A heating system for hot water and conditioned air uses electromagnetic energy created by one or more magnetrons operated by high voltage transformers. The heating system includes oil cooled transformers and magnetrons. Using radiators in the form of heat exchangers, heat recovered from the transformers and magnetrons is dissipated directly into the path of the return air and the air handler blower. The magnetron heating system includes a coiled conduit sized to allow complete heating of the fluid flowing therethrough. The conduit has a conical shape to allow upper magnetrons to heat the outside of the conduit and lower magnetrons to heat the inside of the conduit.