Solar heating system partially filled with gas to prevent freezing to exposed parts and damage caused by overheating

摘要

The solar heating system is partially filled with gas. With the pump (8) stopped (Fig.1), gas (12) collects at the top of the solar panel (2). Running the pump briefly expels some of the gas (Fig.2) to displace water from the return pipe (4), leaving a reduced volume (13) in the solar panel.