Installing A Boiler Outside: Pros And Cons

Reclaiming precious indoor space is a top priority for many UK property owners, especially in compact apartments or older cottages where every square inch counts. One increasingly popular solution for modernising a home’s layout is installing a boiler outside. 

While traditionally most central heating units are tucked away in kitchens or airing cupboards, moving the appliance to an external wall or a dedicated outdoor enclosure can transform your interior living space. 

However, an outdoor installation isn’t as simple as just moving the unit; it requires specific weatherproofed equipment, adherence to strict Gas Safe regulations, and careful consideration of the British climate to ensure your heating remains efficient when the frost hits.

What Are The Benefits Of Installing A Boiler Outside?

The primary benefits of installing a boiler outside revolve around space-saving and noise reduction within the home. 

By moving the heat source to an external location, you effectively remove the hum of the circulating pump and the whirring of the fan from your living areas, which is a major advantage for open-plan houses or those with bedrooms near the utility space. Additionally, an external setup allows for:

• Interior Design Freedom: You can remove bulky cupboards in the kitchen or hallway, allowing for a cleaner aesthetic or more storage.
• Easier Maintenance Access: Engineers can often service the unit without needing to enter the main living quarters, which is highly convenient for busy households or rental properties.
• Reduced Safety Concerns: While modern indoor boilers are incredibly safe, moving the combustion process outside the building’s envelope provides an extra layer of peace of mind regarding gas leaks or carbon monoxide.

What Are The Drawbacks Of An External Boiler Setup?

The drawbacks of an external boiler setup typically involve higher initial costs and potential efficiency losses. Because the appliance is exposed to the elements, you must invest in a high-quality weatherproofed model or a bespoke insulated cabinet, which can be more expensive than a standard indoor unit. Other drawbacks include:

• Heat Loss: Even with high levels of insulation, heat can be lost as water travels from the outdoor unit through the external walls and into the house.
• Vulnerability: Outdoor units are more susceptible to the long-term effects of corrosion and may be more vulnerable to tampering or theft if not properly secured.
• Condensate Freezing: The condensate pipe, which carries waste liquid away, is at a much higher risk of freezing in an outdoor setup, which can cause the boiler to “lock out” during the coldest nights of the year.

Can Any Standard Boiler Be Installed Outdoors?

You cannot simply take a standard indoor unit and mount it on an external wall; installing a boiler outside requires a model specifically designed with a weatherproof casing. These “external” versions of popular combi or system boilers are built to withstand rain, wind, and varying temperatures without the internal electronics or the burner becoming damaged.

If you were to install a regular indoor boiler outside without a bespoke, manufacturer-approved cabinet, you would not only void the warranty but also create a significant safety hazard. 

Furthermore, external units must be fitted with advanced frost protection sensors to ensure the water within the heat exchanger does not freeze and crack the pipework during a cold UK winter.

What Regulations Govern External Boiler Installations?

The regulations govern external boiler installations through a combination of Building Regulations Part J and Gas Safe standards. Specifically, the flue terminal must be positioned in a way that prevents exhaust gases from re-entering the property or causing a nuisance to neighbours. For an outdoor unit, the flue must be at least 300mm away from any opening window or door. 

Additionally, if you are installing an external oil boiler, there are strict rules regarding the distance from boundaries and the type of base the unit sits on to prevent environmental contamination. All external gas work must be commissioned by a qualified professional who can issue a Building Regulations Compliance Certificate upon completion.

Need A New Boiler Quote?

Thinking about freeing up that kitchen cupboard or clearing out the airing cupboard? Our team is ready to help you find the perfect heating solution that fits your lifestyle and your property’s unique layout.

Request a new boiler quote from Boilers 2 Go to compare high-performance external models from the UK’s leading manufacturers. We provide transparent, fixed-price estimates that include all the necessary weatherproofing, flue components, and frost protection needed for a successful outdoor installation. 

Whether you are a landlord or a homeowner, we make the process of upgrading your boiler simple, safe, and stress-free.

Frequently Asked Questions

Do I need planning permission for an external boiler?

In most cases, you do not need planning permission as it falls under “Permitted Development.” However, if your property is a Listed Building or located within a Conservation Area, you must check with your local planning authority, as the addition of an external unit or a visible flue may be restricted.

How do I protect an outdoor boiler from freezing?

Most dedicated external boilers come with built-in frost protection that fires the burner if the internal water temperature drops below a certain level (usually 5°C). Additionally, your engineer must ensure that all external pipework is heavily lagged with weatherproof insulation to prevent the “beast from the east” from causing a pipe burst.

Can an external boiler be wall-mounted?

Yes, many modern external gas boilers are designed to be wall-mounted on the outside of your property. This is a great way to keep the unit off the ground and away from potential dampness or garden debris. For heavier oil boilers, a solid concrete plinth is usually required.

What is an “external boiler house”?

An external boiler house is a small, purpose-built structure (often made of brick or timber) designed to shelter a standard boiler. While this allows you to use a slightly cheaper indoor model, the structure itself must be built to strict ventilation and fire-safety standards to be legal.

Is it harder to service a boiler that is outside?

Actually, many engineers prefer it! Being outside often means they have more room to work and better light than they would in a cramped kitchen cupboard. However, they may be less keen to visit during a rainstorm, so having a small shelter or “lean-to” over the unit can be a thoughtful addition.