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A boiler must be installed by or under supervision of a qualified Gas Safe engineer and comply with building regulations and the manufacturer's instructions. Unfortunately, the gas industry has seen a surge in newly qualified Gas Safe engineers who have taken short intensive courses to become Gas Safe and as such are not fully competent in the field. Time and time again, we find new installations that have not been installed to manufacturer's specifications and do not fully comply with the building regulations. Incorrect installations may also invalidate the appliance's warranty.

London Heating Expert prides itself to have come about from an academic background and serves to uphold the highest standard in the industry. We follow the regulations closely and make sure your installation is safe to operate.

Drilling a New Opening for the Flue
Gas Tightness Testing
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Wiring in the room thermostat
Lining Up the New Boiler Template against the existing flue opening
Flue Gas Analysis






When installing a new boiler or replacing an old one, it is important to size the boiler correctly. It is essential that the chosen boiler is capable of providing heating based on the heat loss and therefore heat requirements of each dwelling.


In particular, the flow rate of hot water in combination boilers and the rate of heat recovery in stored hot water cylinders need attention.

To ensure the incoming gas pressure to the boiler is sufficient and that it will burn without producing carbon monoxide it is imperative that the gas operator checks for correct gas pipe sizing. When upsizing a boiler, it may also be necessary to run a new line of gas pipework of the correct size to ensure of the boiler's safe operation. Undersized gas pipes cause a gas pressure drop across the pipework due to frictional resistances against the flow of gas, potentially resulting in an incomplete combustion and the production of poisonous and deadly carbon monoxide.

The correct installation of the flue also plays an important role in the safe operation of the appliance.


Boiler flue systems have many restrictions in terms of their maximum length and positioning within the building, as specified by the building regulations. Incorrectly positioned flues may bring the products of combustion back into the house and pose a danger to the residents and/or neighbours.

Inadequately supported flues may come loose and cause the products of combustion and fresh air to mix together.


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Climate Change & Colder Winters


With the latest impacts of the climate change and falling temperatures during winter across the UK, frost is more than ever affecting external pipework. This includes the condensate pipe from condensing boilers running to outside drains .


In the recent years, there's been a surge in reported boiler failures during freezing conditions, the majority of which have come about due to lack of insulation on the condensate pipes causing the condensate to freeze up and block condensate drainage.

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Guidelines & Regulations


There is now tighter guidelines for running and insulating condensate pipes externally. Complying with these standards adds to the cost of your installation, but goes a long way to prevent system failure during freezing conditions, when heating requirements are at their peak.

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Boiler Installation & Replacement Requires Two-man Handling


As such the labour costs will be higher than that of an individual's workmanship. This is not only required by the Health and Safety Executive to protect the installer, but also helps prevent damage to your new appliance during installation.



Where a boiler is being replaced and positioned in the same location, it is usually possible to use the same pipework and flue opening with slight alterations. That is why the job is fairly predictable and therefore it is possible to set a fixed fee for the labour. We have a number of combi boiler packages for you to choose from, and you may qualify to have them installed with our financing options. Please see Financed Packs.


Changing the boiler position or carrying out a new install, on the other hand, requires new pipework installation and provisions for a new flue opening.

System conversions from hot water cylinders to combination boilers also entail extensive system changes. Running new pipelines across the property can on occasions be very challenging and somewhat destructive to the fabric of the house.

These installations will be quoted on a case by case basis.


The installation of a new boiler should be accompanied by power flushing the central heating system to get rid of the dirt and sludge in the system. This is required by most boiler manufacturers to validate the warranty of the new boiler. The addition of a magnetic filter, where none is installed, is also a great way to protect the new boiler and manufacturers are often happy to offer extended parts and labour warranty of up to 10 years for the new appliance where their nominated filter is installed. Since 2023, Part L of the Building Regulations requires an inline magnetic filter to be installed on all systems.

To get a quote for your boiler installation, please book your Job Quotation Survey now.

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