Don't ignore the cold facts about keeping warm this winter

For years, many British households have been a soft touch for plumbers who won't touch a spanner for less than 100. The AA's Home Emergency Response service hopes to change all that and it has already made some big promises.

The company's blurb says: "With one phone call, a skilled and AA-approved tradesman will be sent to your rescue – no matter what time of day or night, 365 days a year."

The AA says that last winter homeowners spent an average 343 tackling emergencies , a figure probably exacerbated by cold weather – and crucially only 20 per cent of claims were covered by an existing insurance policy.

The idea of having to go days waiting for a boiler to be repaired has caused a boom in the home emergency market. British Gas has sold more than 7.5 million policies, ranging from central heating cover (4.6 million) to plumbing and drains (1.7 million) and electrical (1.4 million), with many homes having multiple policies.

There's no doubt that the demise of the "little man" around the corner – who tackled home emergencies well enough until about 1980 – has left many of us at the mercy of big companies which profit handsomely from wonky boilers.

One of the most successful is business whizz-kid Richard Harpin, who spotted the gap to launch Homeserve in 1993.

This week, he pocketed 66m by selling a third of his shares in the company – while retaining further shares worth about 170m.

About 2.8 million households are reckoned to hold Homeserve policies and it isn't only the AA which senses rich pickings in the sector.

Supermarket giant Tesco has unveiled a plan to enter the market, with one pilot project already under way, but the real puzzle, given all this furious competition, is that the price of looking after your boiler is still rising.

Price comparison service uSwitch.com says the average cost of boiler cover has surged 20 per cent in a year – from 125 to 142. A year ago, cheapest cover cost just 67 (now 80).

Yet despite that, uSwitch.com reckons boiler cover is still a good-value buy – when it can cost up to 1,200 to replace four key boiler parts. That's the equivalent of paying 142 a year for boiler cover for more than eight years.

However, the December edition of Which? Money magazine says some emergency policies are not all they are cracked up to be.

For example some policies to guard heating systems – offered by AXA, the Co-op, John Lewis and Legal & General – are invalid in warmer weather, from May to August.

It is also vital to check out the limit of an insurer's payout when a boiler needs serious repairs: The Co-op's low premium policy has a limit of 50, while Marks & Spencer's policy (costing 50) has a generous 1,000 limit.

Which? Money says: "A major reason for taking out emergency insurance is the risk of boiler breakdown in the middle of winter.

"But not all boilers qualify for emergency repairs. Many exclude boilers more than 15 years old. Tesco and Prudential have a limit of 10 years, while Legal & General draws the line at just eight."

Several policies do offer unlimited cover on heating systems – including Homeserve, British Gas, Scottish Power and E.ON.

"If you buy the most expensive policy, you should be well-covered," says Ann Robinson of uSwitch.com. "But be aware, boilers usually have to be serviced at least once a year to be covered. This can be difficult without a regular service contract."

Editor of comparison website Energy Choices, Seamour Rathore also points out that most policies don't offer cover for the first 30 days after purchase – to protect companies against claims on systems which are busted before a policy is purchased.

As I found when I renewed a long-standing British Gas Homecare policy, it might also be worth gathering rival quotes to ease negotiations along.

When I quoted one of these figures to British Gas, it came back with a much lower quote on the condition I pay a call-out charge of 50 per time.

If I can keep to two call-outs or fewer in the year, I should end up in pocket – and warm on the darkest winter days.