Oil Condensing Boilers

The name ‘Grant’ has in recent years become synonymous with highly efficient oil-fired central heating appliances throughout the UK and Ireland. Designs like the ‘Multi Pass’ boiler achieved efficiency levels far in excess of any UK or European Standards and have helped thousands of homes to reduce their annual fuel bills. So it will come as no surprise to see Grant yet again leading the way with the Grant Vortex oil-fired condensing boiler range with exceptional SAP2009 efficiencies up to 93.3% gross (97% gross for SAP2005).

Grant’s ultra high efficiency Vortex Condensing Range has been on the market for over 10 years and now features 39 different model variations, with outputs ranging from 12-70kW (50,000 240,000 Btu/h).

What is a condensing oil boiler?

Condensing boilers differ from traditional boilers in that they are designed to capture heat normally lost through the flue system during the combustion process. Unlike traditional oil-fired boilers the Grant Vortex condensing boiler has a built-in stainless steel heat exchanger incorporating Grant’s unique turbulator baffle system, which cools the gases to a point where the latent heat, normally lost to the atmosphere through the flue, can be usefully extracted. The additional energy recovered enables the boiler to operate continuously at much higher efficiency levels, resulting in lower heating and hot water running costs.

Easy to commission, service and maintain

As with all oil-fired appliances, Grant Vortex Condensing Oil Boilers require commissioning at the time of installation.
This simple process ensures that the boiler is working at peak efficiency which, in turn, will result in lower running costs and long term reliability. Annual maintenance is also made easy by Grant’s cleverly designed front service access to both the burner and all the internal serviceable parts. This feature enables Grant Vortex Condensing Boilers to be fitted neatly and unobtrusively within either the kitchen or utility room environment. Alternatively, if internal siting is a problem, space-saving outdoor versions are available.


Condensing oil boilers operate at extremely high efficiency levels, producing cool flue gas temperatures, resulting in a ‘plume’ of vapour being visible at the flue terminal. This plume (steam) is a normal condition of condensing boiler operation and indicates that the appliance is working efficiently. As an alternative to a low level balanced flue kit, high level, or vertical kits are available, which moves the plume to a higher level.


Installation must comply with the current British Standards and The Building Regulations. Comprehensive technical information can be found in the installation manual, supplied with every boiler. All burners are supplied factory set at the stated output for use on standard grade Kerosene – Class C2. Grant Vortex Condensing Boilers are not suitable for use with Class D gas oil. Don’t forget to install a Grant Vortex Mag-One magnetic central heating filter –  click here for more details.


The unique heat exchanger on Grant Vortex Condensing Boilers is covered by a 5-year guarantee. All other component parts of the boiler are guaranteed for 2 years from the date of purchase (excluding consumable items), subject to being installed in accordance with the manufacturer’s instructions. On completion of the installation all Grant Vortex Condensing Boilers must be commissioned and registered online by completing the guarantee form located within the Homeowner Zone.