Is a combi boiler right for you? Sometimes the flue gases get so cool that the water vapour in the gas condenses out, hence the name, and even more energy is recovered from the condensing vapour. We'll do whatever it takes to address your plumbing concerns and leave you satisfied! Electric boiler for c.h basic version power: - kw. to drink orange juice? Does your boiler have a plug? if so, there’s no problem you probably have a two-phase.