Ministers review the 500 litre minimum order, which no law actually requires

The government has agreed to review the 500 litre minimum order that is standard across the heating oil trade, saying it can make people pay for more oil than they need. Its reply to the competition watchdog's study of heating oil, published on 13 October, points out that the rules set no minimum at all.

The real limit is what the meter on each tanker is approved to measure, and some are approved for smaller deliveries. Ministers will look at whether the rules are applied more tightly than they need to be, but have given no date.

A new code of conduct would also make suppliers show their minimum order and explain it. At today's prices the smallest usual order costs upwards of £600 including VAT, a hard sum for some households to find at once.

Smaller fills would ease that, though suppliers usually charge more per litre on small orders, because a tanker trip costs much the same whatever it carries.