Next come from thermal capacity of the boiler, which should identify the designer, the required parameters of the coolant system, the necessary quality control Boiler heat output depending on outside air temperature (one stage, two stage, stepless infinitely variable), the material from which made the boiler and its weight, size, value and other characteristics and parameters. Choosing the type of fuel for the boiler of his future, it is advisable to consult the district or regional officials. It is necessary to find out what types of fuel applied in the area today, as carried out the order and delivery, as well as find out what's next for the short and long term (eg, gasification district plan, where and what will be built pipelines, the conditions of accession to it of your village, town, etc.). The ideal option is a gas – the most economical fuel. It contains less sulfur compounds, so the burning gas is more efficiency, ie combustion per unit mass of gas is getting more useful heat for heating and hot water, and combustion products containing less polluting substances. Boilers not so subject to corrosion, as the burning of other fuels, less overrun with soot.
Gas boilers easier to clean the soot, and it can be done less frequently. Gas-fired boilers are more durable, do not need to store the fuel for the future, and therefore does not require additional fuel storage area under the house or near it. When using gas as fuel are no odors. (The presence of the smell of gas indicates the poor condition of the boiler.) However, the gas is available not everywhere.