3 Main Types of Smoke Detectors (And Which One You Need)

House fires can happen when you least expect them. On average in Australia, more people die each year in residential house fires than from natural hazards like bushfires, floods, and storms combined. Installing smoke alarms can halve the risk of death. You have only minutes to escape once a fire starts.

Here, we explain how the three main types of smoke detectors work and what you should consider before installing them. A smoke alarm might not prevent your house from catching fire, but it can save your life.

Smoke Detector Basics

In Australia, it's a legal requirement that all homes be fitted with working smoke alarms. They must comply with the Australian Standard, be less than 10 years old and be either hardwired or fitted with a 10-year non-removable battery. By January 1, 2027, homes will also need to have interconnected smoke alarms.

Smoke alarms work not by detecting heat, but smoke. Here's some insight into the main detection methods.

Type 1: Ionisation Smoke Detectors

Ionisation smoke alarms use a small amount of radioactive material to ionise the air between 2 electrically charged plates, creating a constant electrical current. When smoke enters its chamber, it disrupts the flow and activates the alarm.

Ionisation smoke detectors have the advantage of activating quickly for fast-flaming fires. But, they are slower to activate for smouldering fires, which is the most common type of house fire. With a smouldering fire and a slower-acting alarm, occupants may suffer from breathing difficulties and reduced visibility while escaping.

This type of alarm is also more prone to false alarms from things like cooking. And because smoke alarm sounds are intentionally shrill and extremely loud, this can lead to the home's occupants disconnecting the battery, rendering them useless in times of an emergency.

Type 2: Photoelectric Smoke Detectors

Authorities now recommend that if you are going to install just one type of smoke alarm that you choose photoelectric smoke alarms. They work by aiming an angled light source into a sensing chamber. When smoke enters the chamber, it reflects the light onto the sensor, triggering the smoke alarm beeps.

Photoelectric smoke alarms are less prone to false alarms from sources like steam, and they sound faster in the presence of a smouldering fire. In doing so, they reduce the risk of smoke inhalation and visibility issues, allowing occupants to escape the home sooner.

Type 3: Dual Sensor Smoke Detectors

Dual sensor smoke alarms contain ionisation and photoelectric technology in one device. These specialised smoke alarms sense smoke from both flaming and smouldering fires, so they are the ideal early warning system to protect your family and your belongings in case of a house fire. (Electrical fires are the most common cause of house fires, and these can smoulder or flame, depending on where they occur and what's around them.) However, because cooking appliances and bathroom steam can trigger false alarms in the ionisation alarm, they are generally not suitable near kitchens or bathrooms.

Dual sensor detectors can also refer to those that combine photoelectric smoke and carbon monoxide gas alarms. This type of detector can also be a life-saving device for homes with gas heating, as it detects dangerous levels of colourless and odourless carbon monoxide in the home, as well as home fires.

Other alarms with dual features work using heat sensors as well as detecting smoke. These can provide additional protection from different types of fires and are ideal for kitchens and laundries.

Smoke Detector Comparison Table

How to Choose the Right Smoke Detector

Smoke alarms are installed to save lives, so it's critical to choose the right type for your home. Fire authorities recommend that if you only have 1 type of smoke alarm installed, it's photoelectric because they are better at detecting dangerous, slower-burning house fires that can make it difficult to escape the home quickly. To check what sort of smoke alarm is installed in your home, check the label. If it's not mentioned, look for a bright yellow radiation symbol that is present on all ionisation alarms.

Battery-operated smoke alarms v hard-wired smoke alarms

Hard-wired smoke alarms connected to your home's electrical system by a licensed electrician are recommended over battery-operated smoke alarms. These powered smoke alarms are more reliable and won't fail as easily if you forget to replace batteries (although you should always check that your hardwired smoke alarm's back-up battery is in good working order).

Are interconnected smoke alarms necessary?

Interconnected smoke alarms are also recommended for all homes because when 1 alarm is triggered, they will all sound, giving occupants as much time as possible to evacuate. Interconnected alarms are available for mains-powered smoke alarms and some battery alarms.

What if someone in my family is a heavy sleeper, deaf or hard of hearing?

You can also get specialised smoke alarms for people who are deaf or hard of hearing. These work with a strobe light and vibrating pad that activate when the smoke alarm sounds. However, these types of specialised smoke alarms may also be suitable for those with multi-level homes, heavy sleepers and people who sleep with doors closed or ceiling fans on, who risk not hearing the smoke alarm fast enough.

Smoke Detector Maintenance & Safety Tips

Now that you have an idea of the right smoke alarm for you, it's time to get a better understanding of how to look after it so that it can do its job of keeping you and your family safe. Smoke alarm maintenance is usually straightforward - you just need to remember to do it regularly.

• Choose a date to maintain your smoke alarms and stick to it each year. It could be someone's birthday, a public holiday or another significant date like April Fools' Day. Owners of rental properties should book smoke alarm checks at the same time they do their own home inspection.
• If you have the manufacturer's instructions for cleaning, follow these. Otherwise, gently wipe over the alarm with a microfibre cloth to remove dust.
• Locate the test button and press and hold until the smoke alarm beeps. If you have interconnected smoke alarms, test each one. If the alarm doesn't sound, check the power source or battery.
• Replace smoke alarms that are more than 10 years old. This is their maximum life expectancy, and they may fail to detect a fire after this time. Where possible, hard-wired and interconnected smoke alarms should be installed. These hardwired smoke alarms can only be installed by a qualified electrician.
• Replace lead or alkaline batteries yearly. Lithium battery alarms last 10 years and are replaced as a whole unit.
• Change the back-up battery in hard-wired smoke alarms each year unless equipped with 10-year lithium batteries.
• Only buy smoke alarms that meet Australian standards and have replacement smoke alarms installed by a licensed electrician.
• Ensure that your home has adequate coverage. Working smoke alarms must be installed on every level of a multi-level home. However, if you don't have smoke alarms installed near sleeping areas, living zones and hallways, you may not be meeting the minimum requirements for the size of your home and will require additional smoke alarms.

Is It Time to Upgrade Your Smoke Detectors?

Smoke alarms should be replaced every 10 years, and if yours aren't mains-powered and interconnected, it's time to upgrade to keep your family, pets and belongings as safe as possible.

At Easther Electrical, we'll arrange your smoke alarm installation so that you can sleep soundly. We'll help you upgrade your home's number 1 safety system, giving you advice on the right amount and types of smoke alarms for the right locations within your Wollongong home. Don't wait for the unthinkable to happen, call us today on (02) 4256 5899.

FAQs

What are the three types of smoke detectors?

The three types of smoke detectors are ionisation, photoelectric and dual alarms that combine both methods of smoke detection.

Do I need both ionisation and photoelectric smoke detectors?

Having both ionisation and photoelectric smoke detectors fitted in your home ensures that both slow-burning and fast-burning fires are detected as soon as possible. However, it's important to ensure they are fitted in the correct location to prevent them from being accidentally triggered.

How do I know which smoke detector I need?

If you only install one type of smoke alarm, always choose photoelectric.