What is a Fire Door Retainer?

Smoke is the main killer in any fire. Fire doors are designed to limit the spread of smoke and fire. In the event of a fire, the fire doors act as protection for rooms and areas, stopping the spread of smoke and fire in a building. This helps in the evacuation process.

Fire doors are specially designed and tested to withstand a fire over 30, 60 and 90 minute timeframes. They are fitted to high standards, which include specified fire door hinges, instrumincent fire seals, and spring door closers. The fire spring door closer, allowing the fire door to automatically spring to a closed position, and not left in an open position.

When a fire door is left open, a fire can travel very quickly, aiding the smoke and fire with fatal consequences. An open fire door helps to ventilate smoke around a building, hindering the escape plan, whilst engulfing a building at a much quicker rate.

When a building is occupied, whether in the public or private sector, often people are unaware of the importance of keeping a fire door closed and these doors are wedged open with all kinds of objects. Door wedges, bricks, cardboard, chairs and even fire extinguishers!

To overcome this problem, fire door retainers, often referred to as fire door hold open devices or fire door guards are installed. When a fire alarm is activated, these devices will release a fire door automatically, under the pressure of a spring fire door closer.

Fire door retainers are typically used in care homes, schools, colleges, universities, hotels, restaurants, public buildings such as offices, libraries, police stations and council buildings. As well as a safety feature of automatically closing the door, they also help with ventilation, free flowing traffic and assist with germ control with less door handle contact.

  • Closes fire door
  • Helps with ventilation
  • Germ control from less door contact
  • Free flowing traffic through busy buildings

There are a few options as to the best way to keep your fire door open safely and legally.

Hardwired fire door retainers: Hardwired into the fire alarm panel. When the fire alarm is activated, the magnets are triggered and released. Simple magnet on the back of the door, connecting to a metal plate on the wall or floor.

Free swing fire door retainers: Hardwired freeswings close the fire door and also take the weight off the door. Allowing the fire door to “swing free”.

Acoustic fire door retainers, also known as  battery operated fire door retainers and fire door guards, uses “listening technology” to pick up the fire alarm sound. This means no expensive cable and labour costs. These devices have increased the use of legally used held open devices on fire doors and decreased the use of fire door wedges.

How do acoustic fire door retainers work?

Acoustic fire door retainers are wirefree, they act as a door wedge, but release to the fire alarm sound, closing the fire door. They have a built-in microphone which listens every few seconds until it identifies the fire alarm sound.

Older versions of these devices are often closed to all kinds of different noises like vacuum cleaners, people talking/shouting or music. This led to dangerous door closing events on people walking through fire doors.

The technology has vastly improved in recent years. New products in the market are now deemed as “smart”, these devices can determine different types of sounds and react specifically to the actual fire alarm.

One such product is Shuttle, a “smart” fire door retainer and has the ability to detect background noises that are not a fire alarm. This means the Shuttle will hold open the fire door and only close to the fire alarm sound.


Shuttle Fire Door Retainer Product Preview



  • Listens and learns fire alarm sound: Learns the sound of the fire alarm in 30 seconds. This mode means the Shuttle will only close to the fire alarm 100%.
  • Works with all fire alarm sounds: including voice, intermittent, continuous, fire alarms, smoke and heat detectors.
  • Quick set up: Just screw Shuttle to the fire door, insert batteries and press a button to activate. No need to teach Shuttle the fire alarm sound. Ignores 95% of sounds including vacuum cleaners.
  • Upto 4 years battery life
  • Holds the fire door open at any angle

See how a Shuttle closes the fire door to a voice fire alarm:

The Shuttle fire door retainer, available at www.sonicco.com

Battery power: Typically, battery operated door retainers use a C size battery. These can be purchased at any shop/supermarket. Shuttle battery power is upto 4 years. This is dependent on the quality of battery used and the usage of the Shuttle.


Acoustic fire door retainers do need maintaining. They have a rubber foot often referred to as a ferrule. These can easily be changed and are readily available through Sonicco.com and fit all battery operated fire door retainers.

Floor plates are used to secure the acoustic door stop in place. These are useful for heavy fire doors or where users have difficulty in knowing how to release the product manually. Often, users will drag the door. The floor plate will stop this, and force the user to release properly..

Fire door stickers are useful for usage of the Shuttle fire door retainer or any other battery operated fire door retainer, instructing how to manually release and also show the manufacturers contact number.

How to fit an acoustic fire door retainer.

Products come with instructions but sometimes these can get lost. Simply go to the Sonicco website for more online downloads.



Fire door retainers have to comply with safety regulations. This includes product standards, fire door integrity tests as well as a fire risk assessment to accompany the installations. It is important that the product has fail safes. For example, should the battery drain, the product will be released, the user will not be able to use it again, until the new batteries are inserted. Should the acoustic fire door retainer fail in any way, again the product must fail to a safe position, i.e. closed. Other factors that are taken into account are activation cycles, how many times can the products operate, in the test the Shuttle must complete 50,000 cycles. Shuttle has features that alert the user to product failings and battery drainage. In the UK the standard is UKCA.