In order to solve the numerous problems with existing steam, vacuum, and hot water heating systems, first presented is a novel system and method for a vapor vacuum system having low temperature condensate return which can operate without steam traps in both single-pipe and dual-pipe configurations. Secondly is disclosed systems and methods for integrating the disclosed vapor vacuum system with a condensing boiler. Thirdly is presented several systems and method of operating radiators having low temperature condensate return with the disclosed vapor vacuum system. Finally is presented condensing vacuum boiler designs that can be utilized with the disclosed vapor vacuum system. Also presented are embodiments having naturally-induced vacuum and utilizing district heat as well as combined heat and power. All innovations presented herein make vapor vacuum steam more efficient and economical for industrial, commercial, and home applications.