NPOWER will launch a new energy tariff on Wednesday offering free boiler cover and protection against rising prices but you could get cheaper elsewhere.

Npower One has a price-protection guarantee until the end of July 2009 and will include cover for your boiler for one year.

However, customers will have to pay a 5% premium on top of the supplier’s standard deal, one of the most expensive available.

Npower, whose salesmen were last week exposed by The Sunday Times for lying to consumers, has a standard deal at around £1,056 a year for dual-fuel customers. With 5% on top, a customer would pay an extra £53 – a total of £1,109.

It is £314 more expensive than the firm’s cheapest deal Sign Online 10, which costs around £795 a year for dual fuel.

You could choose the cheaper deal and take out boiler cover from British Gas for a year for £156. The total annual bill would be £951– a £158 saving from the Npower One tariff. If you want a capped tariff however, the Npower deal is better value.

The cheapest capped deal is offered by Eon, which fixes rates until October 2009 for an average of £988 a year, although with British Gas’s boiler cover on top you would pay £1,144. You do, however, get two more months of price protection with Eon.

Npower One includes breakdown cover for gas boilers and associated controls and a free emergency helpline. It doesn’t include cover for radiators and other central-heating pipes.