Searching for ‘best combi boiler for 3 bedroom house'? Well, you've come to the right place. This short guide has everything you need to know to make that all important purchase decision. We'll cover what heat input in kW you need for a typical 3 bedroom house. In addition, we will briefly discuss the best value for money boilers currently on the market. When choosing the best boiler. There are lots of things to consider when choosing an installer to fit a brand new boiler. I hope to guide you through the process from start to finish.