Geothermal energy, solar energy, industrial thermal effluents, etc. mainly offer low-temperature waters. Heating installation or system, originally developed for one of the alternative energy source. The problem of low-temperature heating of greenhouses is not characteristically only for direct application of geothermal energy but is connected to the problem of all the “alternative” energies use for that purpose. Calculations determine the losses of heat transfer, losses from the application of heat and benefit from the use of hot water. Calculated is necessary and permissible temperature of the floor, the recommended speed of the fluid and plan for layout of pipes in the ground of greenhouse.