We recommend Vaillant and Worcester as these are the two best boilers on the market. Both come with up to 10 year warranties. A good saving can be made by installing a budget boiler. We have been installing Vokera for the last 3 years and they have been very reliable so far. They come with a 7 year warranty.
The type of boiler depends on the system you have. There are four types of gas boiler. Combination boiler, Heat only boiler, System boiler and Stored hot-water boilers. The cheapest option is usually to replace your boiler with the same type of boiler. However you can also change the type of boiler if you so wish. Our free of charge site visit will give us the information we need to advise you on all the options you have.