Abstract: An apparatus, based on a heat pipe, is provided for heating a building having at least one enclosed space that is bounded by a wall. The apparatus includes a plurality of passive heat transfer modules distributed along a dimension of the building and a hot source. Each passive heat transfer module includes a closed volume filled with two-phrase heat transfer fluid, at least one evaporator located outside of the enclosed space, downwardly directed heaters formed from a condenser tube, and an adiabatic circuit connecting an outlet of the evaportor and an inlet of the condenser tube. The heaters are spaced from the evaporator and located inside and at a top of the enclosed space to be heated. The hot source is located outside of the enclosed space to be heated but in heat exchange relationship with the evaporator. The hot source includes a lagged duct for the flow of a gas stream at high temperature and the adiabatic circuit passes through the wall of the enclosed space to be heated.

Abstract: A combination water heating and space heating apparatus includes a water heating unit and a space heating unit releasably coupled with the water heating unit. The water heating unit has a water storage tank and a helically wound tubular heat exchanger inside the tank for exhausting products of combustion from a combustion chamber located in a top part of the tank and for transferring heat from the products of combustion to the surrounding water. The space heating unit is an air handler with an hydronic heat exchanger coil and a blower for blowing air over the coil. Hot water is supplied from the tank to the coil and is returned to the tank by means of a water circulation pump located in the space heating unit. Air blown over the coil is heated by the hot water flowing over the coil.