Air Vent Valve Accessories

How do vent valves work?What are the functions of the exhaust valve and how to replace it?
Air vent valve is a kind of valve accessories.Exhaust valves are used in independent heating systems, central heating systems, heating boilers, central air conditioning, floor heating and solar heating systems and other pipeline exhaust.
The AAV allows air to enter the duct drain system when negative pressure is created in the duct system. When the pressure in the system equalizes, gravity closes the exhaust terminal, preventing sewer gases from escaping into the building.
If your check light is on and you got a po455, po449 or po442, you may need to replace the exhaust valve solenoid.