Smoke and Carbon Monoxide Detector Alarms
Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is slightly less dense than air. Breathing it in, can make you sick and unwell, and will kill you when exposed to high levels. It disrupts the action of of your blood’s ability to carry oxgen, thereby causing the death of cells, and eventually can cause death.
In correctly burning fuel appliances such as gas boilers, oil boilers or solid fuel boilers, carbon monoxodide levels are well below any actionable levels. In an appliance that has not been maintained or working according to manufacturers instructions, carbon monoxide levels can start rising and be pumped into areas in which people live or sleep.
It is in areas of high risk, or near fuel burning appliances, where carbon monoxide detectors can potentially save lives and prevent long term health complications due to prolonged levels of exposure. A standalone or combined detector can be a very small price to pay in order to save lives.
Smoke and Carbon Monoxide Detector Alarms.
It is a part of building regulations that certain measures are required under certain circumstances. For example, when you are letting out a property on rent, smoke alarms are required on all levels where there is a room that is used for living accomodation purposes. In addition, heat alarms may be required in the kitchen.
A carbon monoxide alarm is mandatory if there is a solid fuel burning appliance in the room which is used wholly or partly as a living accomodation. In other cases carbon monoxide alarm detectors may be required by certain organisations when open flued gas appliances are present, that is however not mandatory in uk, although this may change.
Scotland has different rules regarding this, in that rented properties with any type combustion appliance requires a carbon monoxide alarm detector 1-3 meters from the appliance. It should not be place in a dead zone, that is within 300mm from the ceiling edges.
Intelligent and Smart Carbon Monoxide Detector Alarms
Since the last couple of years, there has been an increase in Smart connected Detectors. Companies such as Nest have completely changed the design of Smoke and Carbon Monoxide alarms or detectors. They come with a raft of features as simple as voice, ranging to additional guided lights and auto testing.
Even some of these products such as the Nest Protect, link up with your Smart Nest Thermostat, and shut the appliance down in the event carbon monoxide or smoke is detected. These alarms tend to have very sophisticated modern sensors, with the ability to distuingish between steam or smoke.
Carbon Monoxide Detector Alarm Placement

The detector should be, placed in every room with a fuel burning appliance. As stated in local laws and regulations, it is mandatory when certain types of fuel burning appliances are present, such as solid fuel appliances or solid fuel boilers. It is also generally highly recommended where open flued appliances such as Open Flue boilers are present.
- It is recommended to be placed a minimum of 1m upto a maximum of 3m away from the appliance.
- Avoid dead spaces, ie 300mm horizontally from the ceiling edge and 100mm vertically from the wall edge
- Mains powered detectors should adhere to electrical standards also. Search for prescribed electrical zones.
- Should have a clear path from appliance to the detector ie not placed inside a cupboard etc.
- Alarm should be tested regularly and/or annually. Some detectors, as stated earlier can perform auto testing.

Some manufactures may have their own product specific placement guidelines. Example above shows the Nest Protect placement guidelines. Usually in this industry, manufacturer’s guideline will exceed or override general guidelines. Manufacturer’s guideline should always be followed. See the installation manual for your specific detector.
Shown below is a comparison of smoke and carbon monoxide detector alarms.
Brand | Model | Url | Lowest price | Smoke / Carbon Monoxide CO | Sensor Life / Unit Life | Batteries /Battery Life | Key Features |
---|---|---|---|---|---|---|---|
Kidde | 7COC | Product Page | £13.18 | Carbon Monoxide CO | 10 year sensor | 3 x AAA Included | - |
Kidde | 7DCO | Product Page | £18.64 | Carbon Monoxide CO | 10 year sensor | 3 x AAA Included | LCD Screen |
Kidde | 10SCO | Product Page | £16.19 | Smoke and Carbon Monoxide CO | 10 year warranty | 9V battery (1-2 years) | Voice |
Kidde | 10LLDCO | Product Page | £16.19 | Carbon Monoxide | LCD Screen | ||
Kidde | CO-9D | Product Page | £24.99 | Carbon Monoxide | 7 year warranty | 2 X 1.5 DC Battery | LCD Screen |
Honeywell | XC70 | Product Page | £17.55 | Carbon Monoxide CO | 7 years | Builtin 7 year life | - |
Honeywell | XC100 | Product Page | £23.01 | Carbon Monoxide CO | 10 Years | Builtin 10 year life | - |
Honeywell | XC100D | Product Page | £30.32 | Carbon Monoxide CO | 10 Years | Builtin 10 year life | LCD Display |
Fireangel | CO-9B | Product Page | £12.60 | Carbon Monoxide CO | 1 Year battery Included | - | |
Fireangel | CO-9X | Product Page | £15.70 | Carbon Monoxide CO | 7 years | Builtin 7 year life | - |
Fireangel | CO-9D | Product Page | £21.50 | Carbon Monoxide CO | 7 years | Builtin 7 year life | LCD Display |
Nest Protect | Protect v2 | Product Page | £89 | Smoke and Carbon Monoxide CO | 10 Years | Mains / Battery | Smart Device |
Nest Protect | Protect v2 | Product Page | £89 | Smoke and Carbon Monoxide CO | 10 Years | Battery | Smart Device |
The following table shows the exposure levels and it’s health effects.
CO Level ppm | Conditions and Health Effects | Institute |
---|---|---|
0 | Normal, Fresh Air | |
9 | Maximum allowable short term exposure | ASHRAE |
10-24 | Possible health effect with long-term exposure | |
25 | Max TWA exposure for 8 hour work day | ACGIH |
50 | Maximum permissible | |
100 | Slight headache after 1-2 hours | |
200 | Dizziness, nausea, fatigue, headache after 2-3 hours of exposure | |
400 | Headache and nausea after 1-2 hours exposure/life threatening in 3 hours | |
800 | Headache, nausea, and dizziness after 45 minutes / Collapse and unconsciousness after 1 hour of exposure, death with 2-3 hours | |
1600 | Headache, nausea, and dizziness after 20 minutes , death within 1-2 hours | |
3200 | Headache, nausea, and dizziness after 5-10 minutes , death within 1 hour | |
6400 | Death within 30 minutes | |
12800 | Death within 1-3 minutes of exposure |