The plasticine pair featured in adverts in the Daily Telegraph and the Times over the weekend, which play on the recent widespread snow and plummeting temperatures.
In the advertisements, Gromit is shown standing near a snowman and the strapline reads: "There is only one person who won't appreciate our energy efficient boilers."
According to Npower's marketing director Kevin Peake, the company will use the adverts as longs and the cold weather continues to affect Britain.
The duo were signed up by Npower last month in a deal that will last for two years.
Later this year, Wallace and Gromit will star in television adverts that will urge Npower customers to improve their homes energy efficiency in order to make savings on their monthly gas and electricity bills.
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