Interface circuit for adding solar heat to a building heating and cooling system

摘要

An interface circuit for adding a solar heat system to a building having a building heating and cooling system and having a building thermostat system, the interface circuit being especially wired to be compatibly interposed between the building thermostat system and the building heating and cooling system without rewiring the latter and being also connected to the solar heat system, the interface circuit thereby adding the solar system as a heat source, and the interface circuit automatically substituting the solar source for the building heating system when heat is called for at a level within the capability of the solar system to supply.