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Where to place a carbon monoxide detector – and nine other questions answered

Whether you’re  a landlord, tenant or homeowner, one of the most important devices to have in your property is a carbon monoxide alarm.

Carbon monoxide poisoning accounts for around 60 deaths in UK homes every year, yet is completely preventable.

One way to protect those living in your property is with a carbon monoxide alarm – and if you’re a landlord, you have to have these devices in any room of your rental property where a solid fuel burning appliance is located.

But what are carbon monoxide alarms, how do they work and why do you need one?

Here, we’ll answer all of those questions and many, many more…

1 What is a carbon monoxide detector?

A carbon monoxide detector is a device that detects the presence of carbon monoxide (CO) in the air and sets off an alarm to alert people.

Using various sensors, the alarms are triggered when CO levels reach a certain point.

  • Biomimetic sensors
  • A gel in the device changes colour when it absorbs CO, which triggers the alarm
  • Metal oxide semi-conductor sensor
  • CO compromises the electrical resistance of the device’s circuit, which trips the alarm
  • Electrochemical sensor
  • Electrical currents in a chemical solution inside the device change in the presence of CO and set off the alarm

2 Where to place a carbon monoxide detector

CO detectors should be placed in every room with a solid fuel-burning appliance, but also with gas or oil burning appliances, too.

If you’re a landlord, you are legally obligated to place a working CO detector in every room that burns solid fuel, with penalty fines of up to £5,000 for non-compliance.

Detectors should also be:

  • Placed at least 10 feet away from each fuel-burning appliance
  • Placed on a flat surface at head height
  • Kept out of cupboards and not placed behind furniture, outside of doors or close to extractor fans
  • Kept away from high-condensation areas like bathrooms or cooking hobs
  • Tested regularly, with batteries replaced when needed


3 Do I need a carbon monoxide detector?

If you’re a landlord, then you’re legally obliged to provide a working CO detector in each room that houses a solid fuel burning appliance.

Those appliances could include:

  • Coal fires
  • Wood-burning stoves   

While it’s not a legal requirement to provide a CO detector for gas-burning appliances, like boilers and gas fires, it is recommended that landlords do this, as these appliances can also emit CO.

For homeowners, CO alarms should also be used in rooms where solid fuel is burned, but also where gas appliances are present, too.

4 Does a carbon monoxide detector detect gas?

CO detectors aren’t designed to detect gas leaks in properties.

While gas can generally be detected by sense of smell, CO is odourless, which is why it’s dubbed a ‘silent killer’ and only the use of a CO detector can raise the alarm quickly.

5 Does a carbon monoxide detector go off continuously?

Most CO detectors will continue to sound their alarm until the level of CO in the air drops back to an undetectable level.

Most CO detectors beep four times followed by a pause and continue to do this while CO is present.

A short chirp every minute means your alarm’s batteries are running low and should be changed, while five beeps every minute means your alarm has reached the end of its life and needs to be changed.

6 Can carbon monoxide detectors go off for no reason?

The best assumption to make when your CO alarm goes off is that there is CO in the air.

CO detectors generally don’t go off for ‘no reason’ – it’s just a case of working out what the reason is.

Read your alarm’s instructions so you’re aware of what the different beep combinations mean.

That will help you determine whether your alarm is sounding because of CO, or because its batteries need replacing or it’s coming to the end of its life.

7 Do you need a carbon monoxide detector with oil heat?

Carbon monoxide can be produced from oil burning appliances, so it’s recommended you have a CO detector in all rooms where this is the case.

For landlords, there is no legal requirement to have a CO detector in rooms where gas or oil is burned – just solid fuels like wood or coal.

However, it’s recommended that you have CO alarms in all rooms where fuel is burned, regardless of legislation.

8 How long do carbon monoxide detectors last?

CO detectors generally last between five and seven years and should, as a rule, be replaced every five years.

During that time, CO detectors should be tested regularly, and the batteries changed when required.

9 How do you test if your carbon monoxide detector is working?

CO detectors have a test button, which should be used every month to be certain your alarm is functioning correctly.

You should also be able to clearly hear the alarm from all bedrooms in your property, for peace of mind that everyone would wake should the alarm sound during the night.

10 What does 888 mean on a carbon monoxide detector?

If you’re using a slightly more advanced CO detector that shows an air quality reading, you might see the figure 888 on the screen when you test the device.

This is not a reading and the number is shown purely for device testing purposes.


Staying compliant

The best way to stay compliant as a landlord is to use a trusted agent to manage your rental properties.

Carrick Johnson Lettings Fully Managed package, include full compliance with lettings safety laws and regulations – meaning total peace of mind for you and your tenants