Flue Inspection Hatches fitted in London – Flues In Voids

Recently had a failed gas safety certificate in your property due to having concealed flues? Call us today to arrange fitting a fire rated inspection hatch and receive a new gas safety certificate

Flues In Voids

Flues in voids refer to the pipes or ducts that expel the combustion gases from gas appliances, such as boilers or water heaters when they are installed in locations where the flue cannot be readily seen or accessed. This typically occurs when the appliance is located in areas such as ceilings or walls. Flues in voids can present safety concerns, particularly if they become blocked or damaged, as they may lead to the buildup of carbon monoxide (CO) gas.

To ensure the safe operation of gas appliances with flues in voids, it is essential to adhere to relevant regulations and guidelines. In the UK, Gas Safe Register provides regulations and guidance for gas safety. It is important to have regular inspections and maintenance performed by a qualified Gas Safe registered engineer to identify and address any issues with flues in voids.

One key aspect of maintaining flues in voids is the installation of inspection hatches. These hatches provide access to the flue for visual inspection, cleaning, and maintenance. The size and number of inspection hatches required may vary depending on specific regulations and the type of appliance. 

In 2008 the Health and Safety Executive (HSE) published a safety notice following a death earlier that year. The notice was issued with the intention of increasing public awareness about the potential hazards associated with certain types of flues connected to gas-fired central heating systems. This was particularly relevant to a significant number of flats and apartments built since 2000, where these flues may have been improperly installed or may have deteriorated over time

The information provided is crucial for a wide range of individuals and organisations, including homeowners and tenants living in properties with a gas boiler, landlords (both private and social), managing agents, and various entities within the gas industry such as Gas Safe registered businesses/engineers, gas appliance manufacturer, and gas emergency service providers. It’s also relevant to the construction industry, particularly home builders, service providers, and local authorities especially those in housing departments.

The key issue at hand pertains to changes in industry guidance concerning existing gas central heating systems. Specifically, this involves systems where the flue is hidden within a void and cannot be visually inspected to ensure its safety. The new guidance requires the provision of inspection hatches from the 31st of December, 2012.

The industry guidance related to this Safety Bulletin (Technical Bulletin 008, Gas Safe Register) underwent a revision in April 2013. This revision introduced an alternative to the installation of inspection hatches in certain situations. Instead, a carbon monoxide (CO) void monitoring safety shut-off system can be fitted. This system monitors the void for any presence of CO, a dangerous gas and shuts off the system if detected thereby enhancing the safety of these installations

In situations where boilers are situated away from external walls, it’s more common for flues to be routed through voids in ceilings or walls. During routine service or maintenance of the gas appliance, it can be challenging or even impossible to ascertain whether the flue was correctly installed or if it remains in a satisfactory condition.

A faulty flue, when combined with a malfunctioning boiler can lead to the release of dangerous levels of carbon monoxide (CO) into the living space. CO is a lethal gas that is produced by the incomplete combustion of carbon-based fuels. It inhibits the blood’s ability to transport oxygen to cells, tissues, and organs and can cause death swiftly and without warning.

The revised guidelines likely include updated safety measures and best practices that engineers should follow to ensure the safe installation and maintenance of gas-fired central heating systems. This is particularly important for flues that run through wall or ceiling voids, and for the ongoing maintenance and repair of these systems. As such, homeowners and property managers should always ensure that any work on gas systems is carried out by a Gas Safe registered engineer, who will be up-to-date with the latest safety guidelines.

Why is a flue inspection hatch needed?

A Gas Safe registered engineer will be unable to inspect a room sealed, fan assisted boiler with a flue hidden behind a ceiling or wall if you live in a property (most likely a flat or apartment). 

The flue must be accessible for inspection because it removes fumes from the boiler. A blocked or damaged flue could put occupants at risk of carbon monoxide poisoning (though being unable to access the flue does not automatically imply that it is unsafe). 

If this applies to a property you own or live in, inspection hatches to access the flue should be installed. If a Gas Safe registered engineer visits and is unable to see the flue, the appliance will be classified as ‘At Risk,’ which means it will be turned off (with your permission) and it cannot be used again until inspection hatches are installed in the appropriate locations.

What type of boiler flue inspection hatches do you fit?

It is important to have proper inspection hatches fitted for gas boilers to ensure safe operation and maintenance. Inspection hatches should be located in a readily accessible position such as directly above the boiler, and should be large enough to allow easy access to the inside of the appliance for inspection and maintenance purposes. 

The hatches should be fitted with a suitable latch or lock to prevent unauthorised access and should be made of a material that is fire proof and resistant to corrosion. As required by law we install fire resistant 300mm x 300mm inspection hatches where required and where feasible. In exceptional circumstances and where every due care has been taken to install these hatches, but there are size or structural restrictions, smaller sizes may be considered.

How much will fitting inspection hatches cost?


This varies from property to property and depends on the number required. We install hatches at 300mm x 300mm and positioned within 1.5m to any joint in the flue system or at bends. Some properties will only need one hatch, while others may need a few more.

Our inspection hatch installations start from £130 + VAT per hatch and this decreases in price depending on the number required



What happens once the flue inspection hatches have been fitted?


If required and if agreed in advance we are able to carry out a new gas safety inspection and issue a gas safety certificate for the property.


What other gas boiler related services do you provide?


Carbon Monoxide Detector: 

Installation of mains powered Carbon Monoxide Detectors. A device that monitors and detects Carbon Monoxide leakage from a gas appliance or gas boiler. Whilst not a legal requirement for a modern gas boiler installation, it is an advisable and low cost precautionary measure. Installation of wireless and wired carbon monoxide detectors

Smart Heating Controls:

Smart Heating Controls are intelligent thermostatic controls for your heating system. You can remotely control your heating from a smartphone, tablet, or other internet-connected device that is wirelessly connected to the internet. They also help save  money on your heating bills because you have more control over your heating. Additionally, you have individual room temperature control. By not heating unused spaces, you have more opportunities to reduce your heating costs. Most common smart heating controls include thermostats and TRVs


Heat Detectors:

Installation of wires, mains and interlinked heat detectors where a smoke alarm isn’t suitable. Heat detectors are important equipment for detecting fires and ensuring safety. As the name suggests, the devices sense the temperature of a room or area in order to detect fires. Heat detectors work on a similar principle used by smoke detectors, by tracking the temperature instead of smoke.

Smoke Alarm: 

Installation of mains wired and interlinked smoke alarms, for homes, apartments, HMOs and businesses. Smoke alarms are a legal requirement for rental properties but a must have for all homes and businesses to protect lives


Boiler Servicing: 

An annual boiler service is carrying out a series of checks and cleaning to the boiler in order to maintain and increase the life of a boiler. It is also a requirement by the manufacturer to honour any boiler guarantees. 


Gas Appliance Installation:

Installing and servicing a variety of water heating and cooking appliances. Including pipework and all associated works 


Gas Leak Repair:

Locating and repairing gas leaks from your gas pipework or gas appliances.


Boiler Installation:

We provide a variety of Gas Boiler installations including Heat Only, System Boilers and Combi Boilers. We are experienced and registered installers of all major brands such as Idea, Baxi, Main, Vaillant, Keston and many more.

Frequently Asked Questions


How do I know if my flue inspection hatch is the correct size?


The correct size could be determined by consulting with a  gas safe registered engineer, but as a guide it should allow enough access to an engineer to be able to visually inspect and also test using a gas flue analyser.


Can I install a flue inspection hatch myself?


It is not recommended that you install a flue inspection hatch yourself and recommended a gas safe registered business is employed to ensure the hatches are installed to the correct standards and at the correct locations.



What material should flue inspection hatches be made of?


Flue inspection hatches should be made of a material that is resistant to heat and corrosion such as stainless steel or high temperature plastic. Flue inspection hatches should also be fire rated as to not reduce the fire rating of a property.

How do I know if my flue inspection hatch is properly sealed?

To see if a flue inspection hatch is properly sealed, open and close it several times to ensure that it is secure. You should also look for any visible gaps or cracks around the hatch’s edges.

Can I paint my flue inspection hatch?

You should not paint your flue inspection hatch because it may interfere with its ability to function properly and safely.

Who is responsible for ensuring that flue inspection hatches are properly  maintained?

The property owner is responsible to ensure gas boiler flue inspection hatches are properly maintained

Can I use a flue inspection hatch to check the condition of my gas boiler flue?

To check the condition of the gas boiler flue, a flue inspection hatch can be used, but it is important to follow the manufacturer’s guidelines and have the work done by a gas safe registered engineer to ensure that it is done safely and to the required standards.

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