Central heating and/or sanitary or industrial hot-water production installation

An installation for central heating and/or hot water production of the type using at least one source of conventional heat of the liquid or gaseous fuel boiler kind, and at least one source of heat pump thermodynamic heat, particularly of the compression heat cycle kind formed by a closed circuit in which flows a refrigerating fluid and comprising in series, in a way known per se, an evaporator, a compressor, a condenser forming the thermodynamic heat source properly speaking, and an expansion member for the condensed refrigerating fluid, one or more circuits for the circulation of the heat-carrying fluid of the central heating and for the production of sanitary or industrial hot water being furthermore provided and arranged to be the seat of heat exchanges with said above-mentioned heat sources, an installation in which a heat pump evaporator is situated in a duct for discharging the combustion gases from the boiler, there being provided in conjunction with this duct, upstream of said evaporator, one or more outside air intakes provided with flow-regulating means, wherein said duct contains several independent evaporators which, considered successively in the flow direction of the gases (air and water vapor and possibly combustion gases) are subjected to decreasing temperatures, each evaporator being associated with a condenser in a compression heat pump heat circuit so that the temperature difference between each evaporator and the condenser which is associated therewith is relatively reduced--of the order of 40.degree. to 45.degree. C.