Hi The safest, most efficient and most economical option is to place a hot water tank, and a radiator heating boiler. The reasons are these: With the hot water tank you will have the hot water service without problems for many years, without maintenance costs, to a dual boiler you have to clean it every year or you will suffer the consequences (there are abundant regrets in the forum). The boiler has an efficiency of 85% versus a single balanced shot heater, which (as the name implies, balances) is at most 50%. And the boiler allows to distribute the heat generated in a single burner to the whole house, that is, with a single source of fire all the environments are heated. Well installed and with minimal maintenance, a central heating system by radiators is by far the best in heating, since it works by convection and not by radiation, does not affect respiratory or circulatory health and values property (it is the formula used by appraisers, a house worth US $ 150,000 if it has central heating is worth US $ 160,000) As for the brand, the one you mentioned is not one of the best boilers (there are also complaints and regrets in the forum and outside of it) I hope it helps you to make a decision, regards!