FIELD: heat-engineering. SUBSTANCE: boiler has furnace chamber, vertical gas duct, water tanks of heating system and hot water supply system having adjacent heating surfaces, pressure reducing unit whose inlet is connected to water main and expansion tank which is component of pressure reducing unit. Second pressure reducing unit is located between water main and hot water supply tank. Water tank of heating system is provided with vertical row of tubes inside which combustion products pass; boiler is provided with horizontal row of tubes mounted in staggered order; combustion products flow around these tubes; interior of tubes is communicated with heating system tank. EFFECT: enhanced safety, reliability and efficiency due to intensification of heat exchange process. 2 cl, 1 dwg
