Key takeaways
- Maker states a 10-year product and battery life
- ETL listing to UL 1484 stated by DeNova
- Compact 3.8 inch wide body mounts high
Because a carbon monoxide alarm cannot sense unburned methane, a dedicated natural gas detector fills a gap that smoke and CO devices leave open, and the right one depends on power, mounting and a real safety listing.
Quick Verdict: For a straightforward methane alarm, the DeNova Detect DD620NV is the pick because its maker states an ETL listing to UL 1484 and a sealed 10-year battery at $96.99. If you also want carbon monoxide coverage, the DeNova Detect DD623NCV adds it for a few dollars more. This is an editorial pick based on published specifications as of October 2026, not in-house testing. Check the current price and confirm the gas listing on the product page before you buy.
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By DIY Ideas 4 Home Editorial Team
The Best Natural Gas Detectors Reviewed
We selected these based on published specifications and manufacturer documentation rather than in-house testing, weighing each model’s stated gas listing, power type and mounting guidance as of October 2026. Residential gas alarms here run roughly $60 to $105 at major retailers, and because only five models carried clear methane documentation and a named price, we did not stretch the set to a sixth.
| Product | Best For | Key Spec | Listed Price (as of October 2026) | Watch Out For |
|---|---|---|---|---|
| DeNova Detect DD620NV | Battery-only methane alarm | 10-year battery, ETL to UL 1484 stated | $96.99 | Not a carbon monoxide alarm |
| DeNova Detect DD623NCV | Methane plus carbon monoxide | Dual listing to UL 1484 and UL 2034 stated | $103.98 | Do not substitute the older DD622NCV |
| Kidde COPDLG 21033781 | Plug-in with outage backup | Methane, propane and CO, 85 dB | $61.97 | Placement differs by fuel type |
| Kidde Firex 900-0113 | Legacy plug-in combination | Explosive gas plus CO, 9V backup | $68.99 | Older SKU, confirm availability |
| Shelly GAS CNG | Connected natural-gas alert | Wi-Fi alerts plus local siren | $69.99 | UL 1484 record not retrieved |
DeNova Detect DD620NV: Best For a Battery-Only Methane Alarm
Best For: Homeowners who want a dedicated natural-gas alarm that mounts anywhere without needing an outlet.
Against the plug-in models here, the DD620NV wins the top slot by pairing a stated safety listing with a sealed decade-long battery, so placement is driven by where methane collects rather than where a receptacle sits.
The DD620NV product page from DeNova states the unit is a methane and natural-gas alarm listed by ETL to UL 1484, with a 10-year integrated battery, a MEMS sensor and a maker-claimed 10 percent lower explosive limit trigger, priced at $96.99 as of October 2026.
The alarm’s body measures 3.8 inches wide and 1.6 inches deep, a compact square that mounts high where methane rises. Its honest limitation is scope: it is not a carbon monoxide alarm, and the maker’s early-warning and lower explosive limit claims are stated by DeNova rather than independently measured by this site.
Pros:
- Maker states a 10-year product and battery life
- ETL listing to UL 1484 stated by DeNova
- Compact 3.8 inch wide body mounts high
Cons:
- Does not sense carbon monoxide
- Costs more than a plug-in Kidde
Who Should Buy It: Buy the DD620NV for methane-only protection; if you want gas and carbon monoxide in one unit, choose the DeNova Detect DD623NCV instead.
DeNova Detect DD623NCV: Best For Methane Plus Carbon Monoxide
Best For: Homes that want one sealed, battery-powered device covering both natural gas and carbon monoxide.
Compared with the methane-only DD620NV, this model folds in CO sensing, so it is the pick when you would otherwise buy two alarms, at a small price step up.
The DD623NCV product page from DeNova states the device senses natural gas and carbon monoxide, with ETL listing to both UL 1484 and UL 2034, a 10-year integrated battery and the same 10 percent lower explosive limit threshold claim, at $103.98 as of October 2026, which is $6.99 over the DD620NV.
Like its sibling, the DD623NCV measures 3.8 inches wide and 1.6 inches deep, so mounting height still follows the gas it is watching for. Two cautions apply: the maker’s own storefront has shown it sold out, and the earlier DD622NCV carries a separate safety replacement notice, so confirm the DD623NCV model on the packaging and never substitute the older unit.
Pros:
- Senses both natural gas and carbon monoxide
- Dual listing to UL 1484 and UL 2034 stated
- Sealed 10-year battery design
Cons:
- Maker storefront has shown it out of stock
- Costs more than the methane-only DD620NV
Who Should Buy It: Pick the DD623NCV to cover both hazards in one alarm; if a wall outlet and outage backup matter more, look at the Kidde COPDLG 21033781 instead.
Kidde COPDLG 21033781: Best For Plug-In With Outage Backup
Best For: Rooms with a spare receptacle where a three-gas plug-in with battery backup is the simplest install.
Unlike the sealed DeNova alarms, the Kidde plug-in draws from the wall and keeps watching during an outage on backup cells, which is its main appeal over a battery-only unit.
Kidde’s COPDLG product page confirms it alerts to natural gas, propane and carbon monoxide with an 85 decibel signal, uses two AA backup batteries, and lists at $61.97 as of October 2026, with an optional cord so the methane sensor can sit near the ceiling.
Kidde’s data sheet lists the COPDLG at 2.9 inches wide and 5.47 inches tall, weighing 0.50 pound, a vertical plug-in body. Its catch is placement: natural gas is monitored high while propane settles low, so the correct mounting height depends on the fuel, and it is not a stand-alone smoke alarm.
Pros:
- Covers natural gas, propane and carbon monoxide
- Two AA cells for outage backup
- Vertical 5.47 inch tall plug-in body
Cons:
- Needs a suitable receptacle or cord routing
- Fuel-specific placement guidance differs
Who Should Buy It: Choose the COPDLG for a plug-in with backup; shoppers who prefer a sealed battery alarm should take the DeNova Detect DD620NV instead.
Kidde Firex 900-0113: Best For a Legacy Plug-In Combination
Best For: Buyers replacing an older wired-in Firex gas and CO unit who want a like-for-like plug-in.
Set beside the newer COPDLG, the Firex is an established combination unit with a 9-volt backup rather than AA cells, which is why it suits a straight replacement more than a first install.
The Firex 900-0113 listing describes an explosive-gas alarm for natural gas and propane plus carbon monoxide, plug-in with a 9-volt battery backup, priced at $68.99 as of October 2026, though the exact backup behavior should be confirmed against the model manual.
The Firex 900-0113 measures 6.1 inches long and 3.8 inches wide per its specification sheet, with a 1.8 inch depth, a wider body than the DeNova alarms. Its weak points are age and paperwork: it is an older SKU whose current stock can be uncertain, and its UL 1484 register entry was not independently retrieved here.
Pros:
- Combines explosive gas and CO sensing
- 9-volt battery backup reported
- Wider 6.1 inch long body
Cons:
- Older SKU with uncertain availability
- Gas listing register not retrieved in this research
Who Should Buy It: Buy the Firex 900-0113 mainly as a direct replacement; for a current connected option, consider the Shelly GAS CNG instead.
Shelly GAS CNG: Best For a Connected Natural-Gas Alert
Best For: Smart-home users who want a phone notification on top of a local methane alarm.
Against the standalone alarms here, the Shelly adds Wi-Fi alerting, so it suits someone who wants to know about a leak while away, with the trade-off of network dependence for the remote part.
Shelly’s product page names a CNG, or natural-gas, option distinct from the LPG variant, pairing Wi-Fi notifications with an audible and LED local alert on a 120-volt plug-in, listed at $69.99 as of October 2026.
The Shelly GAS measures about 89.5 millimeters, roughly 3.5 inches, wide and 38 millimeters deep excluding the plug, a small square body. Its limitation is certification: the maker calls the product certified, but a UL 1484 model record was not retrieved in this research, so treat the local siren as the primary protection and the app as a convenience.
Pros:
- Wi-Fi alerts plus a local siren
- Distinct methane CNG model
- Compact 89.5 millimeter wide body
Cons:
- UL 1484 listing not retrieved in this research
- Remote alerts depend on the network
Who Should Buy It: Pick the Shelly GAS for connected alerts; if a documented safety listing matters most, the DeNova Detect DD620NV is the stronger choice.
How to Choose a Natural Gas Detector
Methane safety rewards matching the device to the fuel and the listing, not to the longest feature list. Four questions guide the choice.
Check Methane Detection and the UL 1484 Listing
Confirm the device is a fuel-gas alarm and look for a UL 1484 listing, the residential standard for gas detection, which is different from UL 2034 for carbon monoxide and UL 217 for smoke. A listing a seller merely states is weaker evidence than a retrievable registry record, so prioritize documentation here.
Match the Alarm Type and Mounting Height
Mounting follows chemistry. Natural gas, mostly methane, rises and is monitored high, while propane is heavier and collects low, so a single alarm cannot be placed the same way for both fuels. Set the device by the fuel in your home and the printed model manual.
Decide Between Battery and Line Power
Weigh a sealed battery alarm against a plug-in with backup. The DeNova units mount anywhere on a 10-year cell, while the Kidde plug-ins run on house power with AA or 9-volt backup during outages. Prioritize line power with backup if you want continuous operation near a known source.
Confirm the Price and Exact Model Source
Pin the price to the exact model and date. The DD623NCV at $103.98 sits $6.99 above the DD620NV, and the plug-in Kidde COPDLG at $61.97 is the lowest here, but a plug-in and a sealed alarm are not the same purchase, so compare like with like. The US CPSC fact sheet and your gas utility are the right references for safe response.
Frequently Asked Questions
These answers cover the safety questions gas-alarm buyers ask most.
Does a carbon monoxide alarm also detect natural gas?
No. Carbon monoxide and methane are different hazards sensed by different technologies. A CO alarm will not warn you about unburned natural gas, which is why a dedicated gas alarm or a documented combination unit is needed.
What should I do if the gas alarm sounds?
Leave immediately and do not touch light switches, outlets, flames or a phone while indoors. Once outside, call 911 or your gas utility, and do not re-enter until responders say it is safe.
Where do I mount a natural gas detector?
Because methane rises, natural-gas alarms generally mount high on a wall or near the ceiling, following the model manual. Propane alarms are different and mount low, so never assume one height fits both fuels.
Is UL 1484 the same as the CO or smoke standard?
No. UL 1484 is the residential fuel-gas detection standard, UL 2034 covers carbon monoxide and UL 217 covers smoke. Checking the right marking for the hazard is part of choosing correctly.
Final Thoughts
For most homes the DeNova Detect DD620NV remains the pick because a stated UL 1484 listing and a sealed 10-year battery make placement simple, though buyers who want carbon monoxide too should step up to the DD623NCV and connected-home users may prefer the Shelly GAS; before you order, confirm the exact model’s gas listing on the product page and match the mounting height to your fuel.
