Oil and LPG boilers

1 How they differ from mains gas

Vaillant says an LPG boiler works the same as a mains gas boiler, the difference being stored fuel, topped up by a supplier¹. Worcester Bosch makes a similar point, adding that LPG can be kept in a permanent tank or small portable cylinders⁷. Oil is likewise delivered and stored, and Worcester notes some oil boilers can go outside the home⁸.

Both come in the familiar forms, with a combi, system or regular layout, and modern versions are condensing boilers²¹. Vaillant says the condensing rule came to new oil boilers on 1 April 2007⁹.

2 Who may work on each

LPG is gas work. Vaillant says servicing must be by a Gas Safe registered engineer¹, and Worcester points out there are more of those than OFTEC engineers⁷.

Oil is different. In Northern Ireland, nidirect says always to use an OFTEC registered technician to install or repair an oil boiler, have it serviced annually and check the ID card³. OFTEC is a trade body that runs registration across the UK and Ireland, including competent person schemes for England and Wales¹⁰. HSE adds that oil appliances should be serviced by a competent person with the chimney regularly swept¹¹.

One older Worcester oil guide describes a lockout reset behind the boiler's front cover¹². That applies only to that oil range and is not repeated here. Worcester's gas manuals say the opposite about the case, so ask your oil engineer what your own boiler allows.

3 Fuel smell and fumes

For LPG, treat a smell as a gas emergency and follow gas smell; Worcester says LPG users call the number on the tank¹³. For oil fumes or leaks, Worcester's Heatslave guide lists extinguishing naked flames, opening windows and doors, switching off the boiler's electricity, isolating the fuel supply and contacting the installer or engineer¹⁴. If a carbon monoxide alarm sounds on any fuel, get everyone outside first and see carbon monoxide.

4 Tanks and paying for fuel

nidirect's oil tank advice for Northern Ireland is to inspect monthly, supervise deliveries, and check insurance covers clean-up; a bund is a legal requirement there for domestic tanks over 3,500 litres¹⁵. Rules elsewhere were not read for this entry, so ask an OFTEC technician.

Ofgem lists heating oil as outside its price cap⁵, and Vaillant says the same of LPG, with suppliers free to set prices and often wanting payment in advance¹. In England and Wales the Boiler Upgrade Scheme adds £1,500 to the air or ground source heat pump grant, making £9,000, until 31 March 2027 for eligible homes heated by oil or LPG with no mains gas⁶.

5 Efficiency rules for oil

England's minimums for oil in an existing home are 91% ErP for a regular boiler and 86% SEDBUK 2009 for a combi, with lower figures in exceptional circumstances¹⁶. Northern Ireland sets 88% SEDBUK 2009 for oil generally and 86% for oil combis¹⁷.