A sealed battery, a stated lifespan, and a standard printed on the back
A carbon monoxide alarm is the only appliance on this site whose whole purpose is to report that something in the flue has gone wrong. It is judged on published figures and on nothing else here. The sensor lifespan is the first: electrochemical cells age whether or not they ever see gas, and every alarm on this shelf states a life — seven years and ten years are the two common answers — after which the unit is replaced, not serviced. The battery follows from it: a sealed ten-year cell means no battery changes and no battery to forget, a replaceable cell means a cheaper unit and an annual task. The declared standard is printed on the back of every legitimate device and is the single most useful thing on the listing. The alarm thresholds — the concentrations in parts per million and the time each must persist before the alarm sounds — are published by the better makers and are what separates a device that cries at a candle from one that waits too long. Then the display, which shows the current reading rather than only the alarm state, and the end-of-life signal, because an alarm that expires silently is worse than none. We compare alarm threshold, alarm level, sensor type, sensor life, battery, display, detection area, standard named, dimensions and mounting.
10-year sensor, 3-year AA batteries, LCD, 85 dB, EN 50291
A ten-year sensor with three-year AA batteries and an LCD, naming EN 50291 in its own title — the cheapest listing in this family.
Best for: A first alarm where the standard being named matters more than the extra features
Sealed 10-year battery, Ø 120 mm, 178 g, EN 50291-1 and -2
Names both parts of the standard, publishes its diameter and weight, states where it is made — and warns that the manual is German only.
Best for: A house with a stove where a fit-and-forget device with a named boat approval is wanted
7-year sensor, 60 m², alarms from 30 ppm, −10 to +40 °C, EN 50291-1:2018
The only listing here to publish a sensor life shorter than ten years — seven — alongside an operating temperature range and a 60 m² area.
Best for: A larger room, or an unheated space where the operating temperature range is the binding figure
10-year sensor, 2 × AA, 120 × 73 × 35.5 mm, EN 50291-1 and -2
Names two standards — the domestic one and the one for vehicles and boats — and publishes what each display code means.
Best for: A household that also uses a caravan or a boat and wants one device that names both standards
10-year device life, replaceable AA, 3-colour LED, 85 dB, EN 50291
A ten-year device life with replaceable AA cells, a three-colour status LED and EN 50291 named — with caravans and holiday homes stated.
Best for: A second or third device for a cellar or garage, where the cost of maintaining batteries is acceptable
Sealed 10-year battery, 23–999 ppm, LCD, >85 dB, EN 50291
A sealed ten-year battery with a detection range published as a span — 23 to 999 ppm — and EN 50291 named in the title.
Best for: A household that would rather replace a device once than remember batteries three times
10-year sensor, 20–40 m², detects from ~27 ppm, 3 × AA, 85 dB
Publishes a detection area, a detection threshold in ppm and a monthly test procedure — the most operationally complete listing here.
Best for: A room where the coverage area is the question and the device should say when it is wrongly installed
10-year life, 3-year AA, 75 × 142 × 32 mm, TÜV Rheinland certified
Publishes its own dimensions and states plainly what it is not — no app, no base station — with the model codes for those variants.
Best for: A buyer who wants a plain detector and needs to be sure they are not buying the connected variant
Sealed 10-year battery, alarms from 50 ppm, >85 dB at 3 m
States its alarm threshold, its sound level at a stated distance, and names the appliances it is intended for — stoves and pellet stoves among them.
Best for: A room with a wood or pellet stove, where the appliance being named in the listing is reassurance worth having
Only the specifications at least four models out of five state. A column that is more empty than full compares nothing.
| Model | Price | Alarm level | Alarm threshold | Amazon reference | Battery |
|---|
Specifications: manufacturer sheets and Amazon product pages. Prices and availability: Keepa. No product on this site has been physically tested.
Most recent revision in this category: September 22, 2026.
