Float Type Air vent valve is a kind of valve to vent troublesome air from hydronic heating systems. It is commonly used for air release in plumbing heating system and installed at the highest point of the system and is often seen on radiators, manifold and water separators.

A float type automatic air vent valve includes a brass body, safety cover, a polypropylene float,  spring loaded lever, spring, and EPDM o-rings.

How Does A Air Vent Valve Work?

During normal operation, the pipeline will naturally produce a small amount of gas, which will gather in the upper part of the pipe. To a certain extent, the water level in the valve will drop, and the float will drop along the water. The air will be discharged from the small hole.

When the air is overflow in the system, the air will climb up along the pipeline and finally gather at the highest point of the system, while the air vent valve is also generally installed at the highest point of the system. When the air enters into the air vent valve chamber and gathers at the upper part of vent valve, the pressure rises. When the air pressure exceeds the system pressure, the air will make the water drop in the chamber, and the float will also fall with the water level and open the vent port. When the air is released at all, the water lever enter and the float will rise, the vent opening port will be closed.

In case of power failure or pump shutdown, the negative pressure will occur when the water in the pipeline is empty. The float will drop along with the water. In this case, it is necessary to open the small hole to drive the large hole to make more air enter to ensure the safety of the pipeline.

Attention

If the cap on the valve’s top body is tightened, the valve will stop venting. Generally, the top cap should be open. The air vent valve can also be used together with the check valve to facilitate the maintenance.