There are three main types of gas condensing boiler to choose from: a combi, system and conventional. There may come a time when the cost of having an old, faulty or inefficient boiler prompts the question: should i get a new boiler? Combi boilers don’t need hot water cylinders, and therefore require less space in your home. Do you need help now? call () -! Only use piping, sealants and solder suitable for potable water when.