Balance is important in an efficient HVAC system. Take a closer look at balancing dampers on the MCDLG Newsstand.
Control dampers and balancing dampers look the same. They are often listed in the same section on a manufacturer’s website. However, these duct dampers perform distinct functions. Control dampers are a key component in HVAC design, but balancing dampers also have a crucial role.
In this Condenser, we will take a closer look at balancing dampers.
What is a balancing damper?
These dampers work to regulate the static pressure in your duct work. They keep their blades open throughout their operation, but they hold at a specific angle. Balancing dampers are typically locked at a specific angle, but they can be unlocked and readjusted as airflow needs change.
How does it work?
Balancing dampers stay partially open throughout the day. The airstream will lose speed as it passes between the open blades. The damper creates static pressure, which lowers the pressure of the stream as it moves through the damper. This is commonly known as pressure drop.
The amount of pressure drop can change based on the angle of the damper’s blades, generating more static pressure as the blades move closer to fully closed. Technicians will adjust the damper’s blades by hand, measuring the air pressure in the connecting rooms.
Once the pressure is balanced, the technician can lock the blades in place to maintain that balance throughout the day. Some manufacturers will offer balancing dampers with actuators for remote pressure balancing.
Balancing dampers can help achieve pressure balance between connected zones, solving common issues with heating and cooling a space.
Why?
We have several articles on the downside of pressure drop. Pressure drop makes it harder to move air through the system. However, when there are pressure issues in your system, then a loss of pressure can help keep air moving efficiently.
Drafts and cold spots can be tell-tale signs of a pressure issue. It can mean that air isn’t moving all the way through a room, or that the air pressure in one room is greater than in surrounding rooms. A balancing damper at the connecting duct can help alleviate these issues.
What about modulating dampers?
When equipped with a modulating actuator, your control dampers can double as balancing dampers.
Modulating actuators can hold blade angles between fully open and fully closed. Modulating allows the blades to remain partially open when necessary. This means the control dampers can act like a balancing damper. You will still need to test the damper to determine the best blade angle to keep for balanced pressure.
How do you tell the difference?
Check the description of the damper. It's difficult to tell at a glance. Both dampers will look the same in product photos. There may be minor differences in appearance that set them apart.
For example, balancing dampers typically use manual actuators to set the blade angle. Dampers with opposed blades are commonly used for air balancing. Smaller balancing dampers will use a single blade for adjusting air pressure.
The difference comes down to function. Balancing dampers are typically labeled as a “Balance damper” versus a “control damper”.
Check the damper’s submittal for details as well. If you expect pressure issues in your ducts, or you are experiencing cold spots in a room, then consider adding balancing dampers to your ductwork.
For more on airflow dampers, check out these Newsstand articles:
Keep air moving efficiently with the 517-518 series control damper. Arrow United Industries builds the 517 and 518 with airfoil blades and a telescoping drive axle. Designed for efficient airflow and easy installation. Contact Arrow United today and start your next project with the right dampers.