Installation of a Gas Boiler

Gas boilers are extremely popular in the UK. Whether you’re a homeowner or tenant, an installation of a gas boiler provides convenience and comfort towards your energy bills.

But what exactly is a ‘gas boiler’, and what steps are there in the installation process? Maybe your old boiler has finally kicked the bucket, or you’re playing it smart and avoiding a breakdown. Either way, you’re doing the right thing.

Ready to organise an installation for your home, then you’ll need the answers to these questions.

This article will answer your questions about what you need to think about with an installation of a gas boiler. This ranges from fuel and boiler types, to who can perform the installation as well as all the costs you will need to consider.

For further information on choosing a boiler installer, take a look at one of our other articles:

Boiler Installations in Cardiff

Best Boiler Fitters

Installation of a gas boiler

Without further ado, let’s begin!

Installation of a Gas Boiler – What is a gas boiler?

As a product that’s designed to heat your home, ‘gas boiler’ is actually a very generic term. As you’ll probably work out, this refers to the type of fuel for which there are a few available. So, when you think of an installation of a gas boiler, it could mean a number of things.

But there are other types of fuel besides gas available as well, including LPG (Liquid Petroleum Gas) and Oil.

As a fuel type, natural gas certainly has its advantages. It’s obtained through more environmentally friendly methods and is much cleaner to burn than oil. As well as this, natural gas boasts more financial benefits. The fuel and installation cost will be less, you’ll be able to save hundreds of pounds off your annual energy bills. If you’d like to know more about Oil to LPG conversions, please click here.

Installation of a Gas Boiler – What types of boiler are there?

Installation of a Gas Boiler - what types of boiler are there?

Besides fuel, there are different types of central heating system as well. For instance, a ‘gas boiler’ could refer to any one of these:

Along with a few other options, most central heating systems within the UK will fall under one of these categories.

Installation of a Gas Boiler – Combi Boiler

Combi Boiler?, Simply short for ‘combination boiler’ and they tend to be more compact than the other options. A big benefit for combi boilers is that they don’t need a cold water storage tank or a hot water cylinder.

Water comes from the mains supply into the boiler, which will only heat the water if you want it. In other words, the boiler won’t be wasting any energy because it’ll strictly be working on an ‘as-and-when’ basis.

Installation of a Gas Boiler – Regular Boiler

With regular boilers, you’ll require a cold water storage tank and a hot water cylinder somewhere else in the property. For a while regular boilers were the most popular available, installed in the majority of homes in the UK.

With regular boilers you can take hot water from multiple sources simultaneously without losing pressure. This is because of the storage tank, which allows a steady level of pressure to fall back on.

As a result, regular boilers are often the best choice for larger properties with several bathrooms.

Installation of a Gas Boiler – System Boiler

System boilers are different to open vents, because the heating system is pressurised from the mains between 1 and 1.5.

System boilers can operate with a gravity fed hot water cylinder or a pressurised unvented hot water cylinder. More space is made available in the property, because they don’t require a storage tank.

The installation of a system boiler combined with a pressurised unvented cylinder, is a relatively quicker and a neater process than some other types. They’re also fantastic for places with a high demand for hot water and allow multiple taps to simultaneously provide water.

Because the water supply comes from the mains instead of a tank like with regular boilers that rely on gravity for their water supply, the pressure coming out of the taps will be much higher.

Useful Links

If you’d like to know further details about the process of buying a new boiler, you can also take a look at some of our other posts:

Which? Boiler Installation

What type of boiler will I need?

Oil to LPG

Will a new boiler save me money?

LPG Gas Boiler Installation

Replacing old boiler with combi boiler

When do you need to install a new one?

If there’s any time in the year that’s best to sort out installation of gas boiler, it’s during the summer months when the heating isn’t on as much. Because you’re far less reliant on the heating and hot water during this period, the process can be made much easier without any hassle. However, the installation process is usually completed in two days.

As well as this, the age of your current boiler needs to be considered. Is it an old unit, between 12 to 15 years? If this is the case, it might be worth looking into to getting a new one installed.

Can you install one by yourself?

The number one rule with any installation of a gas boiler, is that only a fully-qualified, Gas Safe Engineer has the authority to safely carry it out.

If you, or anyone you know is performing an installation without the proper qualifications, not only is it a risk to yourself, it is a criminal offence to install any gas appliance if you are not a qualified Gas Safe registered engineer. There would also be potential health and safety risks for people in the surrounding area.

Where do you want your boiler installed?

While it depends largely on what type of boiler you already have in your property, the easiest option for where you want your new one to go is in the same place as your old one before. A popular choice for an installation of gas boiler is either in the kitchen or hidden in your airing cupboard. 

Airing cupboards can be a preferred choice because they are usually sited in the centre of the house. This gives an advantage on hot water delivery alleviating any dead legs [running excessive cold water off before the hot water arrives]. The only downfall is that most airing cupboard installs incur the extra cost of a vertical flue assembly [usually around £300].

As long as everything has been installed correctly and the boiler flue can be properly positioned while adhering to regulations, you can place it almost any room. Seek professional advice from a gas safe registered engineer before siting any gas appliance especially when a flue is involved.

What happens after the installation?

When the works have been completed the installer should produce for you a commissioning certificate (Benchmark) and the installation company will notify building control that you have had the new boiler installed. This will produce a Building Regulation Notification Certificate which you should receive a copy of either via email or in the post. 

An example of a Building Regulations Certificate

Upon the initial survey or quotation, you will have been advised what warranty you will get for the boiler.


Always check when arranging an installation of gas boiler that you have a warranty that you’re comfortable with.  Every installation needs to be up to a certain standard in order to be signed off, but as long as a fully-qualified Gas Safe Engineer is the one that has carried out the procedure, then you shouldn’t have a problem.

A typical warranty certificate

The installer should provide you with a magnetic filter on all new boiler installations. The reason for this is this filter can extract debris from the water flowing through the pipes, this includes non-magnetic and magnetic sludge.

This collects on a magnetic chamber and can be easily accessed to be cleaned annually at service intervals or when required.

This filter will protect the life of the boiler from any debris, without it you could run the risk of that boiler not working as efficiently in years to come. These filters come with various warranties depending on what filter you have fitted, check with the installation company or on your quotation. 

Finally, the installer should leave you with the manual for the boiler containing a service record at the back. Services are carried out annually to maintain the warranty of the boiler. This doesn’t have to be done by your installation company, but can be done by any Gas Safe Registered engineer. 

However, some installation companies may have special offers on an annual service or a service package. So always ask the question as this could save you some money in the long run. 

What we can do for you

Here at B T Morgan Heating Engineers, we fit every boiler with:

a Magnetic filter (with a 20/25 year warranty), EPH Wireless Programmable Room Thermostat (if we do not utilise the existing ones), 7-10 year parts and labour warranties with Viessmann and 10 year warranty on the stainless steel heat exchanger. We chemically flush the system and fit an approved inhibitor with every boiler installation or new central heating system. 

Why not have a look at our other blog, replacing an old boiler with combi boiler. If you’d like to know the best way to get a Boiler Quotation, click here to get a free online quote or contact us and we will be able to assist with all your boiler requirements and queries.