Abstract: A simple solar heating system incorporates a heat dissipater into a heat exchange circuit for bypassing solar collectors when either the temperature or the pressure in the heat exchange circuit exceeds preset limits. In the absence of electric controllers, fluid in the heat exchange circuit is caused to bypass the solar collectors using a valve which is controlled by either the temperature or pressure of the fluid. A solar photovoltaic panel energizes a circulating pump for increasing the rate of pumping as more solar energy is available at the PV panel and decreasing the rate as solar energy decreases.