“Simple physics,” Leo grinned. “Cold water pressure is usually 3 or 4 bar. Your gravity-fed hot water tank is only 0.5 bar. The cold water just bulldozes the air bubble back where it came from.”
Leo smiled. “We don’t pull it. We push it.” how to unblock an airlock in water system
“Now for the magic,” he said, and slowly turned on the cold water mains tap. “Simple physics,” Leo grinned