Boiler of the Month: Grant Vortex Pro External

Published: 01 Oct 2025 ・ Read time: 5 Mins

For a high-efficiency condensing boiler designed for outdoor installation, the Grant Vortex Pro External 26kW Oil Combi Boiler with Flue is a superb choice.

Designed with the installer in mind, Grant boilers, particularly their Vortex oil-fired range, are a popular choice for several compelling reasons, especially for off-gas properties. Promoting high efficiency, product versatility, and future-proofing, Grant boilers are renowned for their reliability and reputation and known throughout the trade for their ease of installation as well as long-term maintenance.

At City Plumbing, the home of heating, we continue to offer our expert boiler recommendations, this month focusing the spotlight on the impressiveness of the Grant Vortex Pro External 26kW Oil Combi Boiler.

About the Grant Vortex Pro External 26kw Oil Combination Boiler

The Grant Vortex Pro External 26kW Oil Combination Boiler is a highly efficient, A-rated condensing boiler specifically designed for outdoor installation, making it an excellent space-saving choice for homes not connected to the gas grid.

With a durable, weatherproof casing and built-in frost protection, this 26kW model provides both on-demand mains pressure hot water and central heating. It features Grant’s patented heat exchanger technology for maximum efficiency and comes supplied with a multi-directional flue for simpler installation, making it a reliable and economical heating solution for medium-sized properties.

Key Features and Specifications

This model incorporates Grant's established technology within a robust, weatherproof casing.

Key Features:

External Design: Features a high-quality, powder-coated external casing and is designed with built-in frost protection, allowing it to be reliably installed outdoors in all weather conditions.
High Efficiency: It's a condensing boiler utilising the patented Vortex stainless steel heat exchanger and turbulator baffle system to extract latent heat from the flue gases, leading to higher efficiency.
Combi Boiler: Provides both central heating and mains pressure domestic hot water on demand, eliminating the need for a separate hot water cylinder and feed and expansion tank.
Flue Included: Supplied with a factory-fitted, multi-directional flue to help reduce installation time.
Burner Technology: Equipped with a low NOx Riello RDB compact burner.
System Components: Includes a 24-litre expansion vessel, automatic air vent, pressure relief valve, and a high-efficiency circulating pump.
Ease of Maintenance: Features neon diagnostic indicators and a unique drop-down control panel for easier servicing.
Biofuel Compatible: Suitable for operation on standard kerosene and up to a 30% biofuel blend (B30K).

Key Benefits:

The main benefits of choosing this external combi boiler are centered around space-saving, efficiency, and reliability.

Space & Installation

Saves Internal Space: The primary benefit of the external design is that it frees up valuable internal space (utility room, kitchen, etc) that would otherwise be occupied by the boiler and hot water cylinder.
Quick Installation: The factory-fitted, multi-directional flue and pre-assembled internal components (like the expansion vessel and pump) simplify and speed up the installation process.
Reduced Noise: Being installed outside contributes to exceptionally quiet operation within the home.

Performance & Economy:

High Efficiency: The condensing technology and stainless steel heat exchanger maximise the heat extracted from the fuel, which significantly helps to lower heating and hot water running costs compared to older, non-condensing boilers.
Mains Pressure Hot Water: Delivers a good flow rate of instant hot water at mains pressure, suitable for medium-sized homes with one bathroom.

Durability & Sustainability:

Weatherproof: The robust external casing is designed to protect the boiler's components from the elements, ensuring long-term reliability.
Future-Proofing: Its biofuel compatibility supports the use of up to a 30% biofuel blend, offering a more sustainable heating option for off-gas properties.
Low Emissions: The low NOx Riello burner technology ensures compliance with environmental standards and reduces greenhouse gas emissions.

Buy Boilers at City Plumbing

With its spectacular array of features and benefits alongside the industry renowned name, the Vortex Pro from Grant UK is a top quality choice of boiler for those buildings where space inside is limited.

A competitive-priced solution that promotes high efficiency and excellent hot water performance, both installers and customers can be confident of a powerful performer when choosing a Vortex Pro External.

Help your customers make the switch to a Grant boiler today. Take a look at our City Plumbing website for more information.