What is the purpose of adjusting the bar in the middle of the floor heating circulating pump?

The horizontal bar in the middle of the floor heating circulating pump is adjusted to release gas during operation. Because the hot water in the floor heating will generate gas under the action of thermal expansion and contraction, the adjustment of the horizontal bar in the middle of the floor heating circulating pump can release gas during the floor heating operation, so as to prevent the air pressure from blocking the floor heating pipeline, causing the water circulation to be unable to pass due to excessive pressure, thus affecting the heating effect of the floor heating.