Hvac Dampers And Their Types

A damper is valve that is installed in the ducts or chimney of a HVAC to regulate the flow of air. They are used to cut down the flow of air to unused rooms, to prevent back drafting, stop transmission of noise through the ducts etc. They are of various types. Let’s take a look-

Zone dampers:

A HVAC is designed to circulate air to the whole house. But all parts of the house do not require cool or hot air at the same time throughout the day. In the day time it is the living room where a good airflow is required. And the bed rooms need to be warmed or cooled at night. Thee HVAC is commonly divided up into multiple zones. In most houses, the main floor is considered a single heating zone. The upstairs bedrooms are clubbed as another. This hot or cool air is directed to living room (main zone) in the day time, allowing the unoccupied areas to be at moderate level. This zoning is done through the dampers which open or close to control air flow to rooms. These are generally operated through electricity, vacuum or compressed air. In all the systems a motor is usually connected to the damper through a mechanical coupling.

There are two designs in electric dampers. In the first one the motor is connected at the two stopping points - "damper open" and "damper closed". In other words if the damper is in open position, the motor would run to keep it in this way. It will shut off to close the damper. On the other hand if the damper is in closed position, the motor would run to keep it closed. It will shut to open the damper. The motor is commonly powered from the same 24 volt AC power source that is used for the rest of the control system. This type of damper is connected by low voltage thermostats which require simple wiring. But simultaneous closing and opening all dampers can harm the system.

Another style of electrically powered damper uses a spring-return mechanism and a shaded-pole synchronous motor. Here the force of the spring opens the damper and the force of the motor closes it. Shutting off the electric power re-opens the damper.

In vacuum-operated or pneumatically operated zone dampers, the thermostat switches vacuum on or off. The vacuum in turn moves a spring-loaded rubber diaphragm that regulates the damper.

Back Draft Dampers

These dampers are designed to allow the air to travel in one way. These dampers would prevent the exhaust air to backdraft and get mixed with air inside the living space. They are circular in shape positioned against the walls. They run on gravity which creates natural seal. When air pushes against them from the correct direction, they open up.

Economizer dampers

These dampers are designed to cut down the utility bills generated due to running a HVAC system. When the HVAC is in cooling mode, the economizers bring outside air into a building for cooling purpose. They have two dampers. The outside air damper brings in outside air into the system, while the return air damper takes in the circulated air back into the system.

Face and bypass dampers

These face and bypass dampers work together with a cooling coil to regulate temperature. They can close to make the air take a detour when the temperatures reach the levels that was set. Cutting own airflow will increase the temperature whereas the damper will open to cool the air across the coil.

Duct Vibration Dampeners

The duct carries various types of noises with air that get transmitted into the living space. These noises are very disturbing and can often disrupt sleep at night. Duct vibration dampers are fitted to reduce the level of unwanted noises.



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