When we think about home safety, smoke alarms often get all the attention. However, if your home has a wood burning stove, solid fuel appliance, or gas fire, there is another safety device that is just as important. If not more so: a carbon monoxide (CO) alarm.
Carbon monoxide is often referred to as the silent killer, and for good reason. It is colourless, odourless, and invisible, meaning it cannot be detected without a suitable alarm. Any appliance that burns fuel including gas, wood, coal, or pellets has the potential to produce CO if something goes wrong.
UK building regulations require a CO alarm to be installed for any solid fuel or gas appliance in order for the installation to be HETAS or Gas Safe certified. CO alarms are particularly important in homes with gas fires or gas stoves, as gas does not produce smoke or smell in the same way solid fuel does. With solid fuel, smoke or fumes may provide an early warning that something is wrong, whereas CO from gas appliances can build up unnoticed.
Carbon Monoxide and Solid Fuel Appliances
Carbon monoxide is produced when solid fuels such as wood, coal, or smokeless fuels do not burn completely. When a stove is operating correctly with adequate airflow, combustion should produce mainly carbon dioxide (CO₂). A CO alarm can alert you if one or more of the following issues occurs, allowing action to be taken before safety is compromised:
- Incomplete Combustion – CO can build up when there is insufficient oxygen for the fuel to burn properly. This may happen if air vents are closed too far, the stove is run in “slumber” mode for long periods, or the firebox is overloaded.
- Blocked or Restricted Chimney or Flue – A clear flue is essential for safely removing combustion gases. Soot, tar, creosote, bird nests, or debris can restrict the flue, causing CO to spill back into the room. This is why regular chimney sweeping is essential.
- Poor Chimney Draw – Even a clear chimney can suffer from poor draw, particularly with cold flues at start-up or during adverse weather conditions. Downdraughts can prevent fumes from exiting correctly, leading to smoke and CO entering the room.
- Lack of Maintenance – Without routine servicing, air controls may not function correctly and components such as door rope seals can deteriorate, increasing the risk of CO production.
- Unsuitable or Wet Fuel – Burning fuel with a high moisture content, such as wet or unseasoned wood, leads to cooler, inefficient combustion and increased CO production. Only approved fuels should be used, and wood should have a moisture content below 20%.
Carbon Monoxide and Gas Appliances
As with solid fuel, carbon monoxide can be produced when gas does not burn completely. In a correctly installed and maintained gas appliance, combustion should produce carbon dioxide (CO₂) and water vapour. A CO alarm will alert you if issues arise, including:
- Incomplete Combustion – This can occur if burner ports are blocked or dirty, the air-to-gas ratio is incorrect, or the appliance is faulty or poorly adjusted.
- Chimney or Flue Issues – Although gas fires do not produce soot, chimneys and flues still require regular sweeping and smoke testing, ideally once a year. Chimney performance can also be affected by downdraughts which can cause combustion gases and CO to spill back into the room.
- Lack of Servicing and Maintenance – Over time, burners can degrade, seals can fail, and heat exchangers can deteriorate. These faults may allow CO to escape into living spaces. Annual servicing by a Gas Safe registered engineer is essential to ensure all safety checks are carried out.
Our Commitment to Safety
At Stonewoods, safety is paramount. We will not complete any stove or gas fire installation without a carbon monoxide alarm in place. The risks of not having one simply are not worth taking, and a CO alarm provides vital protection and peace of mind for you and your family.