Rational Heat Schemes Using Condensing Boilers in Local Heat Supply Systems

Within the framework of this publication, thermal diagrams of autonomous heat supply systems using condensing heat generators are considered. The insignificant Russian experience of using small condensation boilers in residential construction shows that it is often used to simply replace traditional equipment with condensation technology in existing (or traditionally used) heat schemes, for example, with protection of the boiler from “cold return” by recirculating heat carrier or installing a hydraulic regulator. The consequence of this is almost completely lost the effect of the use of condensing boilers. At the same time, even using the heating temperature schedule of quality regulation 80-60°C and applying water heating to the DHW target up to 45°C you can achieve the effect of the boiler operation in the condensation mode, depending on the construction area, up to 75% of the total working time per year, generating about 70% of thermal energy in the annual cycle. However, it must be borne in mind that the efficiency of the condensing boiler is determined by the part of the latent heat of water vapor in the combustion products, which can be obtained with partial condensation. If this part is small, for example, when cooling the flue gases to 50-45°C (on gas), then the efficiency gain is only 1-3%.