, propane, CO | CO ppm or GAS, peak memory | 120V + 9V backup | 85 dB | 3rd Edition | View |
| Orabal 4-in-1 | Natural gas, methane, propane, LPG | Live ppm, temp, humidity | 120V, no backup | 85+ dB | No listing stated | View |
| TopTes PT520A (handheld) | Methane, propane, butane, LPG | 7 bars | 3 AAA | 75 dB | Locator, not an alarm | View |
| TopTes PT199 (handheld) | Methane, propane, butane, LPG | Red screen on alarm | 2 AAA | Audible | 50 to 1,000 ppm; locator | View |
Manufacturer-published specifications at the time of research. Only the fixed alarms are intended for continuous monitoring; the two handhelds are included for finding the leak afterwards.
Methane behaves differently from propane, and the detector has to match:
Methane rises. A dedicated natural gas detector belongs within about a foot of the ceiling; a plug-in at an outlet is a compromise the manufacturer must approve.
UL 1484 for gas, UL 2034 for CO. It is the only evidence that the alarm threshold and false-alarm resistance were checked.
Outages and furnace failures often coincide. A plug-in without backup is off when you need it.
Any gas appliance can produce carbon monoxide. A combination alarm covers both hazards in one outlet.
Methane is lighter than air, so a dedicated natural gas detector is mounted high on the wall, generally within about 12 inches of the ceiling, in the room with the appliance. Plug-in combination alarms sit at outlet height because the manufacturer has designed and listed them for that position. Follow the manual for the specific model.
The Kidde and Orabal units listed here detect both. The catch is placement: propane sinks, so a ceiling-mounted methane detector will be slow to see a propane leak at floor level. If your home uses propane, see the propane detector guide.
Raw methane is odorless. Utilities add mercaptan, which smells like rotten eggs or sulfur, so leaks can be noticed. A detector matters for the times you are asleep, away, have a reduced sense of smell, or the odorant has faded in a long pipe run.
Use the test button for the alarm circuit. Holding an unlit butane lighter near the sensor will usually trip the combustible sensor, but do it briefly, in a ventilated room, and never with a flame. Kidde and most manufacturers describe the approved method in the manual.
For a natural gas home the COPDLG is the sensible default because a house with a gas furnace or water heater has two risks, not one: a supply leak (methane) and a combustion problem (carbon monoxide). One plug-in covers both, and the display tells you which has tripped.
Kidde lists it as the replacement for the KN-COEG-3 and 900-0113, which have been the standard hardware-store gas alarm for years, so mounting and behavior are familiar. The AA backup keeps it running through an outage, which matters because a furnace blower stopping is exactly when a flue problem can appear.
The compromise is height. Methane collects at the ceiling, and an outlet is near the floor. Kidde accepts outlet mounting, and in a kitchen with an eight-foot ceiling the difference is small; in a tall utility room, or if you want a methane-only alarm at the ceiling, pair it with a ceiling-zone detector.
This is Kidde's other plug-in combination alarm, the third-edition model with a 9V backup battery instead of AA cells. Function is the same: it samples for explosive gas and carbon monoxide, shows the CO reading in ppm and switches the display to GAS when the combustible sensor trips, with an 85 dB horn.
The feature that sets it apart is Peak Level Memory, which stores the highest CO reading since the last reset. If the alarm sounded while you were out, or a low-level CO event resolved itself when the furnace cycled off, you can still see that it happened, which is the kind of evidence a technician needs.
Choose the COPDLG if you want AA backup and the newer low-level CO alert pattern; choose this one if the peak memory matters to you or the 9V version is what your local store stocks. Either way, keep it in the room with the appliance, not in a bedroom.
The Orabal is here for one reason: it shows a live gas concentration in ppm rather than a silent standby, so you can see a small rise when the oven igniter takes a few seconds too long, and see it fall again. That is useful information that a listed alarm, which stays quiet until its threshold, does not give you.
The listing states continuous monitoring of natural gas, methane, propane and LPG, a preset alarm threshold with an 85+ dB horn and flashing display, and a brief warm-up after plugging in. It also shows temperature and humidity.
What the listing does not state is any UL 1484 or ETL listing, and there is no battery backup, so it goes dark in an outage. Treat it as a monitor that complements a listed alarm rather than as the alarm itself. Used that way, it is the cheapest way to make a methane leak visible before it becomes audible.
Short answer: for a home on natural gas, plug a Kidde COPDLG into an outlet in the room with the furnace, water heater or range. It is listed, covers methane, propane and carbon monoxide, and keeps running on AA backup. If you want to watch the level rather than wait for an alarm, add an Orabal 4-in-1 monitor; if you want the peak-memory feature, the 9V-backup Kidde is the equivalent alternative.
Natural gas is 85 to 95 percent methane. Residential detectors use a semiconductor or catalytic sensor that responds to combustible gas in general, then set the alarm at a fraction of methane’s lower explosive limit, which is about 5 percent by volume. Because the sensor is not gas-specific, the same alarm usually also responds to propane and butane; what changes between a “natural gas” and a “propane” model is the mounting position the manufacturer designed it for. How gas leak detectors work covers the sensor types.
Methane is lighter than air. A leak from a range connector or a furnace valve rises and spreads along the ceiling before it fills the room downward. A detector at the ceiling sees that early; one at the floor sees it last. This is why the Kidde plug-ins, which live at outlet height, are a compromise: Kidde has designed and listed them for that position, and in a normal-height kitchen the delay is small, but the physics favors the ceiling. For the full set of rules, including distance from the stove, vents and windows, read where to place a natural gas detector and does natural gas rise or fall.
A home with gas appliances has two risks: the gas itself leaking, and the appliance producing carbon monoxide when combustion goes wrong. The two Kidde units cover both from one outlet and their display says which one has tripped. A dedicated methane-only alarm at the ceiling is the better sensor position but does nothing for CO, so most homes end up with either a combination unit or a pair. Gas leak detector vs carbon monoxide detector explains why the sensors cannot be merged.
UL 1484 is the residential gas detector standard. A listed alarm has had its trip level, resistance to nuisance alarms and long-term sensor drift checked by a laboratory. The Orabal monitor in our picks is useful precisely because it shows a live reading, but its listing does not state a certification, so we place it as a supplement. The generic ten-year-battery plug-ins on the marketplace fall into the same category.
A fixed alarm does not tell you which joint failed. That is a job for a handheld sniffer with a gooseneck, held near each fitting once the utility has said the building is safe. The handheld gas leak detector guide compares them; the TopTes PT520A in the table above is the usual recommendation for a homeowner. Our how-to-choose article covers the decision in more depth, and the main gas leak detector guide covers propane and RV cases.
Selection was based on manufacturer documentation (gases detected, display, power and backup, listing standards, warranty) and recurring owner feedback on false alarms and longevity. We did not run laboratory tests. Amazon data supplies images, availability and links only.
Mount a natural gas detector high, within about 12 inches of the ceiling, in the room with the gas appliance, away from the range, vents and windows.
Read Guide→No. A CO detector cannot sense natural gas, propane or methane, and a smoke detector cannot either. Only a combustible gas sensor responds to a fuel leak.
Read Guide→A gas leak detector senses unburned fuel before it can ignite; a CO detector senses the poison left by fuel that burned badly. Neither covers the other.
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