What to do if my Carbon Monoxide alarm goes off?

CO detectors, or carbon monoxide alarms, are essential for the detection of a deadly gas, carbon monoxide (CO). This gas cannot be seen, tasted or smelt and is only detected with the use of co detectors. It is produced through the incomplete combustion of fuel, such as gas, wood, coal and oil. If your carbon monoxide alarm is going off, do not assume it is a false alarm.

What to do when your carbon monoxide alarm is going off

You should assume that there is CO present and should follow these steps to ensure your safety.

  • Stay calm, open doors and windows to increase ventilation
  • Where safe to do so, turn off any fuel-burning appliance
  • Leave the premises and notify other occupants of the potential carbon monoxide leak (you should also notify any occupant of premises adjoined to your home as CO can seep through walls and floors
  • Call Gas Emergency Services 0800 111 999 or a local Gas Safe Registered Engineer to check for the source of carbon monoxide
  • Get medical help for anyone suffering from symptoms of CO poisoning

Symptoms of carbon monoxide poisoning

The main symptoms of carbon monoxide poisoning are:

Carbon monoxide poisoning symptoms: persistent headaches

Persistent Headaches

Having persistent dull headaches and tension type headaches.

Carbon monoxide poisoning symptoms: dizziness

Dizziness

Having waves of dizziness or feeling light headed and off balance.

Carbon monoxide poisoning symptoms: nausea/vomiting

Nausea / Vomiting

Feeling like you need to be sick (nausea) and actually being sick (vomiting).

Carbon monoxide poisoning symptoms: stomach pains

Stomach Pains

Pains in your stomach or lower abdomen, sometimes accompanied by diarrhoea.

Carbon monoxide poisoning symptoms: difficulty breathing

Difficulty Breathing

Sudden shortness of breath or difficulty breathing (dyspnoea).

Carbon monoxide poisoning symptoms: tiredness

Tiredness

Having no energy or feeling tired, sleepy, lethargic and sluggish.

Carbon monoxide poisoning symptoms: sudden collapse

Sudden Collapse

Sudden collapse, seizures or loss of consciousness.

Carbon monoxide poisoning symptoms: confusion

Confusion

Confusion, difficulty concentrating and becoming easily irritated.

What causes CO detector false alarms?

A false alarm is when your CO detector alarms and where no carbon monoxide is detected by your engineer. There could be several reasons for this, which can often be easily resolved:

Cause of alarmWhat to do
The carbon monoxide detected did not come from your own appliances but may have seeped through the walls or floor from a neighbour.Check if your neighbours have fuel-burning appliances that might emit carbon monoxide. Carbon monoxide might escape from chimney stacks allowing the toxic gas to enter your premises via a joint loft space.
The replace-by date may have been exceeded.Most CO alarms are only effective for 5-10 years. Once expired, they can sound erratically, or not sound when they should, The expiry date for each unit can be found on the information sticker on the back of the unit.
Excessive moisture from a bathroom may set off your CO alarm.CO alarms can be corrupted by steam, and therefore shouldn’t be installed in bathrooms. If your CO alarm is repeatedly triggered by steam, it may become ineffective, and should be replaced.
Lead acid battery chargers produce hydrogen gas which sets off CO detectors.If you are charging your caravan or boat battery at home, this could set off your CO alarm. Once you have made sure that the alarm is false, it is safe to ignore the alarm in this scenario, but remain vigilant for other signs. If this happens often, invest in a CO alarm with a digital display to assess the level of risk when the alarm sounds.
Freshly screeded floors emit a gas that sets off carbon monoxide alarms.If your floors have just been screeded, and you have made sure that the alarm is false, it is safe to ignore the alarm in this scenario, but remain vigilant for other signs.
The carbon monoxide alarm that you have installed may not be suitable for the type of premisesFor example if it is installed in a caravan, tent, boat or living quarters of a horsebox you will need to ensure that your alarm is Kitemarked to BS EN50291-2. Alarms tested to BS EN50291-1 are only for use in home environments and are not suitable for camping and caravanning.
Smoking indoorsA heavy smoker in a poorly ventilated room the CO from smoking may trigger an alarm. It is recommended to open a window if possible to improve ventilation. If this happens often, invest in a CO alarm with a digital display to assess the level of risk when the alarm sounds.
Homes that are adjacent to very busy roads may experience higher levels of CO in the home when windows are open as traffic fumes may enter the room and set your alarm off.If this causes persistent false alarms, invest in a digital CO alarm, allowing you to see a live CO reading. You can then determine the level of risk. For example, if the reading is high, there is probably a leak. However, if it has just tipped over the threshold due to air pollution, the alarm can be ignored/silenced without having to get an engineer in to check for a leak.
The sound that your alarm is making may not be the alarm sound to alert you that there are dangerous levels of CO present.Most alarms have several audible sounds to indicate things such as low battery warning or that there is a fault with the alarm. Keep the manual safe so that you can refer to it should the alarm go off.

Buying a CO detector

You should have a carbon monoxide detector in every room where there is a solid fuel burning appliance. Only chose CO detectors that have met the rigorous testing standards of the European standard EN50291. These alarms provide peace of mind that this vital alarm has been manufactured and tested to the highest standards. Moreover, investing in a CO detector with a digital display also provides peace of mind, as it allows you to assess the situation when an alarm goes off. This is particularly useful if you have had persistent false alarms due to pollution, smoking, or other external factors, as it allows you to check the reading to assess the level of risk before calling an engineer to check for a leak.

For more information about taking a carbon monoxide detector on holiday, read our blog on this ultimate travel essential, and what to do if you detect a leak.

Kidde Carbon Monoxide Alarm - 7DCO / 7DCOC
Kidde Carbon Monoxide Alarm - 7DCO / 7DCOC
  • Product Life: 10 years
  • Battery: replaceable AA alkaline batteries included
  • Warranty: 10 year warranty
  • Displays CO levels from 10ppm
  • Peak Level Memory - recalls highest CO levels
  • Ideal for domestic use and camping, caravans & boats
  • Kitemarked to BS EN50291-1 and BS EN50291-2
  • Also suitable for the 2022 Welsh legislation
£15.21 ex VAT
£18.25 inc VAT
Buy Now

If you are unsure if you have the correct carbon monoxide alarm installed our customer care team are here to help. You can call them on 0800 612 6537 or email support@safelincs.co.uk.

Angie Dewick-Eisele

Director

Angie Dewick-Eisele is co-founder of Safelincs Ltd, one of the leading fire safety providers in the UK. Angie was Marketing Manager for many years and as Director is these days responsible for Content Management.

Latest Posts by Angie Dewick-Eisele

Emergency Lighting Requirements1st August 2024
What to do if my Carbon Monoxide alarm goes off?19th March 2024
What is BAFE certification?28th March 2023

Why is my smoke alarm beeping?

Is your smoke alarm beeping in the night and keeping you awake, or disturbing your day? Whether you have mains powered, interlinked smoke alarms, or battery powered smoke alarms, follow our guidance below to troubleshoot the beeping.

What sound is your smoke alarm making?

Smoke alarm sounding continuously

  • First check there is no smoke or fire in your property
  • Make sure the beeping is definitely coming from your smoke alarm. Other alarms in the property such as a carbon monoxide alarm or burglar alarm could be responsible for the noise.
  • Clean the alarm if it is dusty or dirty. Vacuum around the alarm or use a hairdryer to blow out dust on a cool setting.
Replace by date on the back of a smoke alarm | smoke alarm chirping in the night
Replace by date on back of smoke alarm
  • Check the replace by or manufacture date on your alarm. Smoke alarms usually last for a maximum of 10 years, so if the manufacturing date is approaching 10 years or more than 10 years, it’s time to get a new smoke alarm. Sensors inside the alarm deteriorate after this time causing the alarm to be less effective.
  • Check the position of your alarm. There are different types of smoke alarm suitable for specific locations in your home. Find out more below about positioning your alarm.
  • Your smoke alarm may be damaged or have developed a fault. Exposure to water, fire, grease and certain types of paint can cause a fault to develop. If there is a fault, replace your smoke alarm immediately to protect your home and family.

Smoke alarm chirping intermittently

  • Replace the battery* in your smoke alarm. Ensure you are using the correct battery type and are inserting it the correct way around. If the battery is low, it is more likely to sound at night as a drop in room temperature can impact the battery’s ability to power the alarm.
  • Check the manufacture date on your alarm. Smoke alarms usually last for a maximum of 10 years, so if the manufacturing date is approaching 10 years or more than 10 years, it’s time to get a new smoke alarm. Sensors inside the alarm deteriorate after this time causing the alarm to be less effective.
  • Your smoke alarm may be damaged or have developed a fault. Exposure to water, fire, grease and certain types of paint can cause a fault to develop. If you suspect a fault, replace your smoke alarm immediately to protect your home and family.

How to stop wired alarm chirping intermittently

* All new or recently extended homes should have mains powered, interlinked alarms fitted which also have a back-up battery. Intermittent chirping in mains-powered alarms is often caused by low power in the back-up battery.

Replacement batteries for smoke alarms

Smoke alarms usually require either Alkaline AA batteries, an Alkaline 9V battery or a Lithium 9V battery. Buy replacement smoke alarm batteries as soon as possible to ensure that your family would be alerted to a fire in your home.

Mains powered smoke alarm need replacing?

Whether your smoke alarms are mains powered or battery powered, they should be replaced after 10 years due to a deterioration of the sensors. Battery alarms are easily changed and installed, but how do you replace a mains powered alarm? Most mains powered alarms can be replaced without the need for an electrician if you purchase the exact same model, if still available, or an Easichange® replacement where applicable.

Discontinued smoke alarm need replacing?

If you need to purchase a replacement alarm, but find that your existing model has been discontinued, we have a dedicated collection of replacement smoke and heat alarms. This range consists of models specifically chosen to be the simplest, most direct replacement alarms that can often be installed without the need for an electrician.

Related help guides:

Preventing false alarms

The type of sensor an alarm has determines where it should be positioned in the home. False alarms may be due to the wrong alarm type being used in or near a steamy, dusty or smoky environment.

  • Heat alarms are more suited to areas such as the kitchen or garage that are often smoky or dusty. Other types of sensors would be prone to false alarms in these areas.
  • Optical smoke alarms are ideal for bedrooms, living rooms and ground floor hallways.

To avoid causing false alarms or affecting the performance of an alarm, it is good practice to avoid installing alarms in the following locations:

  • Next to a door, window, air vent or fan that would create a draft
  • Outside
  • Anywhere that airflow would be obstructed by curtains or furniture
  • Locations that are steamy or humid such as a shower room

Find out more about positioning your smoke alarm in your home or take a look at our help guides for more information about types of alarm sensor.

Always ensure you act as quickly as possible to change or replace a defective smoke alarm to keep your home and family safe. If you require any further assistance, contact our customer service team on 0800 612 6537 or email support@safelincs.co.uk.

Frequently Asked Questions (FAQs)

Why is the smoke alarm beeping three times?

When your smoke alarm is beeping three times in succession, this typically indicates a specific message from the manufacturer. The smoke alarm beeping three times often signifies smoke detection – this is different from the single chirp pattern of a low battery warning. Some models use a pattern of three beeps followed by a pause, repeating this sequence to indicate the presence of smoke particles. This could be triggered by actual smoke, dust in the sensing chamber, steam or cooking fumes. If there’s no obvious smoke source, try cleaning the unit by gently vacuuming the exterior vents. In some newer models, a smoke alarm beeping three times can indicate a fault with the sensor itself. If cleaning doesn’t resolve the issue and you’ve verified there’s no fire, check your alarm’s user manual for specific beep pattern meanings or consider replacing the unit.

Why is the hardwired smoke detector chirping?

Your hardwired smoke detector chirping typically signals a specific issue that needs attention. Despite being connected to your home’s electrical system, most hardwired smoke detector units have backup batteries that require periodic replacement. The hardwired smoke detector chirping often indicates that this backup battery is low. Other potential causes include dust accumulation in the sensing chamber, power surges affecting the electronic components, loose wiring connections, or the unit reaching the end of its service life (typically 10 years). To troubleshoot, replace the backup battery first, then try resetting the alarm by disconnecting it from power and removing the battery for 30 seconds. If your hardwired smoke detector chirping continues, check for dust and clean the unit. For persistent issues, the age of the detector or wiring problems may require professional assessment.

Why is my mains powered smoke alarm beeping?

Your mains powered smoke alarm beeping is typically caused by one of several issues. Most mains powered smoke alarms have backup batteries that need replacing periodically, and a low backup battery is the most common reason for beeping. Even though your smoke alarm is connected to mains power, the backup battery ensures protection during power outages. Other causes include dust accumulation on the sensing chamber, end-of-life warnings (smoke alarms typically last 10 years), or a fault in the alarm itself. Try replacing the backup battery first, then clean the unit with a vacuum or hairdryer on a cool setting to remove dust. If your mains powered smoke alarm continues beeping after these steps, check the replacement date on the back – it may simply be time for a new unit.

Why is the smoke alarm beeping every 30 seconds?

When your smoke alarm is beeping every 30 seconds, this is almost always an indication of a low battery. This specific timing pattern is programmed by manufacturers as a low battery warning. The smoke alarm beeping every 30 seconds is designed to be annoying enough to prompt action but not so frequent that it’s confused with an actual fire alarm. Replace the battery as soon as possible using the correct type (usually 9V or AA, depending on your model). If the smoke alarm beeping every 30 seconds continues after battery replacement, the unit may have reached the end of its life (typically 10 years) or developed a fault. Check the manufacture date on the back of the alarm to determine if replacement is necessary.

Why is the smoke alarm beeping intermittently?

Your smoke alarm beeping intermittently can be caused by several factors. The most common reason for a smoke alarm beeping intermittently is a low battery that needs replacement. Other causes include dust or insects inside the sensing chamber, humidity fluctuations, temperature changes or the unit reaching the end of its service life. Clean your smoke alarm by gently vacuuming around the exterior vents to remove dust. Ambient conditions can also trigger intermittent beeping – smoke alarms are sensitive to rapid temperature changes or high humidity. If your smoke alarm beeping intermittently persists after battery replacement and cleaning, check the manufacture date – smoke alarms generally need replacement after 10 years, even if they appear to be working.

Why is the smoke alarm beeping without a battery?

When you experience a smoke alarm beeping without a battery, there are several possible explanations. For mains-powered units, the alarm can still beep without a backup battery installed because it’s drawing power from your home’s electrical system. The beeping may be a warning that the backup battery is missing and needs to be installed. For battery-only models, a smoke alarm beeping without a battery might actually be residual power in the capacitor that can cause chirping for a short time after battery removal. Another possibility is that you’re hearing beeping from a different alarm in your property. Try listening carefully to locate the exact source. If your smoke alarm beeping without a battery continues for more than a few minutes, check all other alarms in your home, including carbon monoxide detectors.

Why is the smoke alarm beeping with a new battery?

If your smoke alarm is beeping with a new battery, several issues might be causing the problem. First, ensure the new battery is properly seated in the compartment and is the correct type for your model. Sometimes, a smoke alarm beeping with a new battery occurs because the battery terminals aren’t making proper contact – try cleaning the contact points with a dry cloth. Another common reason is that the battery might be old despite being ‘new’ to your alarm – check the expiry date on the battery. Dust and debris in the sensing chamber can also trigger beeping even with a new battery installed. Finally, if your smoke alarm beeping with a new battery persists, check the unit’s age – smoke alarms have a service life of approximately 10 years, after which they should be replaced regardless of battery condition.

Why is the smoke alarm beeping after changing the battery?

When your smoke alarm is beeping after changing the battery, it can be frustrating but is usually solvable. The most common reason for a smoke alarm beeping after changing the battery is improper installation – check that the battery is correctly seated and the right type for your model. The battery compartment may not be fully closed, or the alarm might not be properly reattached to its mounting bracket. Some smoke alarms require a reset after battery replacement – look for a test/reset button to press and hold for about 15-20 seconds. Dust accumulated in the sensing chamber can also cause beeping to continue. If your smoke alarm beeping after changing the battery persists, verify the age of the unit – smoke alarms older than 10 years need replacement as the sensors degrade over time, regardless of battery condition.

Why is the smoke alarm beeping after removing the battery?

If you’re experiencing a smoke alarm beeping after removing the battery, this can be puzzling, but it has several explanations. Many smoke alarms contain capacitors that store a small amount of power, which can cause the smoke alarm to beep after removing the battery for a short period – usually up to 15-20 minutes. For hardwired models, the alarm continues to receive power from your home’s electrical system even with the backup battery removed. Some interconnected systems will continue beeping if any alarm in the network has a low battery or fault. Try waiting 20 minutes after battery removal to see if the beeping stops naturally. If your smoke alarm beeping after removing the battery continues beyond this time, check if it’s a mains powered unit or if another alarm might be causing the noise.

Why is the smoke alarm beeping every few minutes?

When your smoke alarm is beeping every few minutes, this typically indicates a specific issue that needs addressing. The pattern of the smoke alarm beeping every few minutes (rather than continuous sounding) usually points to a maintenance alert rather than a fire detection. The most common cause is a low battery that needs replacement. Other possibilities include dust accumulation in the sensing chamber, a fault in the electronic components or an end-of-life warning. Smoke alarms are designed to last approximately 10 years before requiring replacement. If your smoke alarm beeping every few minutes continues after installing a fresh battery and cleaning the unit, check the manufacture date on the back. For models approaching or exceeding 10 years of age, replacement is the best solution, as internal sensors degrade over time.

Why is smoke alarm beeping randomly in the middle of the night?

Your smoke alarm beeping randomly in the middle of the night is a common and frustrating issue. This typically happens because battery power naturally drops at night when temperatures fall. The smoke alarm beeping randomly in the middle of the night is actually the low battery warning becoming more noticeable as the battery power reaches a critical threshold in cooler night time temperatures. Another possibility is that steam or humidity from evening showers might be triggering the alarm if it’s located near bathrooms. Insects can also be more active at night and may enter the sensing chamber. To resolve night time beeping, replace the battery immediately, clean the unit thoroughly, and consider relocating alarms that are too close to bathrooms or kitchens. If the issue persists, check the age of your alarm – units older than 10 years should be replaced.

How do you stop a smoke detector from chirping without a battery?

To stop the smoke detector from chirping without a battery, you’ll need to follow specific steps depending on the type of unit you have. For battery-only models that are chirping without a battery installed, the issue may be residual power in the capacitor. To stop the smoke detector from chirping without a battery in this case, press and hold the test button for 15-20 seconds to discharge any remaining power. For hardwired models, even with the backup battery removed, they’re still connected to your home’s electrical system. You’ll need to turn off power to the circuit at your breaker box, then press and hold the test button to discharge the remaining energy. Some hardwired systems may require a reset procedure – disconnect the unit from the mounting bracket for 15 minutes, then reattach it. If chirping continues, the issue might be with another interconnected alarm in your system that needs attention.

Why is the smoke alarm beeping, but there is no smoke?

When your smoke alarm is beeping, but there is no smoke, several non-emergency factors could be triggering the alarm. The most common reasons for a smoke alarm beeping but no smoke include dust or insects in the sensing chamber, steam or high humidity, rapid temperature changes or cooking fumes that have reached the alarm. Clean your smoke alarm by gently vacuuming the exterior vents or using a hairdryer on a cool setting to blow out dust particles. Consider the location of your alarm – units placed too close to bathrooms or kitchens are prone to false alarms. Some alarms are more sensitive than others; optical alarms are better for living spaces, while heat alarms are more suitable for kitchens. If your smoke alarm continues to beep after cleaning, even though there is no smoke, check the age of the unit. Sensors deteriorate over time, and alarms older than 10 years should be replaced.

Why is the smoke detector beeping with a new battery?

If your smoke detector is beeping with a new battery, there are several potential issues to troubleshoot. First, ensure the smoke detector beeping with the new battery isn’t due to improper installation – check that the battery is correctly seated and the correct type for your model. Some smoke detectors require specific battery brands or types to function properly. The ‘new’ battery might actually be old or expired – check the expiration date. Dust and debris in the sensing chamber can also cause persistent beeping despite a fresh battery. Some models require a reset after battery replacement – look for a test/reset button and hold it for 15-20 seconds. If your smoke detector beeping with the new battery continues, check the manufacture date on the unit. Smoke detectors have a limited lifespan of approximately 10 years, after which internal sensors degrade regardless of battery condition.

Why is the smoke alarm chirping?

Your smoke alarm chirping is typically sending a specific alert message that requires attention. The distinctive chirping sound (different from the continuous alarm) usually indicates a maintenance issue rather than fire detection. The most common reason for a smoke alarm chirping is a low battery that needs replacement. Other causes include dust or insects in the sensing chamber, high humidity affecting the electronics or the unit reaching its end of life (typically 10 years). Some models use different chirping patterns to communicate specific issues – consult your user manual to decipher the message. To resolve the smoke alarm chirping, replace the battery with the correct type, clean the unit thoroughly and check the manufacture date. If your smoke alarm is approaching 10 years of age and continues chirping after battery replacement and cleaning, replacement of the entire unit is recommended.

How do you change the smoke alarm battery?

To change the smoke alarm battery effectively, follow these straightforward steps. First, identify what type of battery your alarm uses – typically, 9V or AA batteries are common. To change the smoke alarm battery safely, turn off power to hardwired models at the circuit breaker if applicable. For most models, twist the alarm counterclockwise to detach it from the mounting plate or open the battery compartment directly. Remove the old battery carefully, noting how it’s positioned. Insert the new battery in exactly the same orientation, ensuring it’s properly seated in the compartment. Close the battery door securely or reattach the alarm to its mounting plate by twisting it clockwise until it clicks. Once installed, press the test button to verify the new battery is working properly. For optimal protection, change the smoke alarm battery at least once a year or immediately when you hear the low battery warning chirp. Mark the replacement date on the inside of the battery compartment for reference unless your smoke alarm contains sealed batteries that are not designed to be replaced – in this instance, the product has reached the end of its life and should be replaced.

Mel Saunders

Head of Marketing

With over 20 years of experience in content writing, design and marketing, Mel now heads up the Content & Marketing Team at Safelincs. Having been in the fire safety industry for over 5 years, Mel has now developed a deep understanding of some of the critical issues facing the industry. Alongside her team, she aims to support the public with resources and information to help them improve fire safety at home, in the workplace or in 3rd sector organisations.

Latest Posts by Mel Saunders

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