We always talk to you and give you no-obligation advice on how to choose a boiler which will suits your household’s needs as well as your budget. A combi boiler follows the same heating process as a conventional boiler, but the expansion tank is contained in the boiler itself, so water is heated within the boiler before being sent to the radiators. Before you start looking for insurers, one big fact is utterly vital. No hot water? we can repair or.