Solar heating

A unit for a ducted, air space heating system powered by an air cooled solar collector, comprising:

• (a) a thermally insulated, airtight housing;
• (b) a plurality of first air ducts leading to and from the solar collector;
• (c) at least one first air outlet from and at least one first air inlet to the housing, which are connectable to and disconnectable from the first air ducts;
• (d) a plurality of second air ducts leading to and from the space to be heated;
• (e) at least one second air inlet to the housing, which are connectable to and disconnectable from the second air ducts;
• (f) a heat store within the housing;
• (g) an air-to-air heat pump in the housing for supplementing the heat provided by the solar collector, the heat pump comprising an evaporator and a condenser, an air-tight partition within the housing separating the heat pump evaporator from the heat pump condenser;
• (h) valve means in the housing, operable to direct air passing through the housing and divide the space heating system into a plurality of air flow paths;
• (i) a plurality of forced draught mechanisms within the housing operable to drive air along the selected air flow paths;
• and
• (j) a control system for controlling the operation of the heat pump, the draight mechanisms and the valve means so as to operate the space heating system to move air along selected air flow paths, wherein the air flow paths include
• a first air flow path in which the heat pump, the forced draught mechanisms, and the valve means are operated such that air flows along the first air flow path, the first air flow path extending from the heat pump evaporator to at least one of the solar collector and the heat store for the air to collect heat and then back to the heat pump evaporator for the air to yield up heat in the heat pump evaporator, and wherein substantially the same mass of air is continuously recirculated along the first air flow path;
• and
• a second air flow path in which the heat pump, the forced draught mechanisms, and the valve means are operated such that air flows along the second air flow path, the second air flow path extending from the heat pump condenser to the space to be heated where the air yields up heat and then back to the heat pump condenser where the air collects further heat.