A domestic boiler preheater includes a flue box having a combustion gas inlet to receive hot combustion gas from a boiler, and a combustion air inlet to receive air for combustion in a boiler. The preheater further includes a condenser having a mains cold water inlet and a mains water outlet arranged such that mains water flows through the condenser prior to being supplied to a boiler combustion chamber. The condenser further includes a central heating water return and a central heating water flow outlet arranged such that central heating water flows through the condenser prior to being supplied to the boiler combustion chamber. The condenser further includes connections that enable the condenser to be connected to preheated fluid supply pipework from a source of preheated fluid, the preheated fluid having fluid heated by heat from at least one of the combustion gas and a renewable energy source.

The method of construction of a wall heating panel and a wall heating panel consists in constructing an aluminium multi-channel collector, preferably with one phase transition channel, connecting it inseparably with vertical aluminium heating elements, arranging the heating elements in the grooves of a dry wall construction board, preferably magnesium, and filling the space between the grooves and the heating elements with elastic compound, and then applying paperaluminium foil laminate onto the whole surface of the board. A wall heating panel consists of an aluminium collector (1) with stub pipes (2), inside the collector there are horizontal parallel phase transition channels (3) and a water channel (4), the phase transition channel (3) is inseparably connected with the vertical aluminium heating elements (5) which are inserted into the grooves of the dry wall construction board (6), spaces between the grooves and the heating elements are filled with elastic compound (7) and sealed with paperaluminium foil laminate (8), whereas the top part of the collector (1) adjoins the bottom surface of the board (6).

A geothermal heat delivery system is provided for various residential applications, including heating driveways, paths, sidewalks, homes, roofs swimming pools, and commercial applications, including heating roadways, parkways, highways, airport runways, parking lots and sidewalks. A series of heat pipes are used to provide geothermal heat from a borehole to a structure or a surface, which can for example, melt precipitation on a road, driveway or roof.

An evacuated tube boiler comprised of one or more evacuated tubes and a header, operatively connected to form a common internal volume. The internal volume further containing a first heating fluid. A conduit system conducting a second heating fluid through the header and first heating fluid. One or more artificial light sources in proximity to the evacuated tubes. In operation, the artificial light sources radiate light and/or thermal energy to the evacuated tubes whereby the first heating fluid is efficiently heated. The conduit system conducts the second heating fluid through the header and first heating fluid, whereby heat from the first heating fluid is transferred to the second heating fluid. The conduit system conducts the second heating fluid to the point of use. The apparatus may be used in a hydronic boiler heating system for heating a dwelling.